JPH03236602A - Circularly polarized wave/linearly polarized wave converter - Google Patents

Abstract

PURPOSE:To eliminate a step difference at an end face of a phase circuit so as to reduce the production of a harmonic mode wave, to eliminate a structure for the phase circuit provided in the inside of a waveguide and to reduce the working man- hour by employing ellipse structure for the phase circuit of the waveguide and changing the shape of the structure gradually from the elliptic shape into the circular shape. CONSTITUTION:A waveguide 14 forming one end as an ellipse 9 and the other end as a circle 10 is employed, and when an electromagnetic wave is made incident a or face of the ellipse 9, since the width in the Y axis direction is made narrow, it is possible to decrease a guide wavelength of the electric field component Y more than the guide wavelength of the electric field component X. Since the frequency is unchanged, the action of causing a delay in the phase speed of the electric field component Y is gradually decreased by selecting the lengthwise side of the waveguide 14 so that the phase speed in the waveguide of the electric field component Y is retarded by 90 deg. from that of the electric field component X. Thus, a circularly polarized wave is converted into a linearly polarized wave at a position where the wave passes through the elliptic waveguide 14.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a circular polarization/linear polarization converter, and in particular to a circular polarization converter for electromagnetic waves used to reduce interference between two satellite broadcasting systems. This invention relates to a circular polarization/linear polarization converter used on the reception side and the transmission side for polarization. Here, the circularly polarized wave/linearly polarized wave converter includes a linearly polarized wave to circularly polarized wave converter and a circularly polarized wave to linearly polarized wave converter.

Broadcasting satellites in Japan emit right-handed circularly polarized electromagnetic waves as broadcast signals, and in order to create right-handed circularly polarized waves, a circular polarization converter is used to convert the linearly polarized waves into circularly polarized waves at the power feeding section of the antenna of the equipment onboard the satellite. A polarization generator is used.In addition, right-handed circularly polarized electromagnetic waves from a broadcasting satellite are received by a reflector of a ground-based receiving BS antenna, as shown in Figure 4, and the electromagnetic waves reflected by the reflector are transferred to a reflector. The 1M wave is incident on the aperture of the primary radiator installed at the focal point of the primary radiator, and is further incident on the structural part that converts the circularly polarized wave into linearly polarized wave. The signal is converted into a linearly polarized wave and sent to the BS converter, where it is converted into an electrical signal and signal processing is performed.

In principle, the linear polarization/circular polarization converter used in satellite equipment and the circular polarization/linear polarization converter used in ground receiving equipment are based on the same principle. can.

[Conventional technology]

FIG. 5 shows a conceptual diagram of a circularly polarized wave/linear polarized wave converter used in conventional terrestrial receiving equipment, viewed from the side. The primary radiator has a horn-shaped shape to efficiently collect the electromagnetic waves reflected by the reflector of the BS antenna and guide them to the waveguide. Part A of the waveguide receives the broadcast waves generated in part B. It is a circular waveguide section provided to attenuate higher-order modes other than the fundamental mode of electromagnetic waves necessary for The input circularly polarized electromagnetic wave is converted into a linearly polarized wave in the phase circuit structure that converts the circularly polarized wave/linearly polarized wave. guided by the parts. Section C is a circular waveguide section, which is provided to attenuate higher-order modes generated at the junction between the phase circuit structure section and the circular waveguide section. Part D shows the impedance between the waveguide and the excitation probe, which is used to efficiently extract signals to the outside of the waveguide by coupling the linearly polarized electromagnetic waves using an excitation probe made of metal poles. This is the part that performs matching, and the signal extracted by the excitation probe is input to the low-noise amplifier of the BS converter for signal processing. As a coupling means, in addition to the above-mentioned excitation probe, a method using a rectangular waveguide is also used.

