Spurious electromagnetic-mode suppression arrangement in a waveguide installation.

p0001The invention relates to an arrangement for the removal of disturbing electromagnetic waveforms in waveguide systems with waveguide sections same or different rectangular cross-section, in which a one-mode filter forming surface resistance is arranged in a plate-shaped metal-coated dielectric support in the waveguide, which in cross-sectional center in the plane of the broad side extends over a suitable length in the axial direction of the waveguide. Such an arrangement is essentially known from DE-AS 1,244,259.

p0002In radio and satellite communications, it is important to use a low-loss power line as possible between devices and antennas. In transmission regions above 3 GHz waveguide therefore be used that operate in the fundamental region. At frequencies above 10 GHz is the attenuation of waveguides, which are operated in distinct frequency range, usually too high, so that is a significant loss to the transmitting and receiving energy at longer antenna connections. So z. B. is the damping of the duct R 220 in the range 18.7 GHz over 50 dB / 100m.

p0003One way to reduce the attenuation in waveguides, the operation of the line above its unambiguity limit.

p0004In DE 31 30 209 A1 a conduit for the transmission of electromagnetic energy is described in the microwave range rectangular with a hollow conductor or elliptical cross-section, working in a wide lying above its uniqueness limit frequency range and connected in its end regions each with a pyramid-shaped waveguide transition is the free end has a cross section of such dimensions that it is for information to be transmitted electromagnetic wave in the uniqueness range. This embodiment is directed in particular to a rectangular waveguide called SIRAL which operates in ambiguous low attenuation frequency range and damping of higher modes comprises a mode filter consisting held from one in the plane of the broad side lying centrally, in a cross section fully filling foam body damping plate. Losses and transmissible power can be greatly influenced by the foam material.

p0005The invention is based on the object of an arrangement of the type mentioned, a solution for possible losses of higher modes seamlessly transferring energy to create.

p0006This object is achieved according to the invention in such a way that the mode filter is divided into two half-mode filter of deden one each is used exhaustively in the respective end region of two to be connected waveguide sections flush, the only by applied to the inner wall of narrow lateral webs made of foam are held.

p0007Advantageous refinements and developments of the subject invention are disclosed in the dependent claims.

p0008The invention will be explained in more detail with reference to embodiments shown in the drawing.

p0009Show it<ul><li>Figures 1 and 2 a semi-mode filter for a waveguide in the front view and top view,</li><li>Figure 3 a semi-mode filter for a waveguide transition in a plan view,</li><li>Figures 4 and 5 into two partial representations assembly of semi-mode filters in two waveguide ends and </li><li>6 shows the connection of a hollow conductor end piece with a waveguide transition with used semi-mode filters.</li></ul>

p0010Higher modes that may arise in inhomogeneous Make a hollow pipe in addition to the fundamental wave type, cause resonance-like intrusions of transmission loss, which can degrade the transmission characteristics of the line. To mitigate the higher wave types mode filter according to the invention is provided which damps excited modes directly at its source and almost does not affect the modulated signal with the fundamental wave type.

p0011The mode filter, as shown in Figures 1 to 3, consists of a damping plate having a wall thickness of 0.05 to 2 mm, preferably 0.2 mm made from a dielectric substrate, in particular of glass fiber reinforced epoxy resin having a vapor-deposited metal layer, whose surface resistance 100 is to 600Ω. This damping plate is called the mode filter 1 for a straight waveguide section according to FIG 2 with 2, a mode filter 4 in the cone of a waveguide transition according to Figure 3 with 5. The damping plate 2.5 is in rectangular waveguide (SIRAL) in waveguide center parallel to the broad side of the waveguide arranged (perpendicular to the e vector of the fundamental wave type) and is only by small ridges of foam 3 and 6 held that rest on the narrow sides of the waveguide. These contribute very little to dampen the fundamental wave type, since the performance-leading cross-sectional area of ​​the waveguide remains free almost completely of disturbing and cushioning support material. The losses of the mode filter are therefore very low.

p0012The mode filter is inserted in the waveguide transitions at both ends of the line, allowing connection to devices and antennas, as well as in hollow conductor couplings for the connection of the waveguide sections of the same cross-sectional dimensions to wegzudämpfen that were produced at the small inhomogeneities of the waveguide modes.

p0013A particular advantage of the mode filter of the invention is that in a simple manner in each waveguide part a semi-mode filter can be inserted flush in the manufacture of a waveguide. The installation of this is shown in FIGS 4 and 5, first being inserted flush into the laterally offset waveguide ends 7, 8 on a half-mode filters 1 and then at the axis the same position of the waveguide ends the connection of the waveguide takes place (Figure 5). So therefore the desired during installation simple connection between the two waveguide interface is made possible easily by lateral overlaying pushing and subsequent coupling assembly. Flanges for connection of the two waveguide sections were not located in the simplified representation.

p0014Figure 6 shows a corresponding view of the connection of a waveguide 8 with a waveguide transition 9, wherein in the end portion at the interface in the hollow fiber end piece 8 a semi-mode filter 1 according to Figure 2 and the waveguide transition 9 a semi-mode filter is 4 inserted into a conical shape as shown in FIG. 3