JPS6017164B2 - horn antenna - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electromagnetic horn used in the microwave band or millimeter wave band, which is capable of controlling the fundamental modes of a circular waveguide, TE, . The present invention relates to a multimode horn antenna that is excited using modes and higher-order modes.

Conventionally, such a multi-mode horn antenna has a conical horn 1, a straight circular waveguide 2, and a tapered waveguide 4 connected to a feeding waveguide 3, as shown in FIG. There was a model in which iris 5 was provided. However, although it is possible to obtain the generation amount and phase of higher-order modes necessary for a multimode horn antenna within a narrow frequency band with this configuration, it is difficult to obtain good performance over a wide frequency band. was there. In addition, when trying to achieve relatively good frequency characteristics, there are restrictions on the diameter or opening angle of the conical horn 1, which makes it difficult to achieve the necessary gain as a horn antenna. The disadvantage is that it is difficult to adjust the higher-order modes. In order to eliminate these drawbacks, this invention consists of a conical horn 1, two linear circular waveguides 2a, 2b with different diameters, two tapered waveguides 4a, 4b, a feeding waveguide 3, and a metal band 6. The feature is that a plurality of metal bands 6 are provided inside one or both of the two linear circular waveguides in the tube axis direction, and the aperture diameter and opening angle of the horn can be adjusted to obtain the required gain. At the same time, it generates the necessary higher-order modes over a wide frequency band, and when using circularly polarized waves, there are few cross-polarized components, and when using linearly polarized waves, it generates E-plane and H-plane beams. The purpose is to obtain a uniform and good radiation pattern, and the drawings will be explained in detail below.

FIG. 2 shows an embodiment of the present invention, in which a straight circular waveguide 2a
, 2b have metal bands 6a, each having a rectangular cross section.
6b, 6c, and 6d are provided. From the feeding waveguide 3, the fundamental mode TE, . When the mode is incident, a part of the mode is converted into a higher-order mode at the interface between the tapered waveguides 4a and 4b and the straight circular waveguides 2a and 2b. Furthermore, metal bands 6a, 6
Higher-order modes also occur at locations b, 6c, and 6d. A multimode horn antenna uses the antenna as the fundamental mode T.
E. TE, . It is designed to excite by combining modes and higher-order modes. The conditions for the higher-order mode that make it possible to obtain good characteristics as a multi-mode horn antenna are such that the power pattern and phase pattern of the cross-polarized components of this higher-order mode are such that the shape of the power pattern and the phase pattern are TE,
．． The shape of the power pattern and phase pattern of the cross-polarized components of the mode are similar. Therefore, such higher-order modes include TM, . mode, TEM mode, etc. These higher order modes are generated by discontinuities within the circular waveguide through which they can propagate. In this case, if the parts constituting the antenna are mechanically rotationally symmetric, as the diameter of the circular waveguide increases, the TM
、． Mode, TE, and 2 modes occur in this order. The conditions necessary to obtain good characteristics as a multimode horn antenna are TE, . Mode cross-polarization component damage TE, . and TM,
．． Cross polarization component of mode *TM, . and TE, the cross polarization component of two modes*TE,2 becomes zero.

That is, it is expressed by the following equation. ×TE,. 10*TM,. 10×TE2=0′1} Furthermore, in order to obtain good characteristics over a wide frequency band, the following conditions must also be satisfied. MakuXTEu+XTMu+XT
E・2)=.

'21 In the above equation, f represents the frequency. In a multi-mode horn antenna, the sum of higher-order modes generated from each location must satisfy the above equations '1' and (2).

Therefore, in this invention, the diameter of the straight circular waveguide 2b is set to T
M,. The diameter of the straight circular waveguide 2a is set to be larger than the diameter of the straight circular waveguide 2a, as shown in FIG.
By setting the dimensions such that two modes propagate, the joint surface of the tapered waveguide 4b and the straight circular waveguide 2b, the metal band 6c,
6d and the joint surface between the straight circular waveguide 2b and the tapered waveguide 4a, TM, . Since only mode occurs, TM
、． It is possible to individually adjust the generation amount and phase of the two modes, TE, and TE, and by appropriately selecting a combination of them, TE, . Since cross-polarization components of modes can be canceled, when using circularly polarized waves, there are fewer cross-polarized components, and when using linearly polarized waves, the E-plane and H-plane beams are aligned. A good radiation pattern can be obtained.

The above explanation was given for the case where the metal bands 6a, 6b, 6c, and 6d were provided on both of the two straight circular waveguides 2a and 2b, but as shown in FIG. A similar effect can be obtained even if the metal bands 6a, 6b are provided only on the tube 2a.

Further, as shown in FIG. 2c, the same effect can be obtained by using step 7 instead of the tapered waveguide 4a. As described above, this invention has a predetermined gain, and has few cross-polarized components in circularly polarized waves, and in linearly polarized waves, it is possible to
Since it is possible to obtain a uniform and good radiation pattern in a plane beam, it is effective not only as a horn antenna but also as a primary radiator for a parabolic antenna or a Cassegrain antenna.

Simple test of drawings Figure 1 is a configuration diagram of a conventional multi-mode horn antenna, Figure 2 is a diagram of the configuration of a conventional multi-mode horn antenna.
The figure shows an embodiment of a multi-mode horn antenna according to the present invention.

In the figure, 1' is a conical horn, 2 is a linear circular waveguide, 3 is a feeding waveguide, 4 is a tapered waveguide, 5 is an iris, 6 is a metal band, and 7 is a step. In the drawings, the same or corresponding parts are denoted by the same reference numerals. Figure 1 Figure 2

Claims (1)

[Claims] 1 In a horn antenna used in the microwave band or millimeter wave band, when the horn antenna is viewed from the feeding side, it is a feeding waveguide, a tapered waveguide, or a step TE_1.
A straight circular waveguide, tapered waveguide or step having a diameter in which the _1 mode propagates and the TE_1_2 mode does not propagate.A straight circular waveguide, a cone, which has a diameter larger than the diameter of the above straight circular waveguide and in which the TE_1_2 mode propagates. The structure is rotationally symmetrical with respect to the tube axis to which the horns are sequentially connected, and a metal band rotationally symmetrical with respect to the tube axis is placed on the inner wall of one or both of the two linear circular waveguides in the tube axis direction. A horn antenna characterized by having a plurality of horn antennas.