JPH0314302A - Horn antenna - Google Patents

Abstract

PURPOSE:To increase the degree of freedom in design and to improve frequency characteristics by determining the inner diameter of a 1st taper waveguide from a horn aperture so that a TE12 mode is not cut off even in a low frequency band. CONSTITUTION:The inner diameter of the 1st taper waveguide 2 from the horn aperture is set up so that the TE12 mode is not cut off in a low frequency band but is cut off in the high frequency band and the generation quantity values of the TE12 mode in the high frequency band generated on both the ends of the waveguide 2 are equal to each inner and their phases are reversed from each other in the horn aperture. The inner diameter of a 3rd taper waveguide 4 is set up so that the TM11 mode is not cut off but the TE11 mode is cut off in both the low and high frequency bands and the taper waveguide 6 having an inner diameter set up so that the TM11 mode is cut off in the low frequency band but is not cut off in the high frequency band is added to the feeding terminal side. Consequently, the inner diameter of the taper waveguide 2 can be increased, the degree of freedom in design can be increased and the frequency characteristics can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an improvement of a dual-frequency dual-mode horn antenna used in a microwave band or a millimeter wave band.

[Conventional technology]

Figure 2 is a cross-sectional view showing an example of a conventional dual-frequency dual-mode horn antenna.
j (21 is the first taper waveguide, (3) is the second taper waveguide, (4) is the third taper waveguide, (5》
is the fourth tapered waveguide.

Next, the operation will be explained.

A multi-mode horn antenna excites using the fundamental mode of a circular waveguide, TEj mode, and higher-order modes. Good cross-polarized wave characteristics can be obtained by excitation so as to cancel out the cross-polarized wave components generated during excitation. In addition, the difference between the E-plane pattern and the H-plane pattern that occurs when only the T]Jj mode is excited is reduced by exciting the higher-order modes in combination. It is possible to obtain a pattern that is close to rotational symmetry. Higher-order modes include TMB mode and TE12.
mode is used. These higher-order modes are generated by discontinuities inside the circular waveguide that allow higher-order modes to propagate (i.e., without cutoff), and as the diameter of the circular waveguide increases, the TMII mode t'rxl2
Occurs in order of mode. Normally, when using only the TM1j mode in a dual-frequency dual-mode horn, the inner diameter of the first tapered waveguide (2) from the horn opening is set to the low frequency band.
In the high frequency band, the TM 11 mode is not cut off, but the 'rE 12 mode is cut off.
The inner diameter of the third tapered waveguide (4) from the horn opening is set to a diameter where the TM11 mode is cut off at low frequencies, but the TMil mode is not cut off at 7 at high frequencies) s TM+1 It is possible to individually adjust the amount and phase of mode generation in the low frequency band and high frequency band, and good characteristics can be obtained in both frequency bands.

[Problem to be solved by the invention]

Conventional horn antennas are configured as described above, so in the case of a multi-mode horn that uses only the TM11 mode as the higher-order mode, the constraint on the inner diameter of the first Taber waveguide (2) from the horn opening ,Horn(!)
Depending on the dimensions of the mode, it may be physically impossible to obtain the desired amount and phase of the 'rn11 mode in the high frequency band. Additionally, there were other problems such as deterioration of frequency characteristics due to the longer distance between the horn aperture and the Taber waveguide section that generates higher-order modes.

This invention was made in order to solve the above-mentioned problems, and by relaxing the constraint on the inner diameter of the first tapered waveguide from the horn opening, increasing the degree of freedom in design.
An object of the present invention is to obtain a horn antenna with improved frequency a characteristics.

[Means to solve the problem]

In the horn antenna according to the present invention, the inner diameter of the first Taper waveguide from the horn opening is such that the TE12 mode has a cutoff of 7 in a low frequency band but does not have a cutoff in a high frequency band, and this tapered waveguide The inner diameter of the third tapered waveguide from the horn opening is adjusted so that the amount of TE12 mode in the high frequency band generated at both ends of the TE12 mode is approximately equal to each other and almost in opposite phase at the horn opening. Although TJJ mode is not cut off to 7 in the belt, 'rx
12 mode has a diameter of cutoff 7, and TM 1
A tapered waveguide with a diameter that cuts off mode 1 in low frequency bands but does not cut off in high frequency bands is added to the feeding end side.

[Function] As described above, by holding the horn, the inner diameter of the first tapered waveguide from the horn opening can be narrowed.
This increases the degree of freedom in design and improves frequency characteristics.

〔Example〕

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

In FIG. 1, {1} is a horn, and (2) to (7) are tapered waveguides having different taper angles.

