DE1217466B - Polarizer for microwaves - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. CL:

HOIp

H 03 h

German class: 21 a4 - 74

Number:
File number:
Registration date:
Display day:

M54979IXd / 21a4
December 1, 1962
May 26, 1966

The invention relates to polarizers for microwaves, in particular to polarizers for optionally generation of linearly or elliptically polarized waves. In the following, the The term "elliptically polarized" is used in a broader sense than is usually used, so that in it the The term "circularly polarized" is included as a particularly important special case. The expressions "Polarizer" or "polarization arrangement" are used here in such a way that they represent arrangements or Devices for influencing the direction of polarization and / or the type of polarization of electromagnetic Include waves.

It is common practice in radar or other microwave systems, in conjunction with a re-sector to operate an adapted horn antenna fed by a suitable waveguide system will. It is also known that the requirement is made of this horn antenna, optionally linear or radiate circularly polarized waves. Such horn antennas usually have a rectangular, tapered cross-section, and when designing the horn antenna, the aspect ratio, d. H. the ratio of length to width of the horn opening, can be chosen so that an adaptation to The reflector with which the horn is operated takes place in order to achieve the best possible illumination of the reflector to reach. In the case of such rectangular horn radiators, the taper is thus in two on top of one another perpendicular planes usually unequal. This is why if you have operates such a horn antenna with circularly polarized waves, different phase shifts for the two mutually perpendicular components of the circularly polarized wave. To the Correction of the phase errors arising in this way is customary in one that feeds the horn antenna Section of a rectangular waveguide to provide a suitable phase element, which the required compensating phase shift between the two mutually perpendicular Wave components of the circularly polarized wave caused. Such a phase element can e.g. B. a metallic one or a dielectric rib protruding from a wall of the rectangular waveguide into its interior. Usually as a feed to the rectangular waveguide section containing the phase element a polarizer used e.g. B. from a section of a rotatable circular waveguide with a suitably shaped, diameter-like arranged in its interior, dielectric rib and is suitable, depending on the position of the polarizer, for microwaves

Applicant:

The Marconi Company Limited, London

Representative:

Dr.-Ing. B. Johannesson, patent attorney,

Hanover, Göttinger Chaussee 76

Named as inventor:

John Richard Mark,

Ronald Kenneth Walker, Chelmsford, Essex

(Great Britain)

Claimed priority:
Great Britain 14 December 1961

(44 872),

dated September 12, 1962

Round waveguide either linearly or circularly polarized To create waves. Such a typically known arrangement would be described in US Pat Order included (assuming a sending order, although this order is of course can also be used for receiving): a rectangular waveguide as a feed line, which is linearly polarized with Waves fed, a rotatable polarizer with circular cross-section, which has a dielectric rib or other known polarization elements and from the feed line via a transition piece is fed from rectangular to circular cross-section of a known type, referred to as a phase shifter Rectangular waveguide containing a phase influencing element and from the polarizer via a transition piece is fed from circular to rectangular cross-section of a known type, finally an adapted Horn antenna that is fed by the phase shifter. In this embodiment, the arrangement has the polarizer has a limited bandwidth within which it works satisfactorily because Polarizer and phase shifter are coordinated so that only at a predetermined frequency an exactly circularly polarized wave is produced at the mouth of the horn. The phase errors, which the polarizer causes at other frequencies, however, are not caused by the phase shifter eliminated because the position of the polarizer to

609 570/210

3 4

generation of circularly polarized waves of 45 ° with each other; if, on the other hand, the a *

is that the dielectric rib in it is an angle and output-side conductor units are parallel,

with the main axis planes of the horn antenna and there is no effective rotation of the polarization plane

of the rectangular waveguide containing the phase element achieved.

forms. As a result, the known arrangement has now become five embodiments of the invention

the great disadvantage that it is only explained within one of the drawings, of which

relatively narrow frequency band satisfactory Fig. 1 is a schematic perspective view

is working. The main object of the present invention is a polarizer arrangement according to the invention

well, to fix that disadvantage. represents that feeds a horn while

Based on a known microwave io Fig. 2 shows how the polar contained in Fig. 1

oscillator for the optional generation of elliptical sator can be executed.

