Antennas with reduced space and improved performance

Description of equivalent WO 2004057698 A2

ANTENNAS WITH REDUCED SPACE AND IMPROVED

PERFORMANCE

FIELD OF THE INVENTION

[0001] The present invention relates generally to the field of wireless communications, and particularly to the size reduction and performance improvement of capacitively loaded magnetic dipole antennas.

BACKGROUND OF THE INVENTION [0002] An antenna is an electrical conductor or array of conductors that radiates (transmits and/or receives) electromagnetic waves. A magnetic dipole antenna is a loop antenna that radiates electromagnetic waves in response to current circulating through the loop. Electromagnetic waves are often referred to as radio waves. Most antennas are resonant devices, which operate efficiently over a relatively narrow frequency band. An antenna must be tuned to the same frequency band that the system using it operates in, otherwise reception and/or transmission will be impaired.

[0003] The bandwidth of an antenna refers to the range of frequencies over which the antenna can operate satisfactorily. It is usually defined by impedance mismatch but it can also be defined by pattern features such as gain, beamwidth, etc.. Antenna designers quickly assess the feasibility of an antenna requirement by expressing the required bandwidth as a percentage of the center frequency of the band. Different types of antennas have different bandwidth limitations. Normally, a fairly large volume is required if a large bandwidth is desired. Accordingly, the present invention addresses the needs of small compact antenna with wide bandwidth. The present invention provides a versatile antenna design that resonates at more than one frequency, that is it is multiresonant, and that may be adapted to a variety of packaging configurations. [0004] The antenna contains one or more elements. Elements are the conductive parts of an antenna system that determine the antenna's electromagnetic characteristics. The element of an magnetic dipole antenna is designed so that it resonates at a predetermined frequency as required by the application for which it is being used. The antenna's resonant frequency is dependant on the capactive and inductive properties of the antenna elements. The capacitive and inductive properties of the antenna elements are dictated by the dimensions of the antenna elements and their interrelations.

[0005] The radiated electromagnetic wave from an antenna is characterized by the complex vector E x H in which E is the electric field and H is the magnetic field. Polarization describes the orientation of the radiated wave's electric field. For maximum performance, polarization must be matched to the orientation of the radiated field to receive the maximum field intensity of the electromagnetic wave. If it is not oriented properly, a portion of the signal is lost, known as polarization loss.

[0006] Dependent on the antenna type, it is possible to radiate linear, elliptical, and circular signals. In linear polarization the electric field vector lies on a straight line that is either vertical (vertical polarization), horizontal (horizontal polarization) or on a 45 degree angle (slant polarization). If the radiating elements are dipoles, the polarization simply refers to how the elements are oriented or positioned. If the radiating elements are vertical, then the antenna has vertical polarization and if horizontal, it has horizontal polarization. In circular polarization two orthogonal linearly polarized waves of equal amplitude and 90 degrees out of phase are radiated simultaneously.

[0007] Magnetic dipole antennas can be designed with more than one antenna element. It is often desirable for an antenna to resonate at more than one frequency. For each desired frequency, an antenna element will be required. Different successive resonances occur at the frequencies fi, f₂, fj... f_n. These peaks correspond to the different electromagnetic modes excited inside the structure. The antenna can be designed so that the frequencies provide the antenna with a wide bandwidth of coverage by utilizing overlapping or nearly overlapping frequencies. However, antennas that have an wider bandwidth than a monoresonant antenna often have a correspondingly increased size.

[0008] Small antennas are desired for use in and with portable wireless communication devices. With classical antenna structures, a certain physical volume is required to produce a resonant antenna structure at a particular radio frequency and with a particular bandwidth. Thus, traditionally bandwidth and frequency requirements dictated the volume of an antenna, and therefore to some extent placed limitations upon the design of wireless devices. Many present day applications require that antennas provide large bandwidth, efficiency, and isolation in as small form factor as possible.

[0009] Thus, there is a need in the art for a multiresonant antenna; wherein the individual antenna elements share volume within the antenna structure.

SUMMARY OF THE INVENTION [0010] The present invention includes antenna elements and antenna element arrangements having a generally low profile, improved isolation, and a large bandwidth in comparison to prior art antennas. In one aspect of the present invention, the antenna elements include both capacitive and inductive parts. Each element provides a frequency or band of frequencies to the antenna. The preferred embodiments relate to a capacitively loaded magnetic dipole

(CLMD) antenna having antenna elements having improved grounding characteristics to improve isolation. Other embodiments provide a reduction in the footprint of the antenna elements while maintaining the perfonnance characteristics by providing a greater surface area on either a top, middle or bottom portion of a CLMD antenna. [0011] Further embodiments provide antenna element arrangements with improved radiation efficiency by providing metallic reflectors on the sides of antenna elements. In still other embodiments, the isolation characteristics of antenna elements are improved through the use of coplanar wave guides. The bandwidth may be improved through the use of stubs resonators. In yet further embodiments, the bandwidth of the antenna elements is improved without reducing isolation or shielding by providing a variable gap between two portions of the antenna elements.

[0012] In other embodiments, shielding of the antenna element is improved by providing a shield between at least a portion of the antenna element and a ground plane. In additional embodiments, a lower profile is achieved by positioning the antenna elements in a coplanar manner with a ground plane. In further embodiments, the isolation of the antenna element is improved by positioning the antenna element in a cutout provided in the ground plane. In still further embodiments, the antenna element arrangement may achieve a larger bandwidth by positioning two or more antenna elements in a plurality of cutouts in the ground plane. Further, a savings in volume may be achieved by positioning other components within the footprint of the antenna element.

[0013] The present invention includes a wireless device comprising: a first portion; a second portion, the first and second portion disposed to effectuate a capacitive area; and a third portion, the third portion coupled to the first portion and to the second portion to effectuate an inductive area, wherein the third portion comprises a length having a first end and a second end, wherein the length is longer than a straight line distance between the first end and the second end, and wherein the first portion, the second portion, and the third portion define a capacitively coupled dipole antenna.

[0014] The present invention includes a dipole antenna comprising: a first portion; a second portion, the first and second portion disposed to create a capacitive area; and a third portion, the third portion comprising one or more portion, the third portion coupled to the first portion and to the second portion to create an inductive area, wherein the third portion comprises a length having a first end and a second end, and wherein the length is longer than a straight line distance between the first end and the second end. One or more portion of the third portion may be disposed relative to the first portion and the second portion in a non- parallel relationship. One or more portion of the third portion may be disposed relative to the first portion and the second portion in a parallel relationship. The first and second portion may be disposed in a generally coplanar relationship, and one or more portion of the third portion may be disposed in a plane that is in an angular relationship relative to the coplanar relationship of the first and second portion. The first portion, the second portion, and the third portion may be disposed on or above a ground plane. The antenna may include a substrate, wherein the first portion and the second portion are coupled to the substrate. The antenna may include a FR4 substrate. The FR4 substrate may be defined by a periphery, wherein within the periphery the FR4 substrate defines a void, and wherein the capacitive area generally spans the void. The first portion, the second portion, and the third portion may be coupled to crate a capacitively coupled dipole antenna.

[0015] The present invention includes a system, comprising: a dipole antenna including, a first portion; a second portion, the first and second portion disposed in a relationship to create a capacitive area; and a third portion, the third portion coupled to the first portion and to the second portion and disposed to create an inductive area, wherein the third portion comprises a length having a first end and a second end, and wherein the length is longer than a straight line distance between the first end and the second end. The antenna may further include a high dissipation factor substrate. The antenna may include an FR4 substrate. The first and second portion may be coupled to the FR4 substrate, wherein the FR4 substrate is defined by a periphery, wherein within the periphery the FR4 substrate defines a void, and wherein the capacitive area generally spans the void. The system may comprise a wireless communications device.

