JPH02260901A - Circularly polarized wave generator - Google Patents

Abstract

PURPOSE:To obtain a circularly polarized wave generator with simple constitution and with superior characteristics by installing two phase shifters where one of two orthogonal polarized waves is matched and the phase difference of both polarized waves comes to be 45 deg. in a waveguide and setting the distance of both phase shifters in such a way that the other polarized wave can be matched. CONSTITUTION:When dielectric boards 6 and 6' which are almost hexagonal are inserted in a plane including AA' of the waveguide and a waveguide axis as the phase shifters where the reflective coefficient of the polarized wave B is small and the phase shift amounts of the polarized wave A and the polarized wave B come to 45 deg., they come to the phase shifters where the reflection of the polarized wave B is small and the whole phase shift amount comes to 90 deg.. At that time, the size of the reflection of the polarized wave A changes in accordance with the interval (d) of two dielectric boards 6 and 6'. When the interval (d) is adjust in such a way that the reflected wave of the polarized wave A by the dielectric board 6 on an input-side and the reflected wave of the polarized wave A by the dielectric board 6' at the back of the board 6 are mutually compensated, reflection with respect to the polarized wave A becomes considerably small. Thus, the phase difference of the polarized wave A and the polarized wave B comes to 90 deg. in an output terminal, the sizes of transmission coefficients in both come to a value near '1', whereby the amplitude of the polarized waves A and B becomes equal.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to improvements in circularly polarized wave generators.

[Summary of the invention] By arranging two 45° phase shifters in the waveguide,
This is a circularly polarized wave generator that can be matched with each of two orthogonal polarized waves and has a phase shift difference of 90'' between both sides.

[Prior Art] FIG. 4 shows an example of a conventional circularly polarized wave generator, in which 1 is a circular waveguide and 2 is a dielectric plate. In this circularly polarized wave generator, in the L mode of one circular waveguide 1, polarized waves with an electric field in the AA' direction are polarized waves A, and polarized waves with an electric field in the BB' direction are polarized waves B.
If we consider the case where a linearly polarized electromagnetic wave having an electric field in a direction making a 45° angle with AA' and BB' is incident, this can be decomposed into polarized waves A and B, which have the same amplitude and phase. Because of the presence of the dielectric plate 2, the internal wavelength of the polarized wave A becomes shorter than the internal wavelength of the polarized wave B.

Therefore, a phase shift difference occurs between the polarized waves A and B at the output end. This phase shift difference is 90°, and polarization A and polarization B
When the amplitudes of the waves are equal, the waves are output as circularly polarized waves.

By the way, circularly polarized wave generators are generally constructed of only low-loss dielectrics or metal conductors in order to efficiently convert linearly polarized waves to circularly polarized waves.

It is better for the input reflection coefficient to be small for both polarization A and polarization B. 6 When both reflection coefficients are close to O, the magnitude of the transmission coefficient for both is close to 1. Then, the condition that the amplitudes of polarized waves A and B are equal is satisfied.

Therefore, the following three conditions must be satisfied for a circularly polarized wave generator.

(i) The reflection coefficient of polarized wave A is sufficiently small.

(ii) The reflection coefficient of polarized wave B is sufficiently small.

(iu) The phase shift difference between polarization A and polarization B is sufficiently close to 90°.

[Problems to be Solved by the Invention] A wide variety of circularly polarized wave generators have been developed in the past. For example, the one in which the dielectric plate 2 shown in FIG. 4 is inserted has a simple structure and is easy to manufacture. However, the shape of the tapered part 2' at the input and output ends of the dielectric plate 2 must be determined so as to satisfy the above conditions, which requires a long development period due to repeated trial experiments, and also It is difficult to obtain satisfactory characteristics just by devising the shape of 2'.

As another conventional example, as shown in FIG. 5, there is a type in which a metal plate 3 is inserted into the waveguide 1, but this also has problems not only with the shape of the taper part but also with the phase shift difference. Since it has the characteristic of decreasing as the frequency increases, broadband linear polarization and circular polarization conversion is rotation.

As another conventional example, as shown in Fig. 6, a conductor fin 4 is provided on a part of the tube wall and used as a circularly polarized wave generator with broadband characteristics or a circularly polarized wave generator that can share two frequency bands. However, some have complex shapes and can provide a wide band by arranging conductor rods 5 such as screws at specific intervals within the AA' plane. However, this conventional example is not suitable for mass production because the structure is complicated and the insertion length of each screw 5 must be adjusted to compensate for manufacturing variations.

Currently, circularly polarized wave generators are used, for example, in some home satellite broadcasting receiving antennas, and there is a need for something that is easy to manufacture, suitable for mass production, and has excellent characteristics. However, nothing that can meet these demands has yet been realized.

[Object of the Invention] Therefore, an object of the present invention is to provide a circularly polarized wave generator that has a simple structure, is suitable for mass production, and can be developed in a short period of time, in order to solve the drawbacks of the conventional example described above.

[Means for Solving the IK Problem] In order to achieve the above object, the present invention provides a method in which the negative polarization of two orthogonal polarizations in the waveguide is matched, and The gist is that two phase shifters are provided so that the phase difference between the two polarized waves is 45°, and the distance between the two phase shifters is set so that the other polarized wave can be matched.

