JP2922562B2 - Corrugated horn antenna - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a corrugated horn antenna used as a primary horn of a reflector antenna.

[Conventional technology]

FIG. 2 is, for example, shown in Material A. P89-22, p. 17 (1989-6-16) of the Institute of Electronics, Information and Communication Engineers Antenna Propagation Research Group.
It is a block diagram of a conventional corrugated horn antenna.
In the figure, 1 is a corrugated conical horn in which a large number of fins are periodically arranged along a tube axis inside a conical horn, 2a, 2
b is a feeding waveguide for a low frequency band, 3 is a circular waveguide 4a, 4b
And higher mode generation unit of the TM ₁₁ mode configured tapered waveguide 5a, from 5b, 6 is a feed waveguide for the higher frequency band.

In the corrugated horn antenna configured as described above, the radio waves in the low frequency band are fed from the feed waveguides 2a and 2b, and then converted into a corrugated mode having good radiation characteristics by the corrugated conical horn 1, and from the opening. Radiated. Since the inner diameter of the waveguide at the position where the feed waveguides 2a and 2b are set is determined by the value of the lower frequency, the inner diameter of the waveguide is reduced to a portion near the high-frequency feed waveguide 6 having a sufficiently small inner diameter. It is difficult to provide. Therefore, the mode is switched to the unnecessary higher-order mode at a portion where a part of the radio wave of the high frequency band fed from the feeding waveguide 6 enters the corrugated conical horn 1. Therefore, a higher-order mode generator 3 is provided to cancel the unnecessary higher-order mode. Higher mode generated in the portion that enters into the corrugated conical horn 1 is mainly HE ₁₂ mode, this mode corresponds to the TM ₁₁ mode of the circular waveguide. Therefore, the higher-order mode generator 3 outputs a desired amount of TM ₁₁
By generating mode, it is possible to offset the HE ₁₂ mode unnecessary. Further, the higher-order mode generator 3
Is higher in order to obtain a good radiation characteristic in the two frequencies of the frequency has a structure combining two circular waveguide and two tapered waveguides with different inner diameter, the TM ₁₁ mode at two frequencies A desired generation amount can be obtained.

[Problems to be solved by the invention]

As shown in FIG. 2, since the conventional corrugated horn antenna is configured as described above, two frequencies f ₁ and f ₂ (f ₂ > f ₁ ) in a high frequency band requiring good radiation characteristics are required.
If the widely separated, when generating the TM ₁₁ mode at a frequency f _1, in addition to the TM ₁₁ mode at the frequency f ₂
TE ₁₂ mode occurs. Therefore, in order to unnecessary TE ₁₂ mode occurs other desired TM ₁₁ mode at the frequency f _2, the reflection pattern of the corrugated horn antenna is disadvantageously deteriorated.

In yet a frequency f _2, it is difficult to control both the amount of generation of emissions and TE ₁₂ modes TM ₁₁ mode in terms of freedom of design parameters, to effectively utilize these two higher order modes And it is difficult to obtain a good reflection pattern in the corrugated horn antenna.

The present invention has been made in order to solve the above-described problems. Even in a large number of frequency bands and widely separated frequencies, a cross polarization component is small and a main polarization component has a desired shape. An object of the present invention is to obtain a corrugated horn antenna having excellent radiation characteristics.

[Means for solving the problem]

Corrugated horn antenna according to the invention are used out a low frequency band, the two high frequency bands that require good radiation characteristics (f _1, f _2, and f ₁ <f _2), from the opening side In a corrugated horn antenna in which a corrugated conical horn, a higher-order mode generator, and a feed waveguide are sequentially connected, the higher-order mode generator is connected to three circular waveguides having different inner diameters (A, B, and and C), and it consists of three tapered waveguides connecting the respective circular waveguides and the feed waveguide, the inner diameter D _a of the circular waveguide a, 1.22 times the wavelength of the frequency f ₂ and a value within the range of 1.7 times, the inside diameter D _b of the circular waveguide B, and 1.7 times the wavelength of the frequency f ₂ 2.23
Times, or, the frequency f from 1.7 times the wavelength of the frequency f ₂
The value is within a range of 1.22 times the wavelength of _1.
The inner diameter D _c, is obtained by a value within the range of 1.7 times 1.22 times the frequency f _1.