[0016] The present invention includes a capacitively couple dipole antenna, comprising: capacitance means for creating a capacitance; and inductive means for creating an inductance. The antenna may comprise a first portion, a second portion, and a third portion, wherein the third portion comprises a length having a first end and a second end, and wherein the length is longer than a straight line distance between the first end and the second end. The antenna may comprise a substrate. The first and second portion may be coupled to the substrate, wherein the substrate is defined by a periphery, wherein within the periphery the substrate defines a void, wherein the capacitance generally spans the void.

[0017] The present invention includes a method for creating a resonance in a resonant circuit comprising the steps of: providing a first portion; providing a second portion; disposing the first and second portion to crate a capacitive area; and providing a third portion, wherein the third portion comprises a length having a first end and a second end, and wherein the length is longer than a straight line distance between the first end and the second end; and coupling the third portion to the first portion and to the second portion to create an inductive area. The method may further include the step of: providing a high dissipation factor substrate, wherein the high dissipation factor substrate is defined by a periphery, wherein within the periphery the high dissipation factor substrate defines a void, and wherein the capacitive area generally spans the void.

[0018] In a preferred embodiment, the basic antenna element comprises a substantially planar structure with a planar conductor and a pair of parallel elongated conductors, each having a first end electrically connected to the planar conductor. Additional elements may be coupled to the basic element in an array. In this way, individual antenna structures share common elements and volumes, thereby increasing the ratio of relative bandwidth to volume. [0019] Other embodiments and other features will become apparent by referring to the Description and the Claims that follow. This summary does not purport to define the invention. The invention is defined by the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 conceptually illustrates the antenna designs of the present invention.

[0021] Figure 2 illustrates the increased overall bandwidth achieved with a multiresonant antenna design.

[0022] Figure 3 is an equivalent circuit for a radiating structure.

[0023] Figure 4 is an equivalent circuit for a multiresonant antenna structure.

[0024] Figure 5 A illustrates a three-dimensional view of an embodiment of an antenna element;

[0025] Figure 5B illustrates a side-view of the antenna element illustrated in Figure 5 A;

[0026] Figure 6A illustrates a side-view of an embodiment of antenna element in accordance with the present invention;

[0027] Figure 6B illustrates a side-view of another embodiment of antenna element in accordance with the present invention;

[0028] Figure 6C illustrates a side-view of yet another embodiment of antenna element in accordance with the present invention;

[0029] Figure 7A illustrates a side-view of another embodiment of an antenna element in accordance with the present invention;

[0030] Figure 7B illustrates a side-view of various embodiments of the bottom portion of the antenna element illustrated in Figure 3 A;

[0031] Figure 7C illustrates a side-view of another embodiment of an antenna element in accordance with the present invention;

[0032] Figure 7D illustrates a side-view of various embodiments of the bottom portion of the antenna element illustrated in Figure 3C; [0033] Figure 7E illusfrates a side-view of another embodiment of an antenna element in accordance with the present invention;

[0034] Figure 7F illustrates a side-view of various embodiments of the bottom portion of the antenna element illustrated in Figure 3E;

[0035] Figure 8A illustrates a three-dimensional view of an embodiment of an antenna element arrangement in accordance with the present invention;

[0036] Figure 8B illustrates a side-view of the antenna element arrangement illustrated in Figure 4A;

[0037] Figure 8C illustrates a top-view of the antenna element arrangement illustrated in Figures 4A and 4B;

[0038] Figure 9A illustrates a top-view of an embodiment of an antenna element arrangement in accordance with the present invention;

[0039] Figure 9B illustrates a radio frequency (RF) schematic of the antenna element arrangement of Figure 5 A;

[0040] Figure 9C illustrates a top-view of another embodiment of an antenna element arrangement in accordance with the present invention;

[0041] Figure 9D illustrates a radio frequency (RF) schematic of the antenna element arrangement of Figure 5C;

[0042] Figure 9E illustrates a top-view of another embodiment of an antenna element arrangement in accordance with the present invention;

[0043] Figure 9F illustrates an embodiment of a radio frequency (RF) schematic of the antenna element arrangement of Figure 5E;

[0044] Figure 9G illustrates another embodiment of a radio frequency (RF) schematic of the antenna element arrangement of Figure 5E;

[0045] Figure 9H illustrates yet another embodiment of a radio frequency (RF) schematic of the antenna element arrangement of Figure 5E;

[0046] Figure 10A illustrates a side-view of an embodiment of an antenna element;

[0047] Figures 10B and 6C illustrate cross-sectional views taken along VLB- VLB of the antenna element illustrated in Figure 10 A; [0048] Figure 10D illustrates a side-view of an embodiment of an antenna element in accordance with the present invention;

[0049] Figure 11 A illustrates a side-view of another embodiment of an antenna element in accordance with the present invention;

[0050] Figure 1 IB illustrates a side-view of still another embodiment of an antenna element in accordance with the present invention;

[0051] Figure 1 IC illustrates a side-view of yet another embodiment of an antenna element in accordance with the present invention;

[0052] Figure 12A illustrates a side-view of an embodiment of an antenna element in accordance with the present invention;

[0053] Figure 12B illustrates a side-view of another embodiment of an antenna element in accordance with the present invention;

[0054] Figure 12C illusfrates a side-view of yet another embodiment of an antenna element in accordance with the present invention;

[0055] Figure 12D illustrates a side-view of still another embodiment of an antenna element in accordance with the present invention;

[0056] Figure 13 A illustrates a side-view of an embodiment of an antenna element arrangement in accordance with the present invention;

[0057] Figure 13B illustrates a side-view of another embodiment of an antenna element arrangement in accordance with the present invention;

[0058] Figure 13C illustrates a side-view of still another embodiment of an antenna element arrangement in accordance with the present invention;

[0059] Figure 13D illusfrates a side-view of yet another embodiment of an antenna element arrangement in accordance with the present invention;

[0060] Figure 14 illustrates a three-dimensional view of an embodiment of an antenna element arrangement in accordance with the present invention;

[0061] Figure 15 A illustrates a top view of an embodiment of an antenna element arrangement in accordance with the present invention; [0062] Figure 15B illustrates a top view of another embodiment of an antenna element arrangement in accordance with the present invention;

[0063] Figure 16A illustrates a top view of an embodiment of an antenna element arrangement in accordance with the present invention;

[0064] Figure 16B illustrates a top view of another embodiment of an antenna element arrangement in accordance with the present invention; and

[0065] Figure 17 illustrates a top view of still another embodiment of an antenna element arrangement in accordance with the present invention.

[0066] Figures 18 A-B illustrate a respective three-dimensional and side view of a capacitively loaded dipole antenna.

[0067] Figure 18C illustrates a three dimensional view of a low profile/small form factor capacitively loaded dipole antenna.

[0068] Figure 19 illustrates a three dimensional view of a low profile/small form factor capacitively loaded dipole antenna.

[0069] Figures 20A-B illustrate three dimensional views of a low profile/small fomi factor capacitively loaded dipole antenna.

[0070] Figure 21 illustrates a low profile/small form factor antenna in accordance with the principles of the present invention.

[0071] Figure 22 illusfrates two low profile/small form factor antennas in accordance with the principles of the present invention coupled together.

[0072] Figure 23 illustrates a basic radiating structure utilized in an embodiment of the present invention.

[0073] Figure 24 illustrates a dual-mode antenna in accordance with an embodiment of the present invention.

[0074] Figure 25 illusfrates a multimode antenna in accordance with another embodiment of the present invention.

[0075] Figure 26 illusfrates an antenna in accordance with the present invention that is formed flat on a substrate. [0076] Figure 27 illusfrates an antenna in accordance with an embodiment of the present invention with returns for ground and a feed.