Circularly polarized waves are two orthogonal linearly polarized waves whose amplitudes and frequencies are equal and whose phases are shifted by 90 degrees, and if a phase circuit is installed to make the phases of both linearly polarized waves the same, a linearly polarized signal is obtained. However, examples of the phase circuit structure used conventionally for converting circularly polarized waves/linearly polarized waves are shown in FIGS. 6(a), (b) to 9(a).
), (b) are shown. Figure (a) is a front view seen from the opening of the waveguide, and figure (b) shows an individual view of the phase circuit portion of the waveguide.

FIG. 6 shows a dielectric plate 2 that is tilted at 45 degrees to the direction of the linearly polarized wave extracted as a signal by the coupling means and parallel to the vertical electric field component Y of one of the two linearly polarized waves orthogonal to each other. is attached inside the waveguide l. By attaching the dielectric plate 2 inside the waveguide 1 in this way, the phase of the linearly polarized wave of the electric field component parallel to the dielectric plate 2 can be delayed, and therefore the phase of the linearly polarized wave of the other horizontal direction of the linearly polarized wave can be delayed. If the dimensions of the dielectric plate 2 in the longitudinal direction are selected to such a length that the component Y lags the electric field component Become. In addition to this, the following are used as examples of phase circuit structures with such an effect. Figure 7(a) and (
(b) As a phase circuit structure, two metal plates 4 are attached to the centers of opposing circular arcs on the inner surface of the waveguide 1, with the short sides of each metal plate 4 facing toward the center of the waveguide 1. So,
Furthermore, a metal plate 4 is attached to extend in the longitudinal direction of the waveguide 1.

In addition, FIG. 8 shows that two metal lumps 5 are attached to the inner surface of the waveguide 1 by extending them in the longitudinal direction of the waveguide so that the two opposing circular arcs on the inner surface of the waveguide become flat. If the vertical electric field component of two orthogonal linearly polarized waves is Y, and the horizontal electric field component is X, then the metal block is By adding 5, the tube wavelength of electric field component Y can be structurally made shorter than the tube wavelength of electric field component If the dimensions of the metal block 5 in the longitudinal direction are selected to such a length that the phase of the component Y is delayed by 90 degrees, the circularly polarized wave will be converted into a linearly polarized wave at the position where it passes through the metal block 5. In addition to this, the following are used as examples of phase circuit structures with such an effect. Figures 9(a) and (
In b), the waveguide is deformed so that the cross section seen from the opening of the waveguide 7 is elliptical.

Sixth, when a phase circuit as shown in Fig. 7 or Fig. 8 is provided in the B section inside the waveguide as shown in Fig. 5, or an elliptical waveguide is installed as a phase circuit as shown in Fig. 9. When connecting with a circular waveguide with a step, the electric field distribution of electromagnetic waves will change due to structural changes inside the waveguide at the interface between circular waveguides A and C and the phase circuit. As a result, higher-order modes other than the fundamental mode of electromagnetic waves necessary for receiving broadcast waves are generated at the boundary surface, which may disturb the radiation characteristics of the primary radiator or reduce the degree of coupling between the linearly polarized signal and the excitation probe. or lower it.

[Problem to be solved by the invention]

Therefore, when a phase circuit as shown in FIG. 6, FIG. 7, or FIG. In the examples shown in FIGS. 7 and 8, the portions are recessed, and in the examples shown in FIGS. 7 and 8, steps are provided to attenuate the generation of higher-order modes. By eliminating the step in the
In the conventional example, a phase circuit was provided inside the waveguide, which resulted in a complicated structure and required a large number of processing steps.

The present invention aims to further reduce the occurrence of higher-order modes and reduce the number of processing steps.

[Means to solve the problem]

As shown in Fig. 1(a), (b) and Fig. 2(a), (c), the primary radiator 8 has a horn-shaped shape, and the surface of the primary radiator 8 with a small opening A waveguide 14 which is gradually deformed from an elliptical shape 9 to a circular shape 10, with an aperture surface of one joined end having a substantially elliptical shape 9 and an aperture surface of the other end a circular shape 10;
A circular waveguide 15 is provided with a coupling means using an excitation probe 13 for coupling a linearly polarized wave signal in the middle between the circular apertures 10 of 4 and the apertures are joined to each other. The longitudinal length of the waveguide 14 converts between circularly polarized waves and linearly polarized waves, and the excitation probe 13 transmits signals between the electromagnetic waves inside the tube and the external circuit of the waveguide.