including circularly polarized or linearly polarized. In all figures, the arrow controls the electrical

ized waves from linearly polarized waves, be ^- vector of the fed linearly polarized wave

standing out of a round waveguide section.

inserts between two rectangular waveguide sections 15 The arrangement according to FIG. 1 can be derived from

with the same orientation of the main axes, think of four building units, namely (in the

those of the one to feed the linearly polarized assumption that the arrangement as a transmission arrangement

th waves, which is operated in the round waveguide): a feed unit, denoted by

intersected an odd number of angularly AA '; a polarizer unit labeled BB ';

staggered conductor units arranged ao a phase shifter, denoted by CC and a

is the inside of the waveguide diameter-like horn antenna D.

enforce, the invention therefore proposes that the feed unit AA ' consists of a right

the angle between the central and the input corner waveguide A, which is known per se

lateral ladder unit is approximately 22.5 ° / and that transition piece A ' from rectangular to circular

the output-side conductor unit cut around the longitudinal axis 25 is formed in one piece. The polarizer

of the waveguide rotatable and optionally parallel to the unit BB ' consists of the polarizer B and one

conductor arrangement on the input side or around transition piece B ' from circular to rectangular

45 ° is rotated against this. cut. The polarizer B is shown in Fig. 1 only as

If circular or linearly polarized waves, cylinders are shown, while one embodiment

are to be generated, the phase shift 30 of the polarizer B in FIG. 2 is shown. The phase

of the shaft components to each other 90 °. slide CC consists of a rectangular waveguide

In a preferred embodiment of the invention section C, the main axes of which have the same orientation as those of the rectangular hollow conductor A, a rectangular hollow conductor containing a phase element and a metallic or dielectric rib C, conductor section, of which a pair of seks parallel to 35 or a similar, the phase influencing the input-side conductor unit of the round hollow element C in its interior, as it is in itself, and one with this rectangular waveguide is known. The horn antenna D is a normal connected horn antenna, whereby the rectangular hollow-tapered horn antenna with a rectangular cross conductor and the horn antenna together have the cut and an aspect ratio, the phase shift of 90 ° of the two 40 desired in practice is determined by the shape and arrangement cause of the wave components against each other. Reflector (not shown), which is connected to the horn

In one embodiment of the invention, there are spotlights that are illuminated. The phase element C is arranged in the conductor units of diameter-like, in a known manner so that the phase stands arranged metallic conductor elements., Slide CC in connection with the horn antenna D where the angle between the middle conductor element 45 the relative phase shift of 90 ° between and the input-side conductor unit of the round two perpendicular waveguide sections 22 _{S is} 5 °, while the off-components cause the parallel to the main aisle-side conductor unit - together with between axes of the adjacent rectangular waveguide C, the middle and the output-side conductor unit F i g. 2 shows an embodiment of the Polarisa approximately existing further conductor units - around 50 torB from Fig. 1. The polarizer contains two round waveguide shafts that can be rotated, so that the out-axial, similar round waveguide sections B 1 and the output-side conductor unit to the input-side B 2, which are thus connected to one another are that the down conductor unit can be adjusted either parallel or under a section B2 compared to section BX by an angle of 45 °. Although each waveguide axis common to the conductor can be rotated, the unit can consist of a single conductor element. However, this is not recommended. Rather, section B2 is indicated by dashed lines in FIG. 2, each conductor unit preferably consists of a circle.

Plurality of parallel, spaced metallic conductor elements in the fixed round waveguide section B 1, the teaching elements belonging to a conductor being arranged at a distance through unit two conductor units in a plane 60, of which the entrance is arranged. So you can, for example, in the circular waveguide in one side with BIl, the other with B12. Provide three ladder units with equal spacing. In the rotatable round waveguide section B 2, each of, for example, three diameter-like conductor units B 21, which are arranged in one plane, are arranged in a single conductor unit. All three directing entities B11, B12 and exist. As you can easily see, the fed 65 B 21 rotates have the same distance along the round shaft when passing through the round planed waveguide! longitudinal axis and are equal to each other, tes their plane of polarization by 45 °, if the one with each conductor unit three parallel in a plane and output-side conductor units at an angle, diameter-like metal tubes or rods