[0077] Figures 28A-C illustrate the use of vias to provide feeds and shorts for an antenna in accordance with an embodiment of the present invention.

[0078] Figures 29A-C illustrate a dual frequency antenna in accordance with an embodiment of the present invention with side-by-side elements.

[0079] Figure 30 illusfrates a dual frequency antenna in accordance with an embodiment of the present invention with nested elements.

[0080] Figure 31 illustrates an antenna in accordance with an embodiment of the present invention similar to that of Fig. 30 with an additional capacitive element to provide an additional resonant frequency.

[0081] Figures 32A-B illustrate a two-sided antenna in accordance with an embodiment of the present invention with three frequencies on one face of a substrate and a single frequency on the other face.

[0082] Figures 33 A-B illustrate an antenna in accordance with an embodiment of the present invention with conductors formed on the edge as well as the face of a subsfrate.

[0083] Figures 34A-B illustrate a multifrequency planar antenna in accordance with an embodiment of the present invention on a primary substrate with an additional radiating element on a perpendicular secondary substrate.

[0084] Figures 35 A-B illusfrate antennas in accordance with an embodiment of the present invention with multiple secondary substrates.

[0085] Figure 36 illustrates an antenna in accordance with an embodiment of the present invention with an extended radiating element.

[0086] Figure 37 illustrates an antenna in accordance with an embodiment of the present invention with a pair of extended radiating elements.

[0087] Figure 38 shows the antenna of Fig. 37 within an enclosure in accordance with an embodiment of the present invention.

[0088] Figure 39 illusfrates an antenna similar to that of Fig. 37 with additional radiating elements on peφendicular secondary substrates in accordance with an embodiment of the present invention. [0089] Figure 40 shows the antenna of Fig. 39 within an enclosure in accordance with an embodiment of the present invention.

[0090] Figure 41 illusfrates an antenna structure in accordance with an embodiment of the present invention with two radiating elements at opposite ends of a substrate.

[0091] Figure 42 illusfrates a laptop computer in accordance with an embodiment of the present invention with multiple radiating elements.

[0092] Figure 43 illustrates an antenna in accordance with an embodiment of the present invention printed on a subsfrate with a milled groove between the conductors.

[0093] Figure 44 illustrates a multifrequency antenna in accordance with an embodiment of the present invention with a plurality of milled grooves.

[0094] Figure 45 illustrates an alternative method of fabricating an antenna structure in accordance with an embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [0095] The disclosed embodiments of the present invention include antenna elements and antenna element arrangements having a generally low profile, improved isolation, and providing a larger bandwidth.

[0096] The volume to bandwidth ratio is one of the most important constraints in modern antenna design. The physical volume of an antenna can place severe constraints on the design of small electronic devices. One approach to increasing this ratio is to re-use the volume for different modes. Some designs already use this approach, even though the designs do not optimize the volume to bandwidth ratio. In these designs, two modes are generated using the same physical structure, although the modes do not use exactly the same volume. The current repartition of the two modes is different, but both modes nevertheless use a common portion of the total available volume of the antenna. This concept of utilizing the physical volume of the antenna for a plurality of antemia modes is illustrated generally by the Venn Diagram of Figure 1. The physical volume of the antenna ("V") has two radiating modes. The physical volume associated with the first mode is designated 'Vi', whereas that associated with the second mode is designated 'V₂'. It can be seen that a portion of the physical volume, designated 'Vι,₂', is common to both of the modes.

[0097] The concept of volume reuse and its frequency dependence are expressed with reference to "K law". The general K law is defined by the following:

Af / f = K * V / λ³ [0098] wherein Δf/f is the normalized frequency bandwidth, λ is the wavelength, and the term V represents the physical volume that will enclose the antenna. This volume so far has not been optimized and no discussion has been made on the real definition of this volume and the relation to the K factor. [0099] In order to have a better understanding of the K law, different K factors are defined:

K_mod_ai is defined by the mode volume Vi and the corresponding mode bandwidth:

Af, I t = K_{moά al} . V, I λ* where i is the mode index.

K_mod i is thus a constant related to the volume occupied by one electromagnetic mode. _effecti_ve is defined by the union of the mode volumes <img file="WO2004057698A2_D0001.tif" /> U V₂U.N; and the cumulative bandwidth.

It can be thought of as a cumulative K:

Σ_i Af, l f_i = K_effective . {Vx V₂ ..V,)l λ where λ is the wavelength of the central frequency.

[0100] Keffe_cti_ve is a constant related to the minimum volume occupied by the different excited modes taking into account the fact that the modes share a part of the volume. The different frequencies fj must be very close in order to have nearly overlapping bandwidths.

[0101] Kph sicai or Ko served is defined by the physical volume 'V of the antenna and the overall antenna bandwidth:

Af/ f = K_physlcal . V/ λ³ [0102] Kphysi_cai or K_observed i he most important K factor since it takes into account the real physical parameters and the usable bandwidth. K_Phy_Sicai is also referred to as K_o served since it is the only K factor that can be calculated experimentally. In order to have the modes confined within the physical volume of the antenna, K_phy_Sic_ai must be lower than Keff_ective- However these K factors are often nearly equal. The best and ideal case is obtained when

Kph sicai i approximately equal to Keffective and is also approximately equal to the smallest K_modai- It should be noted that confining the modes inside the antemia is important in order to have a well-isolated antenna.

[0103] One of the conclusions from the above calculations is that it is important to have the modes share as much volume as possible in order to have the different modes enclosed in the smallest volume possible. As previously discussed, the concept is illustrated in the Venn Diagram shown in Figure 1. Maximizing the number of modes while minimizing the volume of the antenna results in antennas that are multiresonant, yet are not much larger than a monoresonant antenna.

[0104] For a plurality of radiating modes i, Figure 2 shows the observed return loss of a multiresonant structure. Different successive resonances occur at the frequencies f_ls f₂, fj... f_n. These peaks correspond to the different electromagnetic modes excited inside the structure. Figure 2 illustrates the relationship between the physical, or observed, K and the bandwidth over f_\ to f_n.

[0105] For a particular radiating mode with a resonant frequency at f_la we can consider the equivalent simplified circuit LiCi shown in Figure 3. By neglecting the resistance in the equivalent circuit, the bandwidth of the antenna is simply a function of the radiation resistance. The circuit of Figure 3 can be repeated to produce an equivalent circuit for a plurality of resonant frequencies. [0106] Figure 4 illustrates a multimode antenna represented by a plurality of inductance(L)/capacitance(C) circuits. At the frequency fi only the circuit LiCi is resonating. Physically, one part of the antenna structure resonates at each frequency within the covered spectrum. By utilizing antenna elements with overlapping resonance frequencies of fi to f_n, an antenna in accordance with the present invention can cover frequencies 1 to n. Again, neglecting real resistance of the structure, the bandwidth of each mode is a function of the radiation resistance.

[0107] As discussed above, in order to optimize the K factor, the antenna volume is reused for the different resonant modes. One embodiment of the present invention utilizes a capacitively loaded microsfrip type of antenna as the basic radiating structure. Modifications of this basic structure will be subsequently described. In a highly preferred embodiment, the elements of the multimode antenna structures have closely spaced resonance frequencies.

[0108] Figures 5A and 5B illustrate an embodiment of a capacitively loaded magnetic dipole (CLMD) antenna in accordance with the principles of the present invention. The antenna element 10 includes a top portion 12, a middle portion 14 and a bottom portion 16. Each portion 12, 14, 16 may be a two-dimensional plate or a one-dimensional element. The top portion 12 and the middle portion 14 form a capacitive component 18 of the antenna element 10. A loop between the middle portion 14 and the bottom portion 16 forms an inductive component 20 of the antenna element 10. The antenna element 10 is connected to a grounding plane 22 by a grounding point 24. A feeding line 26 provides power to the antenna element 10.

