JPS58203B2 - Kousahenpakairiyo Antenna Souch - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a rosy system for asymmetry and cross-polarization characteristics in an antenna that is asymmetric in principle, such as a general horn reflector antenna.

The conventional characteristics of the conical horn reflector antenna will be described below.

FIG. 1 is a schematic diagram of a horn reflector antenna, which is conventionally known as an asymmetric antenna.

In the figure, reference numeral 1 denotes a spray horn, such as a conical horn or a corrugated conical horn.

Reference numeral 2 denotes a wavefront converter, which is, for example, a parabolic mirror or an elliptical mirror.

FIG. 2 is an explanatory diagram of asymmetry and cross-polarized wave generation using a conical horn reflector antenna as an example.

In the figure, 3 is a conical horn reflector antenna, 4 and 5 are coordinate axes with the origin at the center of the antenna aperture,
The X and Y axes are shown, respectively.

Note that here, the direction perpendicular to the surface of the paper toward the front is defined as the Z axis.

6 shows the electric field distribution at the antenna aperture when the antenna is excited in the form of a circular waveguide TE11 having an incident polarization plane in the X-axis direction.

7゜8.9 and 10 are components of the electric field distribution 6, where 7 is the first-order component of the main polarization component in the circumferential direction, 8 is the second-order component of the main polarization component, and 9 is the cross-polarization component. , and 10 is the fourth-order component of cross polarization.

The electric field distribution 6 is approximately represented by the superposition of these four components.

Therefore, the radiation pattern of the main polarization has asymmetry in the X-Z plane due to the second-order component shown in 8, and the radiation pattern of cross-polarization has the second-order component shown in 9 and the radiation pattern shown in 10. Determined by the fourth order component.

Figures 3 and 4 show these typical three-dimensional radiation patterns.

Here, Figure 3 shows a blowing horn (for example, a conical horn reflector antenna with a small opening angle using a conical horn).
(shown in Figure 1).

This shows a three-dimensional radiation pattern when the polarization indicated by 10 in FIG. 2 occupies the main element of cross-polarized waves.

In addition, Fig. 4 shows the component indicated by 9 in Fig. 2, which is determined by a wavefront converter (shown in Fig. 1), such as a conical horn reflector antenna using a blowing horn that emits a rotationally symmetrical beam, such as a corrugated conical horn. The figure shows a three-dimensional radiation pattern when the main component of cross-polarized waves is

The purpose of this study is to propose a new technique to counteract the cross-polarization and asymmetry that occur in wavefront converters.

The principle of the present invention will be explained below using FIGS. 5 to 7.

Figure 5 is an electric field distribution diagram for the TE11 state of the circular waveguide, Figure 6
The figure shows an electric field distribution diagram in the TE21 state.

FIG. 7 shows an equivalent circuit for a horn reflector antenna.

In FIG. 7, 11 is an incident wave a1 on the TE11 attitude input side.
12 is a terminal for TEL, the reflected wave b1 on the attitude input side, 13 is a terminal for the incident wave a2 on the attitude output side of TE11, 1
4 is a terminal for TE11 state output side reflected wave b2, 15 is T
E2. Terminal 16 for the attitude input side incident wave a3 is TE2.
A terminal for the attitude input reflected wave b3, 17 a terminal for the TE21 attitude output side incident wave a4, and 18 a terminal for the TE21 attitude output side reflected wave b4.

19 is a wavefront converter. Of the four components 7, 8, 9, and 10 shown in the second diagram, by superimposing the components 7 and 10, the TE11 form of the circular waveguide as shown in the fifth diagram is obtained, and the components 8 and 9 are superimposed. This results in a TE21 configuration of a circular waveguide as shown in FIG.

Therefore, the conical horn reflector antenna can be used as a TE11
If the antenna is excited in the vertical position, the antenna aperture will mainly contain a mixture of the TEL and TE2 positions.

Since the TE21 configuration is a superposition of the asymmetry of the 8th component and the cross-polarization of the 9th component, by controlling this configuration, a conical horn reflector antenna with improved asymmetry and cross-polarization characteristics can be created. can be realized.

Since the conical horn reflector antenna can be treated as a reversible TE21 state converter, if it is excited in the TE21 state, contrary to the above, a TE21 state and a TE,1 state will occur.

The equivalent circuit of this antenna is shown in FIG. 7 above.

By replacing the wavefront converter 19 in FIG. 7 with an S matrix, the incident wave a1. a2. a3 and a4
And the reflected waves.

b2. The relationship between b3 and b4 is shown by the following equation.

