JPS5928081B2 - circular polarization generator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a microwave band circularly polarized wave generator that improves the deterioration of characteristics caused by the resonance phenomenon of higher-order mode waves.

Figure 1 is a perspective view showing an example of a conventional circularly polarized wave generator.
2 is a circular waveguide with a partially deformed inner wall; 2 is a dielectric plate provided inside the deformed circular waveguide 1 in the tube axis direction; 3a;
, 3b and 3c are conductor wires AA elongated in the direction of the tube axis, which are provided close to each other on the straight line A parallel to the tube axis on the dielectric plate 2, respectively.

AB, AC, 4a, 4b, and 4c are conductor wires BA elongated in the tube axis direction, which are provided close to each other on a straight line B parallel to the tube axis on the dielectric plate 2, respectively.

BB, BC, and 5a, 5b, and 5° are conductor wires CA, which are elongated in the tube axis direction and are provided close to each other on a straight line C parallel to the tube axis on the dielectric plate 2, respectively.

CB and CC, and each conductor wire is arranged so that three conductor wire ends are aligned in one plane perpendicular to the tube axis.

First, the operating principle of a circularly polarized wave generator using a dielectric plate as one of the phase elements will be explained below.

In FIG. 1, a dielectric plate 2 is inserted in a plane (hereinafter referred to as the Y1-Y2 plane) that includes the Y1-Y2 axis and the tube axis.

Here, a wave whose electric field is parallel to the Yl-Y2 plane is polarized by Y1-Y
A polarized wave X is a wave whose electric field is parallel to a plane (hereinafter referred to as the X1-X2 plane) including the X1-X2 axis and the tube axis, which are orthogonal to the two axes.

The polarized waves Y and X are the TEL and mode waves of the fundamental mode waves of the deformed circular waveguide 10 that are orthogonal to each other, respectively.

Since the electric field is parallel to the dielectric plate 2, the polarized wave Y is affected by the dielectric plate 2, but is hardly affected by the deformation of the deformed circular waveguide 1.

Since the electric field is orthogonal to the dielectric plate 2, the polarized wave X is hardly affected by the dielectric plate 2, and is only affected by the deformation of the deformed circular waveguide 1.

Here, in order to simplify the explanation, two frequency bands will be considered and a case of a circularly polarized wave generator that can be used for both bands will be explained.

Note that the lower limit frequency of the lower frequency band of the two frequency bands is fLl, the upper limit frequency is fL2, the lower limit frequency of the higher frequency band is fHll, and the upper limit frequency is fH2.

In addition, in order to obtain a good elliptical polarization factor and to use as wide a frequency bandwidth as possible, fL2 and fH
2 is selected to have a frequency slightly lower than the cutoff layer wave number of the TMol and TM11 mode waves in the circular waveguide having the same inner diameter as the deformed circular waveguide 1, respectively.

A desired circularly polarized wave generator can be obtained by determining the length of t so that the frequencies fL1 to fL2 and fHl hold.

Here, λgY is the internal wavelength of the polarized wave Y, λgY is the internal wavelength of the polarized wave X, and t is the length of the dielectric plate 2.

However, in the polarized wave Y of the circularly polarized wave generator equipped with the dielectric plate 2, the cut-off frequency for fundamental mode waves and higher-order mode waves is that of a circular waveguide with the same inner diameter as the deformed circular waveguide 1. It is lower than the cutoff frequency for fundamental mode waves and higher order mode waves.

Therefore, the cutoff frequencies of TMol and TMl in the polarized wave Y of the circularly polarized wave generator and the mode waves are lower than fL2 and fH2, respectively.

In the circularly polarized wave generator, the TMo1 mode wave is generated in the frequency band between the cutoff frequency of the TMo1 mode wave and fL2 and TM
, the 1 mode wave is the cutoff frequency of the TM11 mode wave and fH
When generated in the frequency band between 2 and 2, this TMol and TMl mode wave is generated because a circular waveguide with the same inner diameter as the deformed circular waveguide 1 is connected to both ends of the circularly polarized wave generator. It is reflected by the circular waveguides at both ends, and the tube axis length of the circularly polarized wave generator is TMol and TMl, which is 2 times the tube wavelength of the mo wave.
A resonance phenomenon occurs at a frequency that is an integral multiple of 1/2, degrading the characteristics of the circularly polarized wave generator.