[0109] Figure 6A illustrates a side-view of an antenna element 28 similar to the antenna element 10 described above with reference to Figures 5 A and 5B. The antenna element 28 includes a top portion 30, middle portion 32 and bottom portion 34 forming a capacitive component and an inductive component. The embodiment illustrated in Figure 6A provides improved grounding of the antenna element 10 to a grounding plane (not shown in Figure 6A) through an elongated grounding point 36. The elongated grounding point 36 illusfrated in Figure 6 A extends from one end of the bottom portion 34 inward by a predetermined length. The size of the grounding point 36 may be selected for the desired grounding characteristics of the antenna element 28. Thus, the embodiment illustrated in Figure 6A provides a larger surface area for the grounding of the antenna element 28.

[0110] Figure 6B illustrates another embodiment of an antenna element with improved grounding characteristics, h this embodiment, an antenna element 38 has a top portion 40, a middle portion 42 and a bottom portion 44. The antenna element 38 is provided with a plurality of grounding points 46 extending downward from the bottom portion 44 for improved grounding of the antenna element 38. In the embodiment illusfrated in Figure 6B, four grounding points 46 are provided. The four grounding points 46 are positioned in an equally spaced apart configuration on one side of the bottom portion 44.

[0111] Figure 6C illustrates yet another embodiment of an antenna element with improved grounding characteristics. In this embodiment, an antenna element 48 has a top portion 50, a middle portion 52 and a bottom portion 54. The antenna element 48 is provided with a pair of grounding points 56 extending downward from the bottom portion 44. The two grounding points 46 are positioned at one end and the middle of the bottom portion 44 for improved grounding of the antenna element 48.

[0112] Figure 7A illusfrates a side-view of a CLMD antenna element adapted to provide improved performance while maintaining a relatively small package size or footprint. The illusfrated antenna element 58 includes a top portion 60, a middle portion 62 and a bottom portion 64. While the top portion 60 and the middle portion 62 are similar to those illustrated in the above-described embodiments, the embodiment illustrated in Figure 7A includes a bottom portion 64 having a V-shaped ridge pattern. The ridged pattern of the bottom portion 64 effectively provides a greater surface area for the bottom portion 64 without increasing the footprint of the antenna element 58. In certain embodiments, the bottom of one or more ridge may serve as a grounding point. In other embodiments, as illusfrated in Figure 7A, a separate grounding point may be provided. Thus, improved performance is achieved without increasing the size of the antenna element.

[0113] Figure 7B illustrates a variety of ridged patterns which may be applied to the bottom portion 64 of the antenna element 58 illustrated in Figure 7 A. As illustrated in Figure 7B, the size and shape of the ridges may be varied to achieve desired performance characteristics of the antenna element.

[0114] Figure 7C illusfrates another embodiment of an CLMD antenna element with improved performance without increasing or modifying the footprint. The antenna element 66 illusfrated in Figure 7C includes a top portion 68 and a middle portion 70 similar to those described above. The antenna element 66 includes a bottom portion 72 having block ridges formed thereon. As illustrated in Figure 7D, the block ridges may be formed of a variety of shapes and sizes to provide the desired performance characteristics for the antenna element 66.

[0115] Figure 7E illusfrates yet another embodiment of an CLMD antenna element with improved performance without improved footprint. The antenna element 74 illusfrated in Figure 3E includes a top portion 76 and a middle portion 78 similar to those described above. The antenna element 74 includes a bottom portion 80 having saw-tooth ridges formed thereon. As illusfrated in Figure 3F, the saw-tooth ridges may be formed of a variety of shapes and sizes to provide the desired performance characteristics for the antenna element 66. [0116] Figure 8A-8C illustrate an antenna element arrangement for providing a different field distribution and increased grounding of the antenna element. The antenna element arrangement 82 includes an antenna element 84 grounded on a grounding plane 86 by a pair of grounding points 88, 90. The antenna element 84 is positioned substantially perpendicular to the plane of the grounding plane 86. A metallic reflector 92, 94 is provided on each side of the antenna element 84. The reflectors 92, 94 are positioned substantially perpendicular to the plane of the grounding plane 86 and substantially perpendicular to the plane of the antenna element 84. Thus, the metallic reflectors 92, 94 serve to improve the radiation efficiency of the antenna element 84 by altering the field distribution.

[0117] Figure 9A illustrates an embodiment of an antenna element arrangement in accordance with the present invention. The antenna element arrangement 96 includes an antenna element 98 positioned atop a ground plane 100 and grounded through a ground pad 102. A coplanar wave guide (CPWG) 104 is provided on the board of the communication system to feed the antenna element 98. CPWG's are well known to those skilled in the art. The CPWG 104 provides the antenna element 98 with improved isolation characteristics. Figure 9B illustrates a radio frequency (RF) schematic corresponding to the embodiment illusfrated in Figure 9 A. As noted above, the CPWG 104 is in communication with the antenna element 98.

[0118] Figure 9C illustrates another embodiment of an antenna element arrangement in accordance with the present invention. The arrangement 106 includes an antenna element 108 positioned atop a ground plane 110 and grounded through a ground pad 112. A CPWG 114 is provided in communication with the antenna element 108. Further, the arrangement 106 includes a single-stub resonator 116. The position, line, and width of the stub 116 on the line (CPWG) are dependent upon the input impedance of the antenna. Stubs are well known to those skilled in the art and can be either open-circuited or short-circuited. The arrangement 106 may include any number of stubs 116. The number of studs may be selected depending on the bandwidth requirements of the antenna element 108. Stubs are low-Q systems, collecting energy at the frequency near that of the antenna. This energy is then leaked from the stub and radiated by the antenna, thus improving the bandwidth of the antenna. Figure 9D illustrates an RF schematic of the embodiment illusfrated in Figure 9C.

[0119] Figure 9E illustrates yet another embodiment of an antenna element arrangement in accordance with the present invention. The arrangement 118 includes an antenna element 120 positioned atop a ground plane 122 and grounded through a ground pad 124. A CPWG 126 is provided in communication with the antenna element 120. Further, the arrangement 118 includes two stubs 128a, 128b. The two stubs 128a, 128b create two different resonant frequencies, which may be used to improve the bandwidth of the antenna element 120. Again, the position, line, and width of the stub on the line (CPW) are dependent upon the input impedance of the antenna. Figures 9F-9H illusfrate various embodiments of radio frequency (RF) schematics of the antenna element arrangement described above with reference to Figure 9E.

[0120] Figure 10A illusfrates an antenna element similar to that described above with reference to Figures 5A and 5B. The antenna element 130 includes a top portion 132 and a middle portion 134 that are separated by a gap of size d. An electric field 136 is formed in the gap between the top portion 132 and the middle portion 134 when the antenna element is charged. The size of the gap, d, affects the confinement of the electric field 136 and, thus, the isolation and bandwidth of the antenna element 130. A smaller gap size, d, results in a more confined electric field, providing increased isolation and shielding for the antenna element 130. Conversely, a larger gap size, d, results in a less confined electric field 136, providing reduced isolation and shielding, but a larger bandwidth. [0121] Figures 10B and IOC are cross-sectional views along VLB-VLB of Figure 10A and illustrate the shape of the electric field 136 with variations is the size of the gap. Figure 10B illustrates an electric field for a relatively small gap size, while Figure IOC illustrates the electric field for a relatively large gap size.

[0122] Figure 10D illustrates an embodiment of an antenna element adapted to provide greater bandwidth without reducing shielding. The illustrated antenna element 138 includes a top portion 140, a middle portion 142 and a bottom portion 144. hi this embodiment, the middle portion 142 is angled downward as it protrudes inward. This angled configuration results in a tapered gap 146 between the top portion 140 and the middle portion 142. The tapered gap 146 provides the antenna element 138 with greater bandwidth capability without sacrificing shielding.

