Untitled record

Artificial Grounding of Parts of a Radio Frequency Device Patent 864280 In the patent 864,280 an arrangement for the artificial earthing of high frequency arrangements is proposed, which consists of tuned links whose dimensions are smaller than 2./¢.

In the embodiments shown in patent 86: 128o, one or more such tuned members of a concentrated inductance (in the form of a coil) and a concentrated capacitance, e.g. B. end plate, mounted on the outer cable sheath. These creating the short in the space, on 2 (q. Resonance tuned links are connected to the cable through their concentrated inductance, while there is no connection between their other ends.

The invention relates to the constructive implementation and an advantageous development of such grounding arrangements and is that an arrangement is used, which is composed of radial elements acting as inductors and from the outer ends of these radial elements connecting elements, which act as space capacity, composed wherein the inductance or capacitance of these elements is so dimensioned that there is a vote for the wavelength to be ground.

The invention is described in detail with reference to the drawing. The Fig. Z shows an annular construction, which: is provided with a hub-like center A `from which emanate four spoke-like arms B1, B2, B3, B4, which are interconnected at their outer ends by a ring C. The whole construction is made of metal. The ground potential is to be established at the point A, and this is achieved by the fact that the elements B and C are suitably tuned. The spokes B1, B2, etc. act as inductances which connect the ring capacitance C with the point A. The frequency for which an effective grounding is made, that is the frequency; in which the inductance of the spokes resonates with the space capacity of the ring can be influenced by the following magnitudes: r. the diameter of the ring; 2, the cross-section of the individual spokes (the thinner the spokes, the greater the inductance; 3. the number of spokes which act as inductors connected in parallel (two or more spokes arranged one above the other can be used); q .. the effective cross-section of the ring (the larger the cross-section, the greater the space capacity, it may therefore also be provided in addition to outward approaches to increase the space capacity at the ring).

The grounding device shown in Fig. 2 may be constructed of metal, wherein - the individual elements are joined together by welding or by any other suitable method, thus resulting in an arrangement of good mechanical strength.

One such arrangement, which is for example intended to operate at a frequency of 6oMHz, consists of a copper ring consisting of one ½ inch wide strip and having 4o inch diameter and three spokes made of 314 inch copper strip ,

Fig. 2 shows an arrangement which is similar in construction to the arrangement of Fig. Z, but which has the further advantage that it is tunable. For this purpose, the four spokes Bi to B4 are made variable in length by telescoping or other suitable construction. To determine in any position clamping screws od. Like. Be provided. Of course, the ring C is also divided in this arrangement, so that at j eder spoke a ring portion is attached.

Fig. J shows a further embodiment, which, however, does not have as great a mechanical strength as the previously described arrangements. Here, the four arms extending from the center A are bent at right angles at a certain distance while the ring C is omitted. To adjust serve telescopically on the ends of the bent arms patch slidable sleeves. Fig. Q. shows in perspective view a further embodiment of the invention, which is shown in Fig. S in side view. Here z means an antenna whose outer conductor A is at the position q. should be earthed. At this point, three obliquely downward rods are Bi; B2, B3, the outer ends of which are interconnected by length-adjustable telescopic tube constructions Cl, C2, C3. These telescopic outer tubes each have a clamping screw at point D, by which the length can be determined. The dimensions of the individual elements of this construction are suitably chosen so that effective grounding at point q. In an arrangement according to the last-described embodiment, which was to operate at 76 MHz, the bars forming the triangle would be 39 inches long, while the bars leading from the triangle tips to the center would be 22 inches long. The inclination angle downwards against the outer conductor of an antenna feed line of 21 '' inch diameter was 7g °, while all bars were made of 1/3 inch copper tube.

The arrangements described are particularly suitable for use in conjunction with a quarter-wave antenna, which z. B. is mounted on the top of the mast of a ship or at another elevated location at which a ground through a short wave grounding line is not feasible. The arrangements described can be used in quarter-wave antennas or in other types of antennas fed with a coaxial power line. In addition to the end of the outer conductor and other points of the outer conductor can be connected to such an arrangement to the excitation of sheath waves. to avoid.

The invention may also be used to keep out interfering waves from a radio receiver which is in the vicinity of a shortwave transmitter. It is known that in receivers operating on the radio wave range, interference occurs in the conventional antenna forms when a shortwave transmitter is in the vicinity. In order to avoid these disturbances, one can equip the antenna and / or the antenna feed line with arrangements according to the invention, which are tuned to the wavelength of the jammer. In this way, the interference waves are damped so that they can not penetrate into the receiver. Also, to avoid ignition problems in motor vehicles, such as automobiles and aircraft, the invention can be used advantageously.