If the conversion coefficient S12 from the TEH state to the TE21 state is β, S21 is also β due to reciprocity), a2 = a4 = b1
=b3-0, then equation (1) becomes.

Here, 1α12+1β12=1. αβ=β1α.

However, the * mark indicates a conjugate complex number.

Now enter the TE11 posture as 1. TE21 posture input a3
If Aejφ is Aejφ, and β is βoejφO, the conversion coefficient 1β1 is generally sufficiently smaller than 1, and can be set as 1−βo2:1.

The conditions for b4=0, that is, the transmitted wave in the TE21 state to be zero, are as follows from equation (4): βo=A (5) φ=(2m+1)π (6).

Specifically, in the case of an asymmetric antenna such as a conical horn reflector, this condition is such that the conical horn generates the required TE21 configuration and the phase of that configuration at the wavefront converter is made to be the same as that of the basic configuration TE11 configuration. It has been shown that the asymmetric cross-polarized waves generated in the wavefront converter can be eliminated by making the phase opposite.

Taking the conical horn reflector antenna as an example, we have analyzed it in the form of a circular waveguide, but in the case of a pyramidal horn reflector antenna, it can be handled with a rectangular waveguide, and in this case, the TE11 form of the rectangular waveguide can be controlled. Asymmetry and cross-polarization characteristics can be improved.

Since this principle can be easily understood from the above equation, it will be omitted here.

Furthermore, the Cass Horn antenna (Ca5-ho
rn Antenna), bent horn reflex antenna,
The asymmetric and cross-polarization characteristics of reflective beam-fed antennas and the like are also improved by the present invention.

Next, one embodiment of the present invention will be described using FIG. 8 and FIG. 9.

FIG. 8 is a schematic diagram of an embodiment of the present invention.

In the figure, 20 is a TE21 attitude generator, 21 is a phase compensator, 22 is a blowing horn, 23 is a wavefront converter, and 2
4 is a power feeding input terminal, and 25 is an antenna aperture.

An example of the TE21 attitude generator 20 described above is shown in FIG.

FIG. 9 shows the specific structure of the porous TE21 shape generator, in which there are a total of eight circular waveguides 26 and auxiliary waveguides 27.

Reference numeral 28 indicates small holes in the circumferential direction, and reference numeral 29 indicates the angle at which the sub-waveguides are attached, and they are attached at intervals of 45°.

When the power supply input terminal 24 is excited in the circular waveguide TE11 state, this wave is generated by the state generator 20 to generate the required TE21 state and T.
Converted to E11 posture.

This converted wave is given a required phase difference in a phase compensator 21 and sent to a blowing horn 22 .

The waves in both configurations emitted from the blowing horn 22 are wavefront converted by the wavefront converter 23. At this time, the TE2 configuration cancels out the TE21 configuration generated by the configuration generator 20, and the TE11 configuration is generated at the antenna aperture 25. Only transmits.

The same effect can be obtained even if this TE21 state wave is externally input to the spray horn 22 at an arbitrary phase.

Therefore, the attitude generator 20 and the phase compensator 21 are not necessarily required.

As described above, the present invention improves the asymmetry and cross-polarization characteristics of an asymmetric antenna such as a general horn reflector antenna by using a specific higher-order configuration of the waveguide configuration maintained in the horn ( For example, it can be improved by controlling the TE21 configuration for a conical horn and the TE11 configuration for a rectangular horn.

[Brief explanation of drawings]

Fig. 1 is a schematic configuration diagram of a conventional horn reflector antenna, Figs. 2 to 6 are explanatory diagrams of conventional characteristics, Fig. 7 is an equivalent circuit diagram of the horn reflector antenna, and Fig. 8 is an embodiment of the present invention. FIG. 9 is a schematic configuration diagram of an example, and FIG. 9 is a partially detailed diagram of the device shown in FIG. The same symbols throughout the drawings indicate the same contents or the same equivalent parts, 20 is a TE21 attitude generator, 21 is a phase compensator,
22 is a blowing horn, 23 is a wavefront converter, 24 is a power supply input terminal, and 25 is an antenna aperture.

Claims (1)

[Claims] 1. An antenna device comprising a blowing horn and a wavefront converter connected to the blowing horn, including means for providing a specific Ushiku attitude in the preceding stage of the blowing horn, and the specific higher-order attitude provided by the means. An improved cross-polarization antenna device, comprising means for making the phase of the wavefront converter opposite to that of the basic configuration.