[0123] Figures 11A-1 IC illustrate additional embodiments of antenna elements having variable gaps between the top portions and the middle portions. Figure 11 A illustrates an antenna element 148 having a top portion 150 and a middle portion 152. The middle portion 152 is provided with a downwardly stepped configuration to provide a gap 154 with a variable size between the top portion 150 and the middle portion 152. Although the embodiment illustrated in Figure 11 A is provided with a middle portion 152 having three steps, other embodiments may have any practical number of steps.

[0124] Figure 1 IB illusfrates an antenna element 156 having a top portion 158 and a middle portion 160. The middle portion 160 is upwardly angled to provide a tapered gap 162 with a variable size between the top portion 158 and the middle portion 160.

[0125] Figure 1 IC illustrates an antenna element 166 having a top portion 168 and a middle portion 170. The middle portion 170 is provided with a upwardly stepped configuration to provide a gap 172 with a variable size between the top portion 168 and the middle portion 170.

[0126] Figures 12A-12D illusfrate further embodiments of antenna elements in accordance with the present invention. The illustrated embodiments provide antenna elements with reduced sizes (or footprints) without a decrease in performance.

[0127] Figure 12A illusfrates an antenna element 174 with a top portion 176, a middle portion 178 and a bottom portion 180. In this embodiment, a larger surface area for the middle portion 178 is achieved through a ridged configuration. In the illustrated embodiment, the middle portion 178 is provided with a plurality of block ridges to maintain the electric field sfrength between the top portion 176 and the middle portion 178 while reducing the footprint of the antenna element 174. Other embodiments may include slanted ridges 179 or rounded ridges 181, as illustrated in Figure 12A.

[0128] Figure 12B illustrates an antenna element 182 with a top portion 184, a middle portion 186 and a bottom portion 188. In this embodiment, a larger surface area for the top portion 184 is achieved through a ridged configuration. In the illustrated embodiment, the top portion 184 is provided with a plurality of block ridges to maintain the electric field strength between the top portion 184 and the middle portion 186 while reducing the footprint of the antenna element 182.

[0129] Figure 12C illustrates an antenna element 190 with a top portion 192, a middle portion 194 and a bottom portion 196. Ln this embodiment, both the top portion 192 and the middle portion 194 are provided with a ridged configuration, resulting a larger surface area for each. As with the embodiments described above with reference to Figures 12A and 12B, the ridged configurations allow the antenna element 190 to maintain the elecfric field strength between the top portion 192 and the middle portion 194 while reducing the footprint of the antenna element 182. Configuring both the top portion 192 and the middle portion 194 with ridges allows for an increased reduction in the footprint.

[0130] Figure 12D illustrates an antenna element 198 with a top portion 200, a middle portion 202 and a bottom portion 204. In this embodiment, both the top portion 192 and the middle portion 194 are provided with parallel ridges. Thus, the top portion 200 and the middle portion 202 frack each other, maintaining a constant gap size between them. As with the embodiments described above with reference to Figures 12A-12C, the ridged configurations allow the antenna element 198 to maintain the electric field strength between the top portion 200 and the middle portion 202 while reducing the footprint of the antenna element 198.

[0131] The features of the embodiments of the antenna elements described above with reference to Figures 12A-12D effectively change the inductance or the capacitance of the CLMD antenna element. It will be understood by those skilled in the art that the various features may be combined to change both the inductance and capacitance in order to achieve desired antenna element characteristics.

[0132] Figures 13A-13D illustrate further embodiments of antenna elements in accordance with the present invention. The illustrated embodiments provide improved isolation by at least partially shielding the bottom plate of the antenna elements from a grounding plane and modifying the inductance component of the antenna elements.

[0133] Figure 13A illusfrates an antenna element 206 with a top portion 208,- a middle portion 210 and a bottom portion 212. The antenna element 206 is positioned atop a ground plane 214 and is grounded through a ground pad 216. The bottom portion 212 of the antenna element 206 is contoured to accommodate a shield 218 between the ground plane 214 and a portion of the bottom portion 212. In the illusfrated embodiment, the bottom portion 212 is provided with a raised left side, allowing the shield 218 to be positioned from approximately the middle of the bottom portion 212 and extended leftward. The positioning of the shield 218 improves the isolation of the antenna element 206, thereby improving performance.

[0134] Figure 13B illustrates an antenna element 220 with a top portion 222, a middle portion 224 and a bottom portion 226. The antenna element 220 is positioned atop a ground plane 228 and is grounded through a ground pad 230. The bottom portion 226 of the antenna element 220 is contoured to accommodate a shield 232 between the ground plane 228 and a portion of the bottom portion 226. In the illusfrated embodiment, the bottom portion 226 is provided with a raised central region, allowing the shield 232 to be positioned between the central region of the bottom portion 226 and the ground plane 228.

[0135] Figure 13C illustrates an antenna element 234 with a top portion 236, a middle portion 238 and a bottom portion 240. The antenna element 234 is positioned atop a ground plane 242 and is grounded through an extended ground pad 246. The bottom portion 240 of the antenna element 234 is entirely raised above the ground plane 242. A shield 248 is positioned between the bottom portion 240 and the ground plane 242 to provide improved shielding of the antenna element 234. In the illustrated embodiment, the shield 248 extends substantially the entire length of the bottom portion 240, but does not extend beyond the bottom portion 240.

[0136] Figure 13D illustrates an antenna element 250 with a top portion 252, a middle portion 254 and a bottom portion 256. The antenna element 250 is positioned atop a ground plane 258 and is grounded through an extended ground pad 260. The bottom portion 256 of the antenna element 250 is entirely raised above the ground plane 258. A shield 262 is positioned between the bottom portion 256 and the ground plane 258 to provide improved shielding of the antenna element 250. In the illusfrated embodiment, the shield 248 extends beyond one side of the bottom portion 240 to provide improved isolation of the antenna element 250.

[0137] Figure 14 illustrates another embodiment of an antenna element arrangement in accordance with the present invention. Ln the illusfrated arrangement 264, a planar CLMD antenna element 266 is positioned in the same plane as a ground plane 268. A line 270, such as a micro-strip line or a coplanar waveguide, for example, is provided to feed power to the antenna element 266. The antenna element 266 is grounded through a ground pad 272 to the ground plane 268. Thus, a very low profile, highly efficient and isolated antenna element arrangement is achieved.

[0138] Figure 15A illustrates another embodiment of an antenna element arrangement for achieving a very low profile and improved efficiency and isolation. In the illusfrated arrangement 274, a planar CLMD antenna element 276 is positioned in the same plane as a ground plane 278. A line 280, such as a micro-strip line or a coplanar waveguide, for example, is provided to feed power to the antenna element 276. In this embodiment, the antenna element 276 is grounded to the ground plane 268 through a pair of ground pads 282 for improved grounding.

[0139] Figure 15B illusfrates yet another embodiment of an antenna element arrangement for achieving a very low profile and improved efficiency and isolation. In the illustrated arrangement 284, a planar CLMD antenna element 286 is positioned in the same plane as a ground plane 288. The ground plane 288 is provided with a cutout 290 that is sufficiently large to accommodate the antenna element 286 therein. Thus, the antenna element 286 is surrounded on three sides by the ground plane. Positioning the antenna element 286 in this configuration provides improved isolation. The antenna element 286 is grounded to the ground plane 288 through a pair of ground pads 292. [0140] Figures 16A and 16B illusfrate further embodiments of antenna element arrangements in accordance with the present invention. In these embodiments, multiple antenna elements may be provided in a single, low-profile arrangement.

