US2524830A

US2524830A - Beacon antenna system

Info

Publication number: US2524830A
Application number: US584596A
Authority: US
Inventors: Sidney B Pickles
Original assignee: Federal Telephone and Radio Corp
Current assignee: Federal Telephone and Radio Corp
Priority date: 1945-03-19
Filing date: 1945-03-19
Publication date: 1950-10-10
Anticipated expiration: 1967-10-10
Also published as: BE469846A; FR923933A; ES172871A1; CH273990A

Description

ct. 10, 1950 s. B. PKCKLES BEACON ANTENNA SYSTEM Filed March 19, 1945 e saaeses IN V EN TOR SIDNEY 5. PIC/(LES KZ-;;,

ATZWM Patented Oct. 10, 1950 BEACON ANTENNA SYSTEM Sidney B. Pickles, Jackson Heights, N. Y., assignor to Federal Telephone & Radio Corporation, New York, N. Y., a corporation of Delaware Application March 19, 1945, Serial No. 584,596

This invention relates to antenna systems and more specially to antenna systems for use in directive radio systems such as localizing, guiding, beacon systems and the like.

A principal object is to provide an improved antenna arrangement for controlling the field of radiation and non-radiation in a desired direction or directions.

The invention is in the nature of an improvement upon the antenna arrangement disclosed in my copending application, Serial No. 580,674, filed March 2, 1945. There is disclosed in that application a radiating beacon system wherein the directive antenna proper is provided with a special form of radiation shield and reflector whereby the directive radiated field pattern can be given one or more minimum field intensity regions which can be directed at desired angles without materially affecting the main directed beam action of the antenna.

Accordingly, it is another principal object of this invention to provide a novel radiation screen for directed beacon antennae, whereby the desired directive minima may be produced in the radiation pattern, while at the same time providing greater sharpening to the main directive beacon field.

A feature of the invention relates to a radiation screen for beacon antennae and the like wherein the screen is provided with a novel arrangement for terminating the ends of the screen to achieve improved directivity and field pattern control.

Another feature relates to a radiation screen for beacon antennae and the like comprising a series of screen conductors mounted in spaced array and with respect to the beacon antenna. These conductors have novel terminating means to render them substantially aperiodic at the beacon working frequencies.

A further feature relates to a radiation screen for antennae, comprising a wire network. which is provided with a series of auxiliary radiation absorption units for preventing standing waves in the main body of the screen at the antenna working frequencies, and without the necessity of employing relatively long terminating wires which approach the earth.

A further feature relates to a radiation screen for antennae, comprising a series of spaced superposed conductors whose ends are space-coupled to individual radiation absorbing terminal units to terminate said conductors in their characteristic impedances.

7 Claims. (01. 250-3s.5)

A further feature relates to a bi-part reflecting screen for antennae, comprising a main series of spaced reflector conductors and an auxiliary series of reflector conductors for controlling the resonance characteristics of the said main conductors at the antenna working frequencies.

A still further feature relates to a reflecting screen for antennae, comprising a series of spaced reflector conductors having their configuration designed to provide a terminating impedance equivalent to their characteristic impedance and without the necessity of employing extensive terminating wires for that purpose.

Other features and advantages not particularly set forth will be apparent after a consideration of the following detailed descriptions and the appended claims.

Inasmuch as the invention finds its primary utility in connection with a radio beacon system of the kind disclosed in said application, Serial No. 580,674, only those parts of an antenna and reflecting system will be described herein as are necessary to an understanding of the inventive concept. It will be understood however, that the disclosure of said application Serial No. 580,674 is to be taken, by reference, as part of the present disclosure.

In the drawing which shows certain preferred modes of practicing the invention:

Fig. 1 is a plan view of an antenna array and reflector-shield arrangement embodying principles of the invention.

Fig. 2 is a front elevation view of Fig. 1.

Fig. 3 is an elevational view showing a modification of Figs. 1 and 2.

Referring to Figs. 1 and 2, there is shown a series of horizontal loop antennae l, which may be supported in any suitable manner to provide the well-known broadside antenna array whereby a directed radiation field is produced. While the drawing shows a series of five antenna units, it will be understood that a greater or less number may be employed. Further, while the antennae are shown as of the loop type, any other well-known directive antenna units may be employed.

Suitably mounted rearwardly of the antenna, is a reflector-shield or screen comprising a series of spaced conductors 2, insulatingly mounted on posts 3 and 4. The distance D between the screen and the antenna array is preferably made one-half wave length or greater, while the length L of the screen may be from 4 to 8 wave lengths so as to provide the required shielding action rearwardly of the antennae. The wires 2 may be strung between poles 3 and 4, so as to be relatively close to each other, depending of course upon the particular screening and reflecting actions desired.