[Effect]

In the present invention, FIGS. 1(a), (b) and 2(a),
As shown in FIG. 1(b), a waveguide 14 with an elliptical shape 9 at one end and a circular shape 10 at the other end is used, and when an electromagnetic wave is incident on the elliptical surface 9, it is vertical in FIG. 1(a). If the direction is the Y-axis and the horizontal direction is the
The wavelength within the tube can be made shorter than the wavelength within the tube of electric field component If the longitudinal dimension of the elliptical waveguide 14 is selected, the structure of the phase circuit gradually changes from an ellipse to a circle as shown in the cross section in Fig. 3, which causes a delay in the phase velocity of the electric field component Y. Although the effect gradually decreases, at the position where the electromagnetic wave passes through the elliptical waveguide 14, the circularly polarized wave is converted into a linearly polarized wave.

〔Example〕

Figures 1(a) and 2(a) to 2(b) show a circularly polarized wave/linearly polarized wave converter showing an embodiment of the present invention,
(a) is a front view of the circularly polarized wave/linearly polarized wave converter seen from the aperture of the primary radiator, (b) is a circularly polarized/linearly polarized wave obtained by cutting the above figure (a) along the line l-l. A cross-sectional view of the side of a linear polarization converter,
FIGS. 2(a) and 2(b) show the circularly polarized wave/linearly polarized wave converter rotated 90 degrees counterclockwise from the positions shown in FIGS. 1(a) and (b).

The smaller surface of the aperture of the primary radiator 8 which is shaped like a horn, and the ellipse that gradually transforms from the ellipse 9 to a circle 10, with the aperture surface at one end being an ellipse 9 and the aperture surface at the other end being a circle 10. The elliptical aperture surface of the waveguide 14 is joined to the circular aperture surface of the waveguide 14, and coupling means using an excitation probe 13 for coupling the linearly polarized signal is provided in the middle. The opening surfaces of circular waveguides 15 with terminals 12 are joined to each other, and the longitudinal length of the waveguide 14 converts between circularly polarized waves and linearly polarized waves, and the excitation probe 13 converts the inside of the tube. The linearly polarized signal is transmitted between the waveguide and the external circuit.

In FIG. 1(a), if the vertical direction is the Y axis and the horizontal direction is the X axis, the long axis of the ellipse 9 of the elliptical waveguide is located on the X axis, and the excitation probe 13 is the excitation probe The waveguide 15 is attached to the wall surface of the circular waveguide 15 such that the extension line of the center of the waveguide 13 and the X axis form an angle of 45 degrees.

In Fig. 1 Φ), the excitation probe 1 of the circular waveguide 15
3, the mounting position between the phase circuit structure part and the circular waveguide is adjusted by adjusting the mounting path gIC between the opening of the circular waveguide 15 and the excitation probe 13 so that the maximum excitation signal is obtained at the excitation probe 13. 15, and by adjusting the distance HD, the impedance of the mounting portion of the excitation probe 13 is matched to the linearly polarized signal reflected at the termination surface.

The joining part between the primary radiator 8 and the elliptical waveguide 14 is a part that matches a circle whose diameter is the long axis of the ellipse of the elliptical waveguide 14 to be joined, and the primary radiator 8 has a horn shape. and an elliptical waveguide 14, the major axis of the ellipse is in direct contact with the horn-shaped slope, and the minor axis of the ellipse is a circle whose diameter is the major axis of the ellipse. A vertical surface 11 is provided up to the outer circumferential portion of the ellipse to join the horn-shaped inclined surface and the shorter diameter portion of the ellipse.