[0141] Figure 16A illustrates an antenna element arrangement 294 having a ground plane 306. The ground plane 306 is provided with a plurality of cutouts 296, 298. In the illusfrated embodiment, the ground plane 306 is provided with two cutouts 296, 298 positioned in two corners of the rectangular ground plane 306. In other embodiments, any number of cutouts may be provided, and the cutouts may be positioned at locations other than corners.

[0142] The arrangement 294 also includes a plurality of CLMD antenna elements 300, 302. The antenna elements 300, 302 are positioned in a coplanar manner with the ground plane 306 and within the cutouts 296, 298, respectively. This configuration improves the isolation of the antenna elements 300, 302 and results in a low-profile arrangement. Each antenna element 300, 302 is grounded to the ground plane 306 through ground pads 304 and is provided with power through feed lines 308. Thus, the illustrated arrangement 294 results in a low profile and improved isolation. Providing multiple antenna elements, such as antenna elements 300, 302 provides the arrangement with increased diversity.

[0143] In the arrangement illustrated in Figure 16A, the antenna elements 300, 302 are positioned in a mirrored configuration with the bottom portion of each being faced toward the bottom portion of the other.

[0144] Figure 16B illustrates another embodiment of an antenna element arrangement for providing low profile, improved isolation and larger bandwidth. The illustrated arrangement 310 is provided with a ground plane 312 having a plurality of cutouts 314, 316. The arrangement 310 also includes a plurality of CLMD antenna elements 318, 320, positioned in a coplanar manner with the ground plane 312 and within the cutouts 314, 316, respectively. Each antenna element 318, 320 is grounded to the ground plane 312 through ground pads 322. Ln the arrangement illustrated in Figure 16B, the antenna elements 318, 320 are positioned in a mirrored configuration about a center axis of the ground plane 312 with a side of each facing a side of the other. In other embodiments, the antenna elements may be positioned in various configurations, including positioning the antenna elements orthogonal to each other or at various angles.

[0145] Figure 17 illustrates another embodiment of an antenna element arrangement in accordance with the present invention. In the illusfrated arrangement 324, a CLMD antenna element 326 is positioned in a coplanar manner with a ground plane 328 to provide a low profile. The antenna element 326 includes a top portion 330, a middle portion 332 and a bottom portion 334. A component 336 is positioned in the region between the middle portion 332 and the bottom portion 334. The component may be any component such as electrical components including passive and active components such as capacitors, resistors and chipsets. In other embodiments, the component may be positioned between the top plate 330 and the middle plate 332. In additional embodiments, more than one component may be positioned within the antenna element. In this manner, the footprint of the antenna element may be used to accommodate the components, thereby conserving valuable space in small devices.

[0146] Figures 18a-b illustrate respective three-dimensional and side views of one embodiments of a capacitively loaded magnetic dipole antenna 599. In one embodiment, antenna 599 comprises a first 501, a second 502, and a third 503 portion. In one embodiment, the first portion 501 is coupled to the third portion 503 by a first coupling portion 511, and the third portion 503 is coupled to second portion 502 by a second coupling portion 512. Ln one embodiment, antenna 599 comprises a feed area, generally indicated as feed area 509, where input or output signals are provided by a feed line 508 that is coupled to the third portion 503. In one embodiment, the first coupling portion 511 and the second coupling portion 512 are disposed relative to each other in a generally parallel relationship. In one embodiment, first portion 501, second portion 502, and third portion 503 are disposed relative to each other in a generally parallel relationship. In one embodiment, first portion 501, second portion 502, and third portion 503 are disposed relative to each other in a generally coplanar relationship. In one embodiment, the portions 501, 502, and 503 are generally orthogonal to portions 511 and 512. Ln one embodiment, one or more of portions 501, 502, 503, 511, 512 are disposed in a generally orthogonal or parallel relationship relative to a grounding plane 506. It is understood, however, that the present invention is not limited to the described embodiments, as in other embodiments portions 501, 502, 503, 511, 512 may be disposed relative to each other and/or grounding plane 506 in other geometrical relationships and with other geometries. For example, first portion 501 may be coupled to third portion 503, and third portion 503 may be coupled to second portion 502 by respective coupling portions 511 and 512 such that one or more of the portions are disposed relative to each other in non-parallel, non-orthogonal, and/or non-coplanar relationships. In one embodiment, portions 501, 502, 503, 511, and 512 may comprise conductors. The conductors may be shaped to comprise one or more geometry, for example, cylindrical, planar, etc., or other geometries known to those skilled in the art. The conductors may be flexible, rigid, or a combination thereof.

[0147] In one embodiment, third portion 503 is disposed coplanarly with, or above, grounding plane 506. In one embodiment, third portion 503 is electrically isolated from grounding plane 506, other than where third portion 503 is coupled to grounding plane 506 at the grounding point 507. [0148] It is identified that third portion 503 may include one or more portion that is shaped to comprise other geometries, for example, a linear geometry, a curved geometry, a combination thereof, etc.

[0149] It is also identified that antenna 599 may be modeled as a radiative resonant LC circuit with a capacitance (C) that corresponds to a fringing capacitance that exists across a first void that is bounded generally by first portion 501 and second portion 502, and which is indicated generally as capacitive area 504; and with an inductance (L) that corresponds to an inductance that exists in a second void that is bounded generally by the second portion 502 and third portion 503, and which is indicated generally as inductive area 505.

[0150] It is further identified that the geometrical relationship between portions 501, 502, 503, 511, 512, and the gaps formed thereby, may be used to effectuate an operating frequency about which the antenna 599 resonates to radiate or receive a signal.

[0151] Figure 18C illustrates a three-dimensional view of an embodiment of a capacitively loaded magnetic dipole antenna 598. Some aspects of antenna 598 are similar to embodiments of antenna 599 described previously above and may be understood by those skilled in the art by referring to the description of antenna 599. However, it is identified that at least one aspect of antenna 598 differs from that of antenna 599. For example, in one embodiment, third portion 53 is defined by a length that is longer than a straight-line distance

(c) between a first end (a) and a second end (b) of the third portion. Ln the illusfrated embodiment, third portion 503 includes linear portions that are coupled in alternating orthogonal orientations. In one embodiment, the linear portions are disposed in generally parallel and/or orthogonal relationships relative to a grounding plane 506. It is identified that third portion 503 may include one or more portion that comprises or is coupled to comprise other geometries, for example, a linear geometry, a curved geometry, a combination thereof, etc. [0152] In one embodiment, portion 501, portion 502, and portion 503 are coupled to a substrate 515. In one embodiment substrate 515 comprises a high dissipation factor substrate, for example, a FR4 subsfrate known by those skilled in the art. In one embodiment, subsfrate 515 is defined by an outer periphery 516 and by an inner periphery 517, and the inner periphery defines a void within the substrate. In one embodiment, the capacitive area 504 generally spans the void.

[0153] It is identified that by coupling the first portion 501 and second portion 502 to a high dissipation factor substrate 515 such that the capacitive area 504 spans the void 517, the capacitance of antenna 598 may be increased over that of the capacitance of antenna 599. As compared to a capacitance of the antenna 599, an antenna 598 that has an equivalent capacitance may be provided to comprise a smaller form-factor/profile, for example, as measured in a direction orthogonal to grounding plane 506.

[0154] It is also identified that by providing a third portion 503 that comprises a length that is longer than a straight line distance (c) between the first end (a) and the second end (b) of the third portion, the antenna 598 inductance in the inductive area 505 may be increased over that of the inductance of the antenna 599. As compared to an inductance of antenna 599, an antenna 598 that has an equivalent inductance may be provided to comprise a smaller form- factor/profile, for example, as measured in a direction orthogonal to grounding plane 506.