The inner diameter of the first tapered waveguide (2) from the horn opening is
Conventionally, it was necessary to select a diameter that would cause the Tl12 mode to have a cutoff of 7 even in high frequency bands, but in this invention, the diameter should be selected such that the Tl12 mode does not have a cutoff of 7 even in high frequency bands. can be made larger. At this time, TE12 mode occurs in the high frequency band. TM11
In a multi-mode horn antenna designed to use only modes, the generation of the TE12 mode is a factor in deteriorating the characteristics, so the amount of T11!12 modes generated at both ends of the tapered waveguide (2) is almost equal to each other, and the horn opening The Taper angle and length of the tapered waveguide (2), and the Taber angle of the second Taper waveguide (3) from the horn opening are determined so that the phases are almost opposite to each other. Next, the TM in the low frequency band generated at both ends of the first tapered waveguide (2) from the horn opening and at both ends of the third tapered waveguide (4) from the horn opening.
The taper angle and length of the tapered waveguide (4) and the taper angle of the fourth tapered waveguide (5) from the horn opening are adjusted so that the H-mode composite wave has the desired generation amount and phase. decide. At this time. The inner diameter of the tapered waveguide (4) is set to such a diameter that the TM11 mode is not cut off in both the low frequency band and the high frequency band, but the TE12 mode is cut off.

Next, the composite wave of the TM11 mode in the high frequency band generated at both ends of the tapered waveguide (2), both ends of the tapered waveguide (4), and both ends of the fifth tapered waveguide (6) from the horn opening is generated. The taper angle and length of the tapered waveguide (6) and the taper angle of the sixth tapered waveguide (7) from the horn opening are determined so as to obtain the desired generation amount and phase. At this time, the inner diameter of the Taber waveguide (6) is set so that the TM11 mode is cut off in a low frequency band, but not in a high frequency band.

By configuring as described above, it is possible to individually adjust the amount and phase of the be TM11 mode in the low frequency band and the high frequency band, and good characteristics can be obtained in both frequency bands.

In addition, in the above embodiment, a multi-mode horn antenna designed using only the TM1j mode was shown. Occurs at both ends of the first tapered waveguide {2} from the horn opening.'
The high frequency In the band, TE12 mode and TM11 mode are used,
It can also be applied to multi-mode horn antennas designed to use only the TM11 mode in low frequency bands.

〔Effect of the invention〕

As described above, according to the present invention, T as a higher-order mode
In a multi-mode horn antenna designed to use only the MH mode, the inner diameter of the first tapered waveguide from the horn opening can be made larger than before, increasing the degree of freedom in design and generating higher-order modes. As the distance between the part and the horn opening becomes shorter, the frequency characteristics are improved.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional side view showing a horn antenna according to an embodiment of the present invention, and FIG. 2 is a cross-sectional side view showing a conventional horn antenna. In the figure, (0 is a horn, and (2) to (7) are Taber waveguides. In the figure, the same reference numerals indicate the same or corresponding parts. Cooper conductor pipe No. 2!!I

Claims (2)

[Claims] (1) In a horn antenna configured by connecting multiple taper waveguides that are shared by two frequency bands and have different taper angles, the horn antenna is configured by connecting a horn and six taper waveguides, and from the horn opening The inner diameter of the first tapered waveguide is set so that in the low frequency band, the TM_1_1 mode is not cut off, but the TE_1_2 mode is cut off, and in the high frequency band, neither the TM_1_1 mode nor the TE_1_2 mode is cut off. The inner diameter of the third tapered waveguide is T in both the low frequency band and the high frequency band.
M_1_1 mode does not cut off, but TE_1_
For mode 2, the diameter is cutoff, and the diameter is 5 mm from the horn opening.
The inner diameter of the second tapered waveguide is TM_1_ in the low frequency band.
1 mode is cutoff, but in high frequency band TM_
The 1_1 mode has a diameter that does not result in cutoff, and the TE_ in the high frequency band that occurs at both ends of the first tapered waveguide.
A horn antenna characterized in that the amounts of 1_2 modes generated are substantially equal to each other and have substantially opposite phases at the horn opening. (2) In a horn antenna configured by connecting multiple taper waveguides that are shared by two frequency bands and have different taper angles, the horn antenna is configured by connecting a horn and six taper waveguides, and from the horn opening The inner diameter of the first tapered waveguide is set so that in the low frequency band, the TM_1_1 mode is not cut off, but the TE_1_2 mode is cut off, and in the high frequency band, neither the TM_1_1 mode nor the TE_1_2 mode is cut off. The inner diameter of the third tapered waveguide is T in both the low frequency band and the high frequency band.
M_1_1 mode does not cut off, but TE_1_
For mode 2, the diameter is cutoff, and the diameter is 5 mm from the horn opening.
The inner diameter of the second tapered waveguide is TM_1_ in the low frequency band.
1 mode is cutoff, but in high frequency band TM_1
_1 mode is a horn antenna characterized by having a diameter that does not cut off.