[Operation] The above two phase shifters can satisfy the above condition (i) or the two conditions (it) and (fit) at the same time, and by appropriately adjusting the distance between both phase shifters, other conditions can be satisfied. It becomes possible to satisfy one of the conditions.

[Examples] The present invention will be described below with reference to examples shown in the drawings. FIGS. 1 and 2 show an embodiment of a circularly polarized wave generator according to the present invention, in which a dielectric plate having an approximately hexagonal shape is placed in a circular waveguide 1 on a plane including AA' and the tube axis. Two phase shifters of 6°6' are inserted at a predetermined distance d.

In the conventional single dielectric insertion type circularly polarized wave generator as shown in FIG. 4, a phase shifter ( dielectric plate)
It is difficult to find the shape of a part of the taper.

However, it is relatively easy to create a device that satisfies either one of the conditions (i) or (it) above and the condition (in) above regarding the phase shift difference.1For example, if the reflection coefficient of polarized wave B is Assume that the shape of the dielectric 6 that acts as a phase shifter such that the amount of phase shift between the polarized waves A and B is 45° is determined. When two of these dielectric plates are inserted in the plane that includes AA'' in the waveguide 1 and the tube axis as shown in FIG. It becomes a 90° phase shifter.At this time, the magnitude of the reflection of polarized wave A changes depending on the distance d between the two dielectric plates 6 and 6'.Therefore, the reflection of polarized wave A by dielectric plate 6 on the input side waves and
By adjusting the interval d so that the reflected waves of the polarized wave A by the dielectric plate 6' behind it cancel each other out, the reflection of the polarized wave A can also be made sufficiently small.

In this way, it is clear that the above-described embodiment satisfies all of the conditions (i), (ii), and (b) that a circularly polarized wave generator should satisfy.

Note that the dielectric plate used as a phase shifter with a small reflection of one polarized wave and a phase difference of 45° can have various shapes other than the hexagonal shape described above, and such dielectric plates A desired circularly polarized wave generator can be developed using a similar design method using not only an insertion type phase shifter but also other types of phase shifters.

Furthermore, according to the present invention, it is also possible to realize a circularly polarized wave generator that can be used in two frequency bands. For example, the frequency is from f□ to f
In order to perform linear polarization/circular polarization conversion in the low frequency band up to 2 and the high frequency band from f, to f, the following six conditions must be satisfied.

(1) The reflection coefficient of polarized wave A from fl to f□ is sufficiently small.

(2) The reflection coefficient of polarized wave B from f to f2 is sufficiently small.

(3) The phase difference between polarization A and polarization 8 from f to f2 is sufficiently close to 90''.

(4) The reflection coefficient of polarized wave A from fl to f4 is sufficiently small.

(5) The reflection coefficient of polarized wave B from fl to f4 is sufficiently small.

(6) The phase shift difference between polarization A and polarization 8 from fl to f4 is sufficiently close to 90'.

It is very difficult to satisfy these six conditions at the same time. However, it is very difficult to create a phase shifter that satisfies any two of conditions 1), (2), (4), and (5) and conditions (3) and (6) regarding the phase shift difference. - As an example, the phase shifter having conductor fins 4 shown in FIG. 6 will be used for explanation, but it is of course possible to design the phase shifter in the same way using other types of phase shifters. be.

FIG. 3 shows another embodiment of the invention designed in the manner described above, in which numerals 7 to 10 represent phase shifters of the type shown in FIG.
It is assumed that the phase shift difference is 22.5° in the two frequency bands from l to f2 and from fl to f4, and the conditions (2) and (5) above are satisfied.

First, two phase shifters 7 and 8 are used, and the interval d□ between them is adjusted to satisfy the condition (1). As a result, the phase shifters 7 and 8 have a phase shift difference of 45° in the two frequency bands from fl to f2 and from fl to f4, and (1), (2
) and (5) will be satisfied.

Furthermore, if the interval between the other two phase shifters 9 and 10 is also d□,
These phase shifters 9 and 10 are the same as phase shifters 7 and 8. Then, adjust the distance d2 between the phase shifters 8 and 9 to obtain the above (4).
Ensure that the conditions are met.

Thus, the phase shifters 7 to 10 simultaneously satisfy all of the conditions (1) to (6) above.

[Effects of the Invention] As explained above, according to the present invention, the circularly polarized wave generator has an extremely simple structure using only two phase shifters and has excellent characteristics, so it is easy to manufacture and suitable for mass production. , the practical effects are great.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing one embodiment of the present invention, FIG. 2 is a sectional view thereof, FIG. 3 is a sectional view showing another embodiment of the present invention, and FIGS. 4 to 7 are respectively conventional FIG. 2 is a perspective view showing a circularly polarized wave generator. 1... Waveguide, 2, 2'...
...Dielectric plate, 4... Conductor fin, 5.
・・・・・・・・・Conductor rod, 6,6'・・・・・・・・・
Dielectric plate, 7 to 10... Phase shifter. Patent Applicant Kyocera Corporation Agent Patent Attorney Nagai 1) Takeshi Part 3 Figure 2 Figure 4 Figure 5 Figure 6 Figure 7

Claims (1)

[Claims] Two phase shifters are arranged in the waveguide so that one of the two orthogonal polarized waves in the waveguide is matched and the phase difference between the two polarized waves is 45°. 1. A circularly polarized wave generator, characterized in that the distance between both phase shifters is set so that the other polarized wave can be matched.