US3594802A

US3594802A - Omnidirectional antenna having circumferentially spaced radiators with orthogonal polarization

Info

Publication number: US3594802A
Application number: US761198A
Authority: US
Inventors: Karl Koob
Original assignee: Bolkow GmbH
Current assignee: Bolkow GmbH
Priority date: 1967-09-22
Filing date: 1968-09-20
Publication date: 1971-07-20
Anticipated expiration: 1988-07-20
Also published as: GB1236270A; DE1591008B1; FR1583341A

Abstract

In an omnidirectional antenna of the type including plural individual radiators arranged around the circumferential periphery of a preferably cylindrical body whose diameter is large relative to the operating wave length of the antenna, the respective polarization directions of peripherally adjacent individual radiators are perpendicular to each other. The radiation patterns of the individual radiators overlap in the range of their respective half powers (3db-points). The antenna has a circular radiation characteristic formed by simple addition of the radiation patterns of the individual radiators.

Description

United States Patent Inventor Karl Koob Munich, Germany Appl. No. 761,198 Filed Sept. 20, 1968 Patented July 20, 1971 Assignee Bolkow Gesellschait mit beschrankter lrlaitung Ottobrunn, near Munich, Germany Priority Sept 22, 1967 Germany P 15 91 008.4

OMNIDIRECTIONAL ANTENNA HAVING CIRCUMFERENTIALLY SPACED RADIATORS WITI'I ORTIIOGONAL POLARIZATION 5 Claims, 4 Drawing Figs.

US. Cl 343/705, 343/D1G. 3, 343/799, 343/895 Int. Cl 1101:; 1/28 Field otSearch 343/705,

708, 756, 797, 778, 895, DIG. 3, 799

[56] References Cited UNITED STATES PATENTS 2,512,137 6/1950 Buchwalter et al. 343/799 3,188,640 6/1965 Simon et a1. 343/705 3,192,529 6/1965 Chatelain 343/708 3,438,038 4/1969 Marston 343/778 Primary Examiner--Eli Lieberman Attorney-McGlew and Toren ABSTRACT: In an omnidirectional antenna of the type in-' cluding plural individual radiators arranged around the circumferential periphery of a preferably cylindrical body whose diameter is large relative to the operating wave length of the antenna, the respective polarization directions of peripherally adjacent individual radiators are perpendicular to each other. The radiation patterns of the individual radiators overlap in the range of their respective half powers (3db-points). The antenna has a circular radiation characteristic formed by simple addition of the radiation patterns of the individual radiators.

PATENTEDJULPOISYE SHEET 1 OF 2 INVENTOR y Karl Koob 7Www/ M ATTORNEYS PATENTEUJULZOIB?! 3,594,802

SHEET 2 OF 2 Fig. 4

INVENTOR By KCII'l KOOb IWMVTJQ ATTORNEYS OMNIDIRECTIONAL ANTENNA HAVING CIRCUMFERENTIALLY SPACED RADIATORS WITI'I ORTIIOGONAL POLARIZATION BACKGROUND OF THE INVENTION Omnidirectional antennae of the mentioned type are known and are required, for example, in aviation and space flight, to communicate by signals with a missile rotating about its longitudinal axis, for example. Such a missile must have an antenna which, in a plane normal to its longitudinal axis, has a circ ular radiation characteristic.

The construction of such antennae becomes increasingly more difficult, particularly with boosters and satellites of modern space technology. Thus, on the one hand, the diameter of the antenna carrier, such as a booster or a satellite, becomes increasingly larger and larger and, on the other hand, increasingly shorter operating wave lengths are used for maintaining signal communications with the boosters and satellites. For example, the first stage of the Saturn rocket has a diameter of 6.7 m., and the signal communication required particularly for telemetry operations is operated with an operating frequency of 2.2 GHz. This results in a ratio of diameter to wave length D/A) of approximately 50.

If only a few individual radiators are arranged on the surface of a cylinder whose diameter is large relative to the operating wave length, there result, in the detennining plane for the radiation characteristic, and perpendicular to the cylinder axis, in certain directions, radiation minima which, in each case, are brought about by a phase opposition overlapping of the waves emanating from adjacent individual radiators.

To keep the minima in the radiation characteristic of the antenna as small as possible, the procedure hitherto has been to arrange, on the surface of such a cylinder, the largest possible number of individual radiators. Thus, for example, the omnidirectional antenna of the satellite TELSTAR, whose operating frequency is 6.39 Gl-Iz. and whose diameter is 88 cm. (D/)t=l9) consists of a ring of 72 closely positioned hornlike individual radiators. Such an antenna system, consisting of a large number of individual radiators, has, however, and precisely for applications in space technology, substantial disadvantages.

Thus, the large number of individual radiators results in a considerable additional weight and requires a large portion of the space available on the surface of the satellite. Moreover, uniform distribution of the high frequency energy through the individual radiators is difficult, dissipative, and achievable only with a considerable expense. Inspite of the above, the radiation pattern, in the determining plane, is mostly only insufficiently circular.

SUMMARY OF THE INVENTION This invention relates to omnidirectional antenna of the type including plural individual radiators arranged on the surface of a preferably cylindrical body whose diameter is large relative to the operating wave length of the antenna and, more particularly, to an improved and simplified omnidirectional antenna of this type.

The objective of the invention is to provide an omnidirectional antenna which, with a large ratio of the diameter of, for example, a cylindrical antenna carrier, to the operating wave length of the antenna, has as nearly as possible an ideal circular radiation characteristic, and without the necessity of continuously increasing the number of the individual radiators with an increasing ratio of diameter to wave length with the attendant disadvantages.