[0155] Figure 19 illustrates a three-dimensional view of a capacitively loaded magnetic dipole antenna 597. In one embodiment, antenna 597 comprises a first 501, a second 502, and a third 503 portion. It is identified that antenna 597 may be modeled as a radiative resonant LC circuit with a capacitance (C) that corresponds to a fringing capacitance that exists in a capacitive area 504 that is bounded generally by first portion 501 and second portion 502; and with an inductance (L) that corresponds to an inductance that exists in an inductive area 505 that is bounded generally by the second portion 502 and the third portion 503. In one embodiment, the first portion 501 is coupled to the third portion 503 by a first coupling portion 511, and the third portion 503 is coupled to a second portion 502 by a second coupling portion 512. In one embodiment, antenna 598 comprises a feed line 508 coupled to the third portion 503 where input or output signals are provided.

[0156] Some aspects of antenna 597 are similar to embodiments of antenna 599 described previously above and may be understood by those skilled in the art by referring to the description of antenna 599. However, it is identified that at least one aspect of antenna 597 differs from that of antenna 599. For example, in one embodiment, third portion 503 is defined by a length that is longer than a straight-line distance (c) between a first end (a) and a second end (b) of the third portion. Figure 19a also illusfrates an embodiment of antenna 598 wherein third portion 503 is disposed in a generally non-coplanar relationship relative to the generally coplanar relationship of the first portion 501 and second portion 502. In one embodiment, third portion 503 may be disposed in a plane that his generally coplanar with, or above, a grounding plane 506. Ln one embodiment, third portion 503 may be electrically isolated from the grounding plane 506 other than where third portion 503 is coupled to grounding plane 506 at grounding point 507. It is identified that third portion 503 may include one or more portion that comprises or is coupled to comprise other geometries, for example, a linear geometry, a curved geometry, a combination thereof, etc.

[0157] In one embodiment, the grounding plane 506 and/or one or more portion of third portion 503 may be disposed in a plane that is generally orthogonal to a coplanar relationship of the first portion 501 and the second portion 502. In one embodiment (not illustrated), the grounding plane 506 and/or one or more portion of third portion 503 may be disposed in a plane that is in a generally angular relationship relative to a substrate 515, which first portion 501 and second portion 502 are coupled to. In one embodiment, the angular relationship of third portion relative to subsfrate 515 may be between 0 and 180 degrees. In one embodiment, substrate 515 comprises a high dissipation factor subsfrate, for example, a FR4 subsfrate. In one embodiment, subsfrate 515 is defined by an outer periphery 516 and by an inner periphery 517, and the inner periphery defines a void within the substrate. In one embodiment, the capacitive area 504 spans the void.

[0158] It is identified that by coupling the first portion 501 and second portion 502 to a high dissipation factor substrate 515 such that the capacitive area 504 spans the void, the capacitance of antenna 597 maybe increased over that of the capacitance of antenna 599. As compared to a capacitance of antenna 599, an antenna 597 that has an equivalent capacitance may be provided to comprise a smaller form-factor/profile.

[0159] It is also identified that by providing a third portion 503 that comprises a length that is longer than a straight line distance (c) between the first end (a) and the second end (b) of the third portion, the antenna 597 inductance in the inductive area 505 may be increased over that of the inductance of antenna 599. As compared to a capacitance of antenna 599, an antenna 597 that has an equivalent capacitance may be provided to comprise a smaller form- factor/profile.

[0160] It is also identified that by providing a third portion 503 that comprises a length that is longer than a straight line distance (c) between the first end (a) and the second end (b) of the third portion, the antenna 597 inductance in the inductive area 505 may be increased over that of the inductance of antenna 599. As compared to an inductance antenna 599, an antenna 597 that has an equivalent inductance may be provided to comprise a smaller form- factor/profile.

[0161] Figures 20a-b illusfrate three-dimensional views of embodiments of an capacitively loaded magnetic dipole antenna 596 and 595. In one embodiment, the first portion 501 is coupled to the third portion 503 by a first coupling portion 511, and the third portion 503 is coupled to second portion 502 by a second coupling portion 512. In one embodiment, antenna 596 comprises a feline 508 coupled to the third portion 503 where input or output signals are provided

[0162] Some aspects of antenna 596 and 595 are similar to embodiments of antenna 599 described previously above and may be understood by those skilled in the art by referring to the description of antenna 599. However, it is identified that at least one aspect of antenna 596 and 595 differs from that of antenna 599. For example, in one embodiment, third portion 503 is defined by a length that is longer than a straight-line distance (c) between a first end (a) and a second end (b) of the third portion. Figures 20a and 20b also illusfrate embodiments wherein at least one portion of the third portion 503 is disposed in a generally coplanar relationship relative to the generally coplanar relationship of the first portion 501 and second portion 592. It is identified that third portion 503 may include one or more portion that comprises or is coupled to comprise other geometries, for example, a linear geometry, a curved geometry, a combination thereof, etc.

[0163] Figures 20a-b also illustrate embodiments wherein at least one portion of third portion 503 may be disposed in a plane that is generally coplanar with, or above, a grounding plane 506. In one embodiment, third portion 593 is electrically isolated from the grounding plane 506 other than where third portion 503 is coupled to grounding plane 506 at a grounding point 507.

[0164] In one embodiment (not illustrated), the grounding plane 506 and/or at least a portion of third portion 503 may be disposed in a plane that is in an angular relationship relative to a coplanar relationship of first portion 501 and second portion 502. In one embodiment, the angular relationship relative to substrate 515 and may be between 0 and 180 degrees. [0165] In one embodiment subsfrate 515 comprises a high dissipation factor substrate, for example, a FR4 substrate. In one embodiment, substrate 515 is defined by an outer periphery 516 and by an inner periphery 517, and the inner periphery defines a void within the subsfrate. In one embodiment, the capacitive area 504 generally spans the void.

[0166] It is identified that by coupling the first portion 501 and second portion 502 to a high dissipation factor substrate 515 such that the capacitive area spans the void 517, the capacitance of antennas 596 and 595 may be increased over that of the capacitance of antenna 599. As compared to a capacitance of antenna 599, an antenna 596 and 595 that has an equivalent capacitance may be provided to comprise a lower form-factor/profile.

[0167] It is also identified that by providing a third portion 503 that comprises a length that is longer than a straight line distance (c) between the first end (a) and the second end (b) of the third portion, the inductance of antenna 596 and 595 that has an equivalent inductance may be provided to comprise a lower form-factor/profile.

[0168] Figure 23 illustrates a single-mode capacitively loaded antenna. If we assume that the structure in Figure 23 can be modeled as a Lid circuit, then Ci is the capacitance across gap g. Inductance Li is mainly contributed by the loop designated by the numeral 702. The gap g is much smaller than the overall thickness of the antenna. The presence of only one LC circuit limits this antenna design to operating at a single frequency.

[0169] Figure 24 illustrates a dual-mode antenna based on the same principles as the antenna shown in Figure 23. Here, a second antenna element is placed inside the first antenna element described above. This allows tuning one to a certain frequency fi and the other one to another frequency f₂. The two antennas have a common ground, but different capacitive and inductive elements. [0170] Figure 25 illustrates a multimode antenna with shared inductances ^~_\ and L₂. and discrete capacitances Ci, C_2j and C₃. The antenna comprises several antenna elements.