Therefore, in the conventional circularly polarized wave generator, the dielectric plate 2
A thin conductor wire is provided in the tube axis direction, and the TMo.

and TMl, the shape is such that the mote family cannot propagate.

Since this conductor wire has a long shape in the tube axis direction, it hardly affects the TE11 mode wave which has an electric field component only in a plane perpendicular to the propagation axis.

Therefore, polarization Y and polarization X due to the provision of conductor wires
The effect on the phase difference between the two is small.

On the other hand, TMol and TMl mode waves have electric field components in the tube axis direction.

Therefore, if the conductor wire is provided in the tube axis direction at a position where the electric field component in the tube axis direction is strong, the TMol and TM1□ mode waves cannot propagate.

However, if a conductor wire is provided on the dielectric plate 2, the TEM mode wave can propagate using the conductor wire as a center conductor.

TEM mode waves are likely to be excited if the structure in the cross section perpendicular to the tube axis of the circularly polarized wave generator is not symmetrical with respect to the tube axis.

The electric field distribution of this TEM mode wave is very similar to the electric field distribution of the TMo1 mode wave, and mode conversion occurs between the TEM mode wave and the TMo mode wave.

For example, a part of a TEM mode wave propagating through a conductor wire as a center conductor is converted into a TMo1 mode wave at the end of the conductor wire, and the remaining energy is reflected.

Therefore, when a TEM mode wave is excited, some of it is TM
The o1 mode wave propagates through the waveguide, and the remaining TEM mode wave is confined in the conductor line section.

If a large amount of TEM mode waves are generated, it leads to generation of TMo1 mode waves and deterioration of characteristics of the circularly polarized wave generator, such as a confined resonance phenomenon.

Therefore, in order to reduce the amount of TEM mode waves generated, the length of the conductor wire is set to 2 times the free space wavelength in the two frequency bands.
It is chosen so that it is not an integral multiple of 1/1.

However, this conventional circularly polarized wave generator has the following drawbacks.

First, the arrangement of conductor wires will be explained.

When conductor wires are placed close to each other on straight lines A, B, and C parallel to the tube axis, there is a A potential difference occurs.

Therefore, the electrical characteristics between each conducting wire exhibit capacitive susceptance.

Here, for convenience of explanation, conductor wire AA3a and conductor wire ABa
The capacitive susceptance between conductor line CA5a and conductor line CBSb is assumed to be CA1 and Ccl, respectively.

Conductor wire AA3a, conductor wire CA5a1, and conductor wire AB3
If the symmetry of the positions of the conductor line CB5b and the conductor line CB5b with respect to the Xl-X2 plane is excellent, then CA1 is Cc1.

However, if the symmetry is poor, CAIXCcl occurs, resulting in unbalanced electrical characteristics between the conductor wire AA3a and the conductor wire -ABab and between the conductor wire CA5a and the conductor wire CBSb, and TMo and TEM mode waves are generated.

For this reason, in conventional circularly polarized wave generators, the length of the conductor wire is
Even if the frequency band is selected so that it is not an integer multiple of 1/2 of the free space wavelength, the T
When EM mode waves or TMo1 mode waves occur, the conductor wire is effective for TM mode waves but not for TMo1 mode waves, and resonance phenomena are likely to occur and higher order mode waves are likely to occur. There was a drawback.

This invention aims to eliminate the above-mentioned drawbacks and to obtain a circularly polarized wave generator with less deterioration of characteristics due to resonance phenomenon. The conductor wires are arranged apart from each other in the tube axis direction so that the gaps between the conductor wires on three straight lines do not approach the gaps between the conductor wires on adjacent straight lines.

As clarified in the explanation of conventional circularly polarized wave generators, if the symmetry of the conductor line position is poor, a resonance phenomenon occurs that reduces the effect on the capacitive susceptance of the conductor line, resulting in less deterioration of characteristics. A polarization generator can be obtained.

Hereinafter, one implementation of this invention will be explained with reference to FIG.

In Figure 2, the same symbols or symbols as in Figure 1 indicate the same content or corresponding parts, 6a, 6b, 6
c and 6d are elongated conductor wires DA, DB, DC, and D arranged parallel to the tube axis on the dielectric plate 2 and spaced apart from each other in the tube axis direction so as not to approach each other in a straight line.
D, 7a, 7b.