[Action]

In the present invention, if the two frequencies of the high frequency band that requires good radiation characteristics and _{f 1, f 2 (f 2} > f 1), the desired occurrence of the frequency f ₁ TM ₁₁ mode In order to obtain this, the length of the circular waveguide C and the opening angle of the tapered waveguide connected to the circular waveguide C can be designed. In this case, the frequency f ₂
In the discontinuous portions at both ends of the circular waveguide C, TM ₁₁ mode and TE
₁₂ modes occur. Next, the TE generated earlier at frequency f ₂
Obtains a desired generation amount of TE ₁₂ mode after considering the ₁₂ mode, opening angle of the tapered waveguide connected to the length of the circular waveguide B in the circular waveguide B to achieve this amount of generated To design. Therefore, it is possible to consider the TE ₁₂ mode generated by the discontinuity of the two ends of the two ends and a circular waveguide B of the circular waveguide C, and control the generation amount. Specifically, the generation amount can be set to zero. Next, TM
₁₁ modes also occur, so after taking this amount into account,
The desired amount of TM ₁₁ mode is determined, and the length of the circular waveguide A and the opening angle of the tapered waveguide connected to the circular waveguide A are designed so as to realize this amount. The inner diameter of the circular waveguide A is not TE ₁₂ mode not occur because TE ₁₂ mode are set so as not to propagate can be designed to focus only on TM ₁₁ mode. From the above, it is possible to obtain a desired generation amount of TM ₁₁ mode at the frequency f _1, and so at the frequency f ₂ can be in both the TM ₁₁ mode and the TE ₁₂ mode to obtain a desired generation amount , Good radiation characteristics can be obtained at both frequencies.

〔Example〕

 An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing the structure of the corrugated horn antennas according to an embodiment of the present invention, reference numeral 1 is corrugated conical horn, 2a, 2b is feed waveguide for feeding the radio wave of low frequency f _0, 4c , 5c circular waveguide and the tapered waveguide for frequency f ₁ of the higher frequency band than the frequency f _0, 4b, 5b is the frequency f
Circular waveguide and tapered waveguide for controlling the amount of generation of TE ₁₂ mode for frequency f _{2 in a} frequency band higher than ₀ and f ₁ , 4a, 5a
It is for frequency f _2, a circular waveguide and the tapered waveguide to control the generation amount of TM ₁₁ mode. Where the inner diameter of the circular waveguide 4c
D _c is sized to TM ₁₁ mode propagates without TE ₁₂ mode propagates in the frequency f _1. Then the inner diameter D _b of the circular waveguide 4b is not TM ₁₁ mode propagates in the frequency f _1, and the frequency f ₂
In this case, the dimension is such that the TE ₁₂ mode propagates without the TM ₁₂ mode propagating. Moreover the inner diameter D _a of the circular waveguide 4a is sized to without TE ₁₂ mode propagates in the frequency f ₂ is TM ₁₁ mode propagates. From the above, the inner diameter of each circular waveguide is given by the following equation.

However, in the equations (1) to (3), C is the speed of light, K
_TM11 (= 3.83) is TM ₁₁ mode cutoff wave number, K _TE12 (= 5.3
3) indicates the cut-off wave number in the TE ₁₂ mode, and K _TM12 (= 7.02) indicates the cut-off wave number in the TM ₁₂ mode. Further, if the wavelengths of the respective frequencies f ₁ and f ₂ are λ ₁ and λ ₂ , the expressions (1) to (3) are as follows: 1.22λ ₁ <D _c <1.70λ ₁ (4) 1.70λ ₂ < D _b <{2.23λ ₂ or smaller _{1.22λ 1} ...... (5) 1.22λ} 1 <D a <1.70λ 2 ...... becomes (6).

In the corrugated horn antenna having such a structure, the frequency fed from the feeding waveguide 6 for a high frequency band is used.
radio wave f ₁ and f ₂ are unnecessary higher mode in fin portion of the feed side of the corrugated conical horn 1, since it is primarily converted in part to HE ₁₂ mode, in order to offset the higher order modes of the unwanted in, it is necessary to generate the higher mode generating unit 3 a TM ₁₁ mode by a predetermined amount.

As described above, since the set as shown the internal diameter of the circular waveguide constituting a high-order mode generating section 3 above, the frequency f ₁ in the circular waveguide 4c is TM ₁₁ mode propagation and the frequency f ₂ in the circular waveguide 4b and the 4c TM ₁₁ mode and the TE ₁₂ mode propagates, TM ₁₁ mode propagating in the circular waveguide 4a.
Therefore, by each opening of the length and the tapered waveguide 5c of the circular waveguide 4c to a predetermined value, it is possible to obtain a desired generation amount of TM ₁₁ mode at a frequency f _1. Next, the frequency f ₂
In consideration of the amount of TE ₁₂ mode generated at both ends of the circular waveguide 4c, the length of the circular waveguide 4b and the tapered waveguide are adjusted so that a desired amount of TE ₁₂ mode is obtained.
Set the opening angle of 5b. In yet a frequency f _2, the circular generation of the waveguide 4b and 4c TM ₁₁ mode generated at both ends of in consideration of the, TM ₁₁ mode of the desired circular waveguide 4a so that the amount generated is obtained And the opening angle of the tapered waveguide 5a are set. Thus, in the frequency f _2, it is possible to TM ₁₁ mode, for each higher order modes TE ₁₂ mode to obtain a desired generation amount.