contains. The plane of the ladder unit B 11 forms an angle of 22.5 ° with the plane of the middle ladder unit B12. The level of the conductor unit B 21, on the other hand, depends on the position of the rotatable circular waveguide section B 2. If the horn antenna D (FIG. 1) is to emit circularly polarized waves, the rotatable waveguide section B 2 is rotated so far that the plane of the conductor unit B 21 forms an angle of 45 ° with the plane of the conductor unit B 11. Since the plane of the input-side conductor unit 511 forms a right angle with the electrical vector of the linearly polarized wave fed in via the feed unit AA ' , the wave exiting the circular waveguide section B 2 after passing the conductor unit B 21 is 45 ° in its plane of polarization compared to the The plane of polarization of the fed-in wave is offset. If the linearly polarized wave fed in is to be emitted by the horn antenna without changing the type of polarization (i.e. only as a linearly polarized wave), the rotatable circular waveguide section B 2 is rotated until the plane of the conductor unit 521 coincides with that of the conductor unit B 11. This position is indicated by dashed lines in FIG.

As can be seen, the polarizer works when it is in either of the two positions described above is brought twice a rotation of the plane of polarization with respect to the incident linear Vector by 22.5 ° each with a total rotation of 45 °. As a result, the reflections are on the consecutive Conductor units of the same size, so that with a suitable choice of the spacing of the conductor units can extinguish each other in a known manner. In one case, it rotates twice the plane of polarization in the same direction, so that a total rotation of 45 ° is achieved, while im In the other case, the two opposite rotation of the plane of polarization is canceled.

1 shows the following: If the polarizer B is operated in such a way that the wave at its output has the same polarization direction as the fed-in wave, this wave remains unchanged when passing through the rectangular waveguide C and the horn antenna D , so that on the mouth of the horn antenna D a linearly polarized wave is emitted, which has essentially the same polarization direction as the fed wave. However, if the polarizer B is operated in such a way that the polarization plane of the wave at its output is rotated by 45 ° with respect to that of the fed-in wave, the two mutually perpendicular components of the output wave in the following rectangular waveguide section C (with the phase element C) and the horn antenna D a relative phase shift of 90 °, so that at the mouth of the horn antenna D a circularly polarized wave is emitted.

It is easy to see that in the illustrated embodiments of the invention, the bandwidth, insofar as it relates to the generation of exact circular polarization, is essentially only determined by the combination of the phase shifter CC and horn radiator D.

In cases in which the polarization arrangement according to the invention is not intended to be used to emit polarized waves at the mouth of a horn antenna, the horn antenna is unnecessary and the rectangular waveguide C with the phase element C is designed so that it effects the desired phase shift.

Claims (4)

Patent claims: 1. Microwave polarizer for the optional generation of elliptical including circular polarized or linearly polarized waves from linearly polarized waves consisting of one Round waveguide section, inserted between two rectangular waveguide sections with the same orientation of the main axes, one of which is used to feed in the linearly polarized waves wherein in the circular waveguide section an odd number of angularly opposite one another offset conductor units is arranged, the inside of the circular waveguide like a diameter enforce, characterized in that the angle between the middle and the the input-side conductor unit is approximately 22.5 ° and that the output-side conductor unit rotatable around the longitudinal axis of the waveguide and optionally parallel to the conductor arrangement on the input side or can be adjusted rotated by about 45 ° against this. 2. Microwave polarizer according to claim 1 for the optional generation of circularly polarized or linearly polarized waves from linearly polarized waves, characterized by! that the phase shift of the mutually perpendicular wave components is 90 ° amounts to. 3. Microwave polarizer according to claim 2, characterized in that the rectangular waveguide section (C) following the output of the circular waveguide section (B) is equipped with a phase element (C) and connected to a horn radiator (D) and that this rectangular waveguide section together with the horn radiator caused the desired phase shift of 90 ° of the two wave components against each other. 4. Microwave polarizer according to one of claims 1 to 3, characterized in that each conductor unit made up of a multiplicity of parallel, spaced-apart metallic conductor elements consists, wherein the conductor elements belonging to a conductor unit lie in one plane. Considered publications:
German publication No. 1115 797. 1 sheet of drawings 609 570/210 5.66 © Bundesdruckerei Berlin