[0171] One embodiment of the present invention relates to an antenna with the radiating elements and the conductor lying in substantially the same plane. The radiating elements and the planar element have a thickness that is much less then either their length or width; thus they are essentially two dimensional in nature. Preferably the antenna structure is affixed to a substrate. Figure 26 illusfrates an antenna 10 in accordance with the principles of the present invention that is formed flat on a subsfrate 712. The antenna is substantially two-dimensional in nature. The antenna comprises a planar conductor 714, a first parallel elongated conductor 716, and a second parallel elongated conductor 718. The planar conductor is positioned in the same plane as the electric field, known as the E-plane. The E-plane of a linearly polarized antenna contains the electric field vector of the antenna and the direction of maximum radiation. The E-plane is orthogonal to the H-plane, i.e. the plane containing the magnetic field. For a linearly polarized antenna, the H-plane contains the magnetic field vector and the direction of maximum radiation. Each of elongated conductors 716 and 718 are electrically connected to the planar conductor 714 by respective connecting conductors 720 and 722. Antenna 710 comprises elongated conductors 716 and 718 that are in the same or substantially the same plane as the planar conductor 714. The gap between the elongated conductor 716 and the elongated conductor 718 is the region of capacitance. The gap between the elongated conductor 716 and the planar conductor 714 is the region of inductance. In a preferred embodiment, the space between the first elongated conductor 716 and the second elongated conductor 718 is much less than the space between the first elongated conductor 716 and the planar conductor 714.

[0172] In an alternative embodiment, shown in Figure 26, the radiating element and the conductor may be isolated. Ln Figure 27, a grounded planar conductor 732 is isolated from a radiating element 730 by an etched area 734. An antenna feed 736 is supplied and a return for the ground 738 is supplied. The antenna feeds 736, or feed lines, are transmission lines of assorted types that are used to route RF power from a transmitter to an antenna, or from an antenna to a receiver. In accordance with the principles of the present invention any of the antenna structures discussed herein could utilize an etched area or other means to isolate the radiating element or elements.

[0173] Another embodiment of the present invention relates to the use of the antenna structure previously described having an essentially two-dimensional structure, in combination with another planar conductor. The second planar conductor may be located on a opposite face of the substrate. Preferably, the two planar conductors are substantially parallel to each other. Figures 28A-28C show an antenna 740 with planar conductors 744 and 746 on opposite sides of the subsfrate 742. Vias 750 and 752 provide the antenna feed and shorts to ground, respectively. The vias 750 and 752 connect the radiating elements to the planar conductor 746.

[0174] In another embodiment, the antenna structure may utilize more than one radiating element. The radiating elements may be arranged side-by-side as showing in Figures 29 A- 29C. Figures 29A-29C show a dual frequency antenna structure, similar to the single element structure of Figures 28A-28C The antenna structure has radiating elements 760 and 762 arranged side-by-side. Each radiating element has vias connecting the radiating element to the planar conductor on the opposite face of the subsfrate. The planar conductors are substantially parallel to each other.

[0175] Alternatively, the radiating structures may be placed in a nested configuration as shown in Figure 30. Figure 30 shows another dual frequency arrangement implementing the design of Figure 24 on a substrate in a manner similar to Figure 26. In yet another embodiment of the present invention, the antenna structure may utilize three or more radiating elements. The radiating elements may all be located on the same face as the planar conductor. Figure 31 shows an antenna structure similar to that of Figure 30, but with an additional conductor 770 to increase the frequency diversity.

[0176] Figures 32A-32B show an antenna structure on a subsfrate 780. Face A of subsfrate 780 carries a three frequency antenna structure as shown in Figure 731. Face B of subsfrate 780 carries a single frequency antenna structure as shown in Figure 25, although alternatively this could also be a multifrequency structure or any combination of single and multifrequency structures.

[0177] In an another embodiment, the antenna structure may comprise conductors on any of the faces of the substrate. The conductors may be located in parallel and opposite arrangements or asymmetrically. Figures 33A-33B show an antenna structure 790 with conductors formed, such as by conventional printed circuit methods, on the edges as well as the face surface of the substrate 792. This allows even more space savings in certain packaging configurations.

[0178] In yet another embodiment, more than one substrate may be used. As shown in Figures 34A-34B, an second subsfrate bearing additional conductors can be utilized. The second substrate may be located perpendicular to the first subsfrate. As shown in Figures 34A-34B, a primary subsfrate 800 carries a multifrequency antenna structure, such as the one shown in Fig. 31. A secondary subsfrate 802 is mounted substantially perpendicular to the primary substrate. The substrate 802 carries a single frequency antenna structure, although alternatively this too could be a multifrequency structure.

[0179] In addition, in accordance with the principles of the present invention more than one secondary substrate may be utilized. Figures 35A-35B show additional arrangements, similar to Figures 34A-34B, wherein a plurality of secondary substrates, each carrying respective antenna structures, are mounted on a primary substrate.

[0180] Furthermore, the secondary substrate may be arranged in any configuration, not only in perpendicular positions. Figure 36 illustrates an antenna 810 on a substrate 812 that is extended relative to substrate 814. This allows installation of the antenna in an enclosure with a shape that just allows an antenna along the side of the enclosure.

[0181] Figure 37 illusfrates a configuration similar to that of Figure 36, but with two antennas for frequency diversity.

[0182] An antenna structure in accordance with the principles of the present invention may be integrated into an electronic device. The previously discussed benefits of the present invention make such an antenna structure well suited to use in small electronic devices, for example, but not limited to mobile telephones. Figure 38 shows the antenna structure of Figure 37 housed within an enclosure, such as the case of a mobile telephone or other electronic device.

[0183] Figure 39 illusfrates a configuration similar to that of Figure 37, but with four radiating elements, including elements carried on secondary substrates 820 and 822.

[0184] Figure 40 shows the antenna structure of Figure 39 housed within an enclosure, such as the case of a mobile telephone or other electronic device. The low profile of the antenna of the present invention allows for the antenna to be placed easily within electronic devices without requiring -a specifically dedicated volume.

[0185] Figure 41 illusfrates a circuit board 130 with radiating elements 832 and 834 disposed at opposite ends thereof. Similarly, in Figure 42, an electronic device, such as a laptop computer 840, is configured with a plurality of radiating elements. Owing to their construction, the radiating elements may be arranged within the computer wherever space is available. Thus, the design of the computer housing need not be dictated by the antenna requirements.

[0186] In yet another alternative embodiment, the antenna structure may comprise grooves. The grooves may be partially or completely through the substrate in various locations, such as between the radiating elements. Figure 43 illusfrates an antenna of the type generally shown in Figure 27. The antenna is formed, such as by conventional printed circuit techniques, on a substrate 850. A groove 852 is milled partially or completely through the substrate in the capacitive region of the antenna to improve the efficiency of the antenna.

[0187] Figure 44 illustrates the same concept shown in Figure 43, but in the case of a multifrequency antenna. Here, a plurality of grooves 862 are milled into substrate 860 between each pair of radiating conductors.

[0188] The antenna structures in accordance with the principles of the present invention may be made by any means known in the art such as the use of traditional circuit printing. Figure 45 illusfrates an alternative method for fabricating an antenna in accordance with the present invention. Rather than etching the antenna pattern on a printed circuit board, here the antenna is etched on a metallic film that is then molded in plastic. The resulting structure may be attached in various ways to a circuit board or to a device enclosure.

[0189] Accordingly, while embodiments and implementations of the invention have been shown and described, it should be apparent that many more embodiments and implementations are within the scope of the invention. Therefore, the invention is not to be restricted, except in light of the claims and their equivalents.

[0190] Wireless communication systems and devices operating in one or more frequency bands and utilizing one or more embodiments described herein are considered to be within the scope of the invention, for example, systems and devices such as PDAs, cell phones, etc. [0191] While particular embodiments of the present invention have been disclosed, it is to be understood that various different modifications and combinations are possible and are contemplated within the true spirit and scope of the appended claims. There is no intention, therefore, of limitations to the exact abstract or disclosure herein presented.

[0192] Thus, it will be recognized that the preceding description embodies one or more invention that may be practiced in other specific forms without departing from the spirit and essential characteristics of the disclosure and that the invention is not to be limited by the foregoing illustrative details, but rather is to be defined by the appended claims.