In this embodiment, the cross polarization component can be canceled in each of a plurality of frequency bands, so that the cross polarization component can be reduced in each frequency band.
Since it is possible to obtain a desired amount of higher-order modes that can correct the E-plane and the H-plane of the main polarization component, the main polarization component is rotationally symmetric over a wide band, and good radiation characteristics can be obtained.

〔The invention's effect〕

As described above, according to the present invention, a low frequency band and two high frequency bands (f ₁ , f ₂ , f
₁ <is used out with f ₂ to), corrugated conical horn from the opening side, the higher order mode generating unit, the corrugated horn antennas where the feed waveguide are sequentially connected, the higher mode generating section an inner diameter of three different A circular waveguide (A, B, C from the feeding waveguide side) and three tapered waveguides connecting the circular waveguides and the feeding waveguide; the inner diameter D _a, from 1.22 times the wavelength of the frequency f ₂ 1.7
And a value within the fold range, the inner diameter D _b of the circular waveguide B, 2.23 times 1.7 times the wavelength of the frequency f _2, or from 1.7 times the wavelength of the frequency f ₂ of the frequency f ₁ and a value within the range of 1.22 times the wavelength, the inner diameter D _c of the circular waveguide C, since a value within the range of 1.7 times 1.22 times the frequency f _1, TM ₁₁ mode at the frequency f ₁ desired generation amount can be obtained, and at the frequency f ₂ can be in both the TM ₁₁ mode and the TE ₁₂ mode to obtain a desired generation amount, it is possible to obtain good emission characteristics in both frequency . Therefore, cross polarization components can be canceled in each of a plurality of frequency bands, and the main polarization component E
Since it is possible to obtain the desired amount of higher-order modes that can correct the plane and the H plane, it is possible to obtain a good radiation pattern in which the cross polarization component is small in each frequency band and the main polarization component is rotationally symmetric. There is an effect that can be done.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram showing a configuration of a corrugated horn antenna according to an embodiment of the present invention, and FIG. 2 is a diagram showing a configuration of a conventional corrugated horn antenna. In the figure, 1 is a corrugated conical horn, 2a and 2b are feed waveguides, 3 is a higher-order mode generator, 4a to 4c are circular waveguides,
5a to 5c are tapered waveguides, and 6 is a feeding waveguide. In the drawings, the same reference numerals indicate the same or corresponding parts.

Continuation of the front page (56) References JP-A-63-107206 (JP, A) JP-A-58-204604 (JP, A) JP-A-3-10406 (JP, A) JP-A-3-14301 (JP) , A) JP-A-3-14302 (JP, A) JP-A-63-144714 (JP, U) IEICE Technical Report Vol. 89 No. 76 A ・ P89-22 IEICE Technical Report Vol. 88 No. 358 A ・ P88-118 (58) Fields surveyed (Int. Cl. ⁶ , DB name) H01P 1/16 H01Q 13/02 JOIS

Claims (1)

(57) [Claims] 1. A low frequency band, the two high frequency bands that require good radiation characteristic (f _1, and _{f 2, f 1 <f 2} ) the de used, corrugated conical horn from the opening side, In a corrugated horn antenna in which a higher-order mode generator and a feed waveguide are connected in sequence, the higher-order mode generator is made of three circular waveguides having different inner diameters (A, B, and C from the feed waveguide side). If, constituted by the above-mentioned circular waveguide and three tapered waveguides connecting said feed waveguide, the inner diameter D _a of the circular waveguide a, the wavelength of the frequency f ₂ 1.
From 22 parts to a value within the range 1.7 times, the inside diameter D _b of the circular waveguide B, 1 of the wavelength of the frequency f _2.
2.23 times 7 times, or, to a value within the range from 1.7 times the wavelength of the frequency f ₂ of 1.22 times the wavelength of the frequency f _1, the inner diameter D _c of the circular waveguide C, the frequency f ₁ A corrugated horn antenna characterized by a value within a range of 1.22 times to 1.7 times of.