7c and 7d are conductor wires EA, EB, EC, and ED elongated in the tube axis direction, which are provided close to each other on a straight line E parallel to the tube axis on the dielectric plate 2, and 8a, 8b, and 8c
and 8d are conductor wires FA, FB, and FC that are elongated in the tube axis direction and are provided close to each other on a straight line F parallel to the tube axis on the dielectric plate 2.

The conductor wires are arranged so that the gaps between the conductor wires on each straight line do not come close to the gaps between the conductor wires on adjacent straight lines.

Here, the capacitive susceptances between conductor wire DA6a and conductor wire DBGb and between conductor wire FA8a and conductor wire FBBb are assumed to be CD1 and CFL, respectively.

In this case, since the conductor wire EB7b is arranged near the gap between the conductor wire DA6a and the conductor wire DB6b and the gap between the conductor wire FA8a and the conductor wire FBBb, the CD1
and CFt is the CA used to explain the conventional circularly polarized wave generator.
CD1<CA1 and CFI for t and Ccl
The relationship of <CBt is shown.

This is because the potential difference caused by the microwave generated between the conductor wire DA6a and the conductor wire DBGb and between the conductor wire FA8a and the conductor wire FBBb hardly occurs because the circuit is short-circuited with equal constraints by the conductor wire EB7b.

From now on, it will become CD1zO9CF1zO.

For this reason, the symmetry of the conductor wire DA6a and conductor wire DB6b, and the conductor wire FA8a and conductor wire FB8b positions with respect to the The drowsy imbalance that occurs between FA8a and conductor wire FBab is small.

In other words, the amount of TMol and TFM mode waves generated due to this electrical imbalance is clearly smaller than before, and therefore, the energy when these mode waves cause a resonance phenomenon is also naturally lower. However, it is smaller than before.

Therefore, even when the symmetry of the conductor lines is poor, a circularly polarized wave generator can be obtained in which electrical characteristics are less likely to deteriorate due to resonance phenomena.

Note that although the case of a circularly polarized wave generator having a structure in which a dielectric plate 2 is provided on a deformed circular waveguide 1 has been described above, the present invention is not limited to this. The present invention may be used in a circularly polarized wave generator made up of a phase-adjusted waveguide and a dielectric plate.

Although we have described the case where four conductor wires are arranged on one side of the dielectric plate 2 in the tube axis direction, they may be provided on both sides of the dielectric plate 2, and the number of conductor wires does not need to be four to be arranged in the tube axis direction. good.

As described above, in the circularly polarized wave generator according to the present invention, a plurality of conductor wires long in the tube axis direction are arranged on the dielectric plate in three directions parallel to the tube axis.
The resonance phenomenon can be prevented by placing the conductor wires close to each other on each straight line of the tree and arranging them so that the gaps between the conductor wires on each straight line do not approach the gaps between the conductor lines on the adjacent straight lines. This has the effect of making it possible to obtain a circularly polarized wave generator whose characteristics are less likely to deteriorate due to this phenomenon.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway perspective view of a conventional circularly polarized wave generator, and FIG. 2 is a partially cutaway perspective view of a circularly polarized wave generator showing an embodiment of the present invention. In the figure, 1 is a deformed circular waveguide, 2 is a dielectric plate, 3a, 3
b. 3o, 4a, 4b, 4o, 5a, 5b, 5c, 6a. 6b, 6c, 6d, 7a, 7b, 7c, 7d, 8a. 8b, 8o and 8d are conductor wires AA, respectively. Conductor wire AB, conductor wire AC, conductor wire BA, conductor wire BB, conductor wire BC, conductor wire CA, conductor wire CB, conductor wire CC1 conductor wire DA, conductor wire DB, conductor wire DC. These are conductor wire DD, conductor wire EA, conductor wire EB, conductor wire EC, conductor wire ED, conductor wire FA1, conductor wire FB, conductor wire FC, and conductor wire FD. It should be noted that the same or equivalent parts in the figures are indicated by the same reference numerals.

Claims (1)

[Claims] 1. In a microwave band circularly polarized wave generator using a dielectric plate as one of the phase elements, there is a circularly polarized wave generator on the dielectric plate which is elongated in the direction of the tube axis and whose length is two times the free space wavelength within the used frequency band. A plurality of conductor wires whose length is not an integral multiple of 1/2 are provided close to each other on three straight lines parallel to the tube axis, and furthermore, between the conductor wires on each straight line, A circularly polarized wave generator characterized in that the gaps are spaced apart from each other in the tube axis direction so as not to approach the gaps between the conductor wires on adjacent straight lines.