Alternatively, the vertical surface 11 may be sloped so that the horn-shaped slope and the short diameter portion of the ellipse are joined by a gentle slope.

FIG. 3 is a cross-sectional view of the elliptical waveguide, and as shown in FIG. -2. 3(a) and 3(b) show a cross section cut along line 131 and a cross section cut along line 131, respectively.

Shown in (C). In the figure, 16 is the cut surface of the side wall of the elliptical waveguide, and the opening surface of the elliptical waveguide gradually changes from an ellipse to a circle, and the major axis of the ellipse 9 is from (a) to (b). The length becomes shorter as the figure goes, and the cut plane is circular 10 in figure (C).

The above is an example in which a circularly polarized wave/linearly polarized wave converter is used on the receiving side, but the structure according to the present invention may be used as a circularly polarized wave generator, for example, in Fig. 1 0)). , the excitation probe 1 transmits a signal from an external circuit using the excitation probe 13 to excite electromagnetic waves inside the waveguide.
B generates linearly polarized waves at position 3 and has a phase circuit structure.
Linearly polarized waves can be converted to circularly polarized waves depending on the length of the section,
It is also possible to radiate circularly polarized waves from the -order radiator 8.

For example, in FIG. 1(a), the mounting position of the excitation probe 13 is moved clockwise, and the mounting position of the excitation probe 13 before movement, the center point of the waveguide, and the mounting position of the excitation probe 13 after movement are compared. If the moving angle of the position is set to 90 degrees, it can also be used as a counter-rotating circularly polarized wave/linear polarized wave converter.

In the above embodiment, the excitation probe 13 is used as the coupling means, but a rectangular waveguide may be used to transmit the linearly polarized wave signal inside the tube and the signal between the external circuit of the waveguide. .

〔Effect of the invention〕

As explained above, according to the present invention, an elliptical structure is used as a phase circuit of a waveguide, and by gradually changing from an ellipse to a circular shape, the step at the end face of the phase circuit is eliminated and high-order The generation of modes is reduced compared to the conventional example, and
By eliminating the phase circuit structure provided inside the waveguide, it is possible to reduce the number of processing steps and provide a circularly polarized wave/linearly polarized wave converter with low manufacturing cost.

[Brief explanation of drawings]

1(a), (b) to FIG. 2(a), (b) show a circularly polarized wave/linearly polarized wave converter showing one embodiment of the present invention, in which (a) is - A front view of the circularly polarized wave/linearly polarized wave converter seen from the aperture surface of the radiator, (b) is a sectional view of the side surface of the circularly polarized wave/linearly polarized wave converter, Figures 2(a), ( b) is shown in Figure 1 (a)
). Figure 3 is a cross-sectional view of the elliptical waveguide, and Figure 4 is a schematic diagram of the receiving BS antenna. A side view, Fig. 5 is a conceptual diagram of a circularly polarized wave/linear polarized wave converter showing a conventional example, and Figs. 6 (a), (b) to 9 (a), (b) show conventional examples. It is a phase circuit structure diagram. 1, 15---One circular waveguide, 2- Dielectric plate, 4---Metal plate, 5- Metal lump, 7. 14-
Elliptical waveguide, 8...-primary radiator, 9... ellipse, 10--circular, 11--111 vertical plane, 1
2...Terminal surface, 13--Excitation probe, 16-
−・−・Cut surface of side wall.

Claims (1)

[Claims] A horn-shaped primary radiator is connected to a smaller aperture of the same primary radiator, with the aperture at one end shaped like an ellipse and the aperture at the other end circular, gradually transforming the oval into a circle. 1st
It consists of a waveguide and a circular second waveguide having a circular opening surface of the first waveguide and a coupling means for coupling the linearly polarized signal in the middle where the opening surfaces are joined and the end thereof is terminated. , a circularly polarized wave/linearly polarized wave converter, characterized in that conversion between circularly polarized wave and linearly polarized wave is performed by the length of the first waveguide in the longitudinal direction.