In accordance with the invention, this problem is solved, with several individual radiators of an omnidirectional antenna and arranged on the surface of a preferably cylindrical body whose diameter is large relative to the operating wave length of the invention, by providing that the respective polarization directions of peripherally adjacent individual radiators are perpendicular to each other, and that the respeclive radiation patterns of individual radiators overlap in the range of their respective half powers on 3 db.-points.

With this surprisingly simple improvement in an omnidirectional antenna of the type mentioned, it is assured that the respective polarization waves of adjacent individual radiators, and which are normal or perpendicular to each other, cannot influence one another or interfere with one another. The radiating energy of the overlapping radiation patterns of adjoining individual radiators are added so that an approximately ideal circular radiation characteristic of the entire antenna system, and regardless of the magnitude of the ratio of the diameter of the carrier to the wave length, is achieved.

If, in accordance with one embodiment of the invention, circularly or elliptically polarized helical radiators are used as the individual radiators are polarized in the opposite sense of rotation.

In accordance with another embodiment of the invention, the individual radiators can be designed as horn radiators or as dipole radiators.

Accordingly, an object of the invention is to provide an improved directional antenna of the type including plural individual radiators arranged on and around the peripheral surface of a shaped body whose diameter is large relative to the operating wave length of the antenna.

Another object of the invention is to provide such an omnidirectional antenna in which the respective polarization directions of peripherally adjacent individual radiators are perpendicular to each other.

A further object of the invention is to provide such an omnidirectional antenna in which the respective radiation patterns of individual radiators overlap in the range of their respective half powers or 3 db.points.

Still another object of the invention is to provide such an omnidirectional antenna in which the radiating energy of the overlapping radiation patterns of adjoining individual radiators add to each other so that an approximately ideal circular radiation characteristic of the entire antenna system is attained irrespective of the magnitude of the ratio of the diameter of the carrier to the wave length.

A further object of the invention is to provide such an omnidirectional antenna using individual radiators in the form of circularly or elliptically polarized helical radiators with adjoining individual radiators being polarized in the opposite sense of rotation.

Another object of the invention is to provide such an omnidirectional antenna in which the individual radiators are designed as horn radiators or as dipole radiators.

For an understanding of the principles of the invention, reference is made to the following description of typical embodiments thereof as illustrated in the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS In the Drawings:

FIG. 1 is a perspective view of an antenna system embodying the invention and utilizing horn radiators;

FIG. 2 is a perspective view of an antenna system embodying the invention and utilizing dipole radiators;

FIG. 3 is a perspective view of an antenna system embody- I ing the invention and utilizing helical radiators; and

FIG. 4 is a graphical illustration of the radiation pattern of antenna systems embodying the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS horn radiators are so designed or, respectively, fed, that the radiated electromagnetic waves of respective adjoining hom radiators, such as those of

horn radiators

2 and 3, are polarized perpendicularly or normal to each other. Thus, and as shown in FIG. 1, horn radiator 2 is polarized in a direction parallel to the axis of cylinder 1 and horn radiator 3 is polarized in a direction parallel to the diameter ofcylinder 1.

The embodiments of the antenna system shown in FIGS. 2 and 3 closely resemble that of FIG. 1. In FIG. 2, the horn radiators of FIG. 1 are replaced by individual dipole radiators, such as the dipole radiator 2' which is polarized parallel to a diameter of cylinder 1 and the dipole radiator 3' which is polarized parallel to the axis of cylinder 1.

In the embodiment of FIG. 3, the individual radiators are helical radiators, and the respective elliptical polarizations of adjacent radiators have opposite senses of rotation. Thus, for example, the helical radiator 2 is polarized clockwise and the helical radiator 3" is polarized counterclockwise. Since each elliptically polarized wave can be split up into two mutually perpendicular linear polarized waves, polarized helical radiators, which are polarized in the opposite sense of rotation, can also be considered as being radiators which are polarized perpendicularly to each other.

Since adjacent individual radiators must be polarized perpendicularly to each other, the number of individual radiators in all of the antenna embodiments can only be an even number. The radiation patterns 6, 7, 8 and 9 of the individual radiators, as shown in FIG. 4, must overlap each other at the respective half powers or 3 db.-points, since the circular radiation characteristic 10 of the overall antenna system, formed as the sun patterns is formed by simple addition of the radiation patterns of the individual radiators.

Basically, any even number of individual radiators is suitable for forming an antenna system embodying the invention.

Antenna embodying 2, 4 and 6 individual radiators are of special interest since an antenna system with too large a number ofindividual radiators would have part of the disadvantages of known antenna of this type. For the half power width Act of the radiation patterns of the individual radiators, there results, depending on the number n of individual radiators contemplated on the antenna carrier, the following value: Aer/degrees 360/n.

What I claim is:

1. In an omnidirectional antenna of the type including plural individual radiators arranged on and around the peripheral surface of a shaped aerodynamic vehicle whose diameter is a large multiple of the operating wave length of the antenna, the improvement comprising an even number of individual radiators, with the respective polarization directions of the radiation of peripherally adjacent individual radiators being perpendicular to each other and the respective radiation patterns of the individual radiators overlapping each other in the range of their respective half powers or 3 db.-points.

2. In an omnidirectional antenna, the improvement claimed in claim 1, in which the individual radiators have elliptic polarizations and the respective elliptic polarizations of peripherally adjacent individual radiators are polarized in the opposite sense of rotation.

3. In an omnidirectional antenna, the improvement claimed in claim I, in which the individual radiators are horn radiators.

4. In an omnidirectional antenna, the improvement claimed in claim 1, in which the individual radiators are dipole radiators.

5. In an omnidirectional antenna, the improvement claimed in claim 2, in which the individual radiators are helical radiators.

Claims

3. In an omnidirectional antenna, the improvement claimed in claim 1, in which the individual radiators are horn radiators.