For the purpose of controlling the radiation resonance of the screen, and particularly so that no standing waves will be set up therein at the operating antenna frequencies, I have found that the individual wires 2 should be terminated at their ends so that their terminating impedance substantially matches the impedance of the wires proper. In my prior application Serial No. 580,674 this result has been achieved by extending the individual wires 2 asymptotically towards the earth. In order to achieve the necessary impedance with this prior arrangement, considerable ground area is required for the extended terminating wires. However, I have found that the desired results can be achieved without these relatively long extensions on the wires 2. For this purpose, there are mounted adjacent the ends of the wires 2, corresponding auxiliary screen members 5, 9, which can be insulatingly supported in any well-known manner on suitable posts 'i, 8. Each of the members 5, 6, may be in the form of a single straight conductor preferably of a half wave length, and each is mounted in front of a corresponding wire 2 of the main screen. The spacing and location of the wires 5 with respect to wires 2, can be varied to provide the desired phase and coupling ratio therebetween so as to achieve the desired impedance termination for the main screen wires. While the drawing shows the wires 5 displaced vertically with respect to the associated wires 2, it will be understood that, if desired, each wire 5 may be mounted in the same plane as the associated wire 2, or if desired, they may be mounted at any suitable angle with respect thereto.

It will be understood of course that, in accordance with accepted coupled section theory, the correct phasing to achieve the desired terminating impedance will be a function of the length L of the main screen and the coupling between the wires 2 and 5. It can be shown that the tightest coupling will be obtained when the main section wires 2 extend one-quarter wave length beyond the ends of auxiliary wires 5.

I have found that with the foregoing described arrangement, the auxiliary wires 5 have considerable directional properties, and when they are excited under control of the wires 2, they act as auxiliary radiators and therefore may be used to add small amounts of energy on the directed field pattern from the antenna I, thus giving additional control over the sensitivity and shape of the field pattern. It will be understood that while the drawing shows the auxiliary wires at each end of the screen equal in number to the main wires 2, one or more of these auxiliary wires may be deleted in order to produce special efiect on the field pattern.

Referring to Fig. 3, there is shown a modification of Figs. 1 and 2 for obtaining substantially the same results. Instead of controlling the terminating impedance of the wires 2 through the intermediary of separate spaced coupled radiator sections 5, this control may be effected without such separate members or in addition thereto. Thus, as shown in Fig. 3, the wires 2, instead of proceeding directly to their ends, are provided adjacent those ends with bent or partially looped sections 9 and 10. These sections 9 and I!) may be in the form of half loops. In effect therefore, the semi-loops 9 and I0 provide a quasi-discontinuity in the propagation characteristics of the wires 2 along their lengths, and the sections 9 and I0 perform substantially the same function as though the wires 2 (Fig. 1) had each a semi-loop conductor inserted therein from the back of the screen. In other words, the current propagated towards the screen terminations will flow around the bent sections 9 and H] which will cause the latter to act as auxiliary radiators. The phase of the radiation from these auxiliary radiators will, in accordance with accepted theory, be a function of the location of the bends along the length of the wires 2 and their location with respect to the antennae l, as well as a function of the impedance presented by the sections 9 and I0 themselves. While Fig. 3 shows the sections 9 and I0 offset in a vertical plane from the wires 2, it will be understood that these offset sections may be madein any other desired plane.

While certain particular embodiments have been disclosed herein, various changes and modifications may be made without departing from the spirit and scope of the invention. The examples given in the drawing are merely illustrative and not by way of limitation on the scope or utility of the invention.

What is claimed is:

1. An arrangement for controlling the radiation pattern of an antenna, comprising a radiation screen made of a series of horizontal wires mounted in spaced relation to the antenna, and means to control the aperiodicity of said screen at the antenna working frequencies, the lastmentioned means comprising screen terminating impedance means space-coupled to the extremities of said screen wires.

2. An arrangement for controlling the radiation pattern of an antenna, comprising a radiation screen made of a series of horizontal wires mounted in rearward spaced relation to the antenna, and means to terminate said screen in its characteristic impedance, the last-mentioned means comprising an auxiliary screen spacecoupled to the extremities of said radiation screen wires.

3. In combination, a directional antenna, a conductive network mounted rearwardly of said antenna and comprising a series of elongated spaced conductors, an impedance terminating means for said conductors comprising another series of short conductors mounted in radiationcoupled relation to the ends of said elongated conductors.

4. The combination according to claim 3 in which said elongated conductors are approximately 4 to 8 times the operating wave length of the antenna, and said short conductors are approximately one-half said wave length.

5. The combination according to claim 3 in which said ends of the elongated conductors extend beyond said short conductors by approximately one-quarter wave length.

6. In combination, a directional antenna, a conductive network mounted rearwardly of said antenna, said network comprising a first series of spaced horizontal wires and a second series of spaced horizontal wires mounted in spacecoupled relation to the end sections of the first series, the length of said second series of wires and their spacing with relation to the first series and with relation to said antenna being proportioned to render said network substantially aperiodic at the antenna operating frequencies.

7. The combination according to claim 6 in which said first series of Wires are mounted at least one-half wave length rearwardly of the antenna and said second series have a length approximately one-half the operating Wave 5 length of the antenna.

SIDNEY B. PICKLES.

REFERENCES CITED The following references are of record in the 10 file of this patent:

Number 6 UNITED STATES PATENTS Name Date Hahnemann June 17, 1930 Carter June 11, 1940 Alford Dec. 31, 1940 Gavitt May 12, 1942 Number Schelkunoff et al. Aug. 4, 1942 FOREIGN PATENTS Country Date France Mar. 2, 1931