JPH04238404A - Scalar feed horn - Google Patents

Abstract

PURPOSE:To use a scalar feed horn in a wide frequency band by providing concentric circular chokes in specified angle areas with respect to the direction of respective linearly polarized waves as against respective linearly polarized waves to which two frequencies are orthogonally linearlly polarized wave-fed and setting the radiation patterns of respective frequencies to be satisfactory patterns symmetric as against an axis. CONSTITUTION:The scalar feed horn has a horn which is formed by a circular waveguide 3 and the concentric circular chokes 2a and 2b suppressing a backward current at the external side of the opening surface 1. Then, the scalar feed horn common to the two frequencies of the orthogonally linearly polarized wave, in which the electromagnetic wave of a first frequency is fed by a vertically polarized wave, and the electromagnetic wave of a second frequency is fed by a horizontally polarized wave, is formed. Here, the first concentric circular choke suppressing the backward current in the first frequency in the angle of + or -45 deg. as against the direction of the electromagnetic wave fed by the first frequency and the choke suppressing the backward current in the second frequency is given to the angle area of + or -45 deg. as against the direction of the polarized wave of the electromagnetic wave fed by the second frequency.

Description

[Detailed description of the invention]

0001

[Industrial Field of Application] The present invention relates to a scalar feed horn used as a primary radiator such as a parabolic antenna, and in particular to a scalar feed horn for orthogonal linearly polarized dual frequency bands used in the microwave band and quasi-millimeter wave band. Concerning the feed horn.

0002

2(a) and 2(b) show structural diagrams of an example of a conventional scalar feed horn. Figure 2
2(a) shows a front view, and FIG. 2(b) shows a sectional view thereof. In the figure, 1 is the horn opening surface, 6 is a concentric choke provided on a surface receding from the horn opening surface 1, 3 is a circular waveguide that forms the horn, and 4 is a power supply to the circular waveguide 3. Vertical polarization of electromagnetic waves, 5 also represents horizontal polarization. The dimension L1 indicates the distance between the pawn opening surface 1 and the surface of the concentric choke 6 on the surface recessed from the pawn opening surface 1, and is usually determined experimentally as a dimension that provides good radiation pattern characteristics of the scalar feed horn. The dimension L2 indicates the depth of the concentric choke 6, and is often selected to be 1/4 wavelength of the center frequency of a commonly used two-frequency band.

[0003] This scalar feed horn is one that can be used for two frequency bands that form orthogonal linearly polarized waves, and a polarization splitter (not shown) that can be used for two frequency bands is usually used to feed the scalar feed horn. Ru. The linearly polarized waves in the low frequency band and the high frequency band are orthogonal to each other, and the two frequencies feed the circular waveguide 3 of the scalar feed horn with independent linearly polarized waves that have little interference with each other. These supplied electromagnetic waves, for example, a horizontally polarized wave 5 in a low frequency band and a vertically polarized wave 4 in a high frequency band, are directed forward from the horn aperture 1 of the scalar feed horn (to the right in Fig. 2(a)). is emitted. This radiation pattern is determined by the amplitude distribution and phase distribution on the horn aperture surface 1, and in the frequency band used, the E-plane pattern of the surface containing the electric field and the H-plane pattern of the surface containing the magnetic field are approximately equal. The goal is to have a symmetrical beam. The means are a concentric choke 6 and an appropriate dimension L1. The concentric choke 6 plays the role of suppressing the backward current flowing outside the horn opening surface 1, that is, the outer wall surface of the circular waveguide 3, and suppresses pattern deterioration caused by this current. . When the dimension L2 is selected to be 1/4 wavelength of the frequency used, the current suppressing effect as a choke is significantly exhibited, and good results can be obtained. In addition, the dimension L1 is experimentally determined while adjusting so that the pattern on the E surface and the pattern on the H surface are approximately equal in shape, and when the desired amplitude distribution and phase distribution are achieved, the pattern on the E surface and the pattern on the H surface are
An axially symmetrical beam radiation pattern with substantially uniform surface patterns is achieved.

0004

[Problems to be Solved by the Invention] However, in the conventional scalar feed horn, the dimension L
The effects obtained with 1 and L2 can be easily achieved at a certain frequency because they are a single frequency, but when used in a wide frequency band, the optimum effect determined by each frequency is required. It is difficult to obtain a good radiation pattern because of deviations in the dimensions. Especially 2
When used in two frequency bands, this deviation becomes increasingly large at the lower limit frequency and upper limit frequency, and performance deterioration is unavoidable. As a result, the wall current suppression effect is reduced, the amplitude distribution and phase distribution on the horn aperture are disturbed, and the radiation pattern, especially the E-plane pattern, deteriorates and is no longer aligned with the H-plane pattern. .

[0005] The object of the present invention is to improve E over a wide frequency band.
An object of the present invention is to provide a scalar feed horn with uniform plane and H-plane radiation patterns.

[0006]

[Means for Solving the Problems] The scalar feed horn of the present invention includes a horn formed by a circular waveguide;
It has a concentric choke on the outside of its aperture surface to suppress backward current, and has an orthogonal choke in which electromagnetic waves of a first frequency are fed by vertically polarized waves, and electromagnetic waves of a second frequency are fed by horizontally polarized waves. In a scalar feed horn that can be used for both linearly polarized waves and two frequencies, a first concentric circle that suppresses a backward current of the first frequency in an angular region of ±45° with respect to the direction of the electromagnetic wave fed at the first frequency. a second concentric choke that suppresses a backward current of the second frequency in an angular region of ±45° with respect to the polarization direction of the electromagnetic wave fed by the second frequency; have.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be explained with reference to the drawings.

FIGS. 1(a) and 1(b) are structural diagrams showing one embodiment of the scalar feed horn of the present invention. FIG. 1(a) is a front view, and FIG. 1(b) is a sectional view taken along line A-B. In the figure, 1 is the horn opening surface, 2 (2a and 2b) is a concentric choke provided on the outside and receding surface of the horn opening surface 1, 3 is a circular waveguide forming the horn, and 4 is a circular waveguide. 5 represents a vertically polarized wave generated by an electromagnetic wave of a first frequency fed to the tube 3, and a horizontally polarized wave generated by an electromagnetic wave of a second frequency. The concentric choke 2 is provided on the outer wall surface of the circular waveguide 3. The concentric choke 2a is ±
A concentric choke 2b provided within an angular area of 45°
are provided within an angular range of ±45° with respect to the direction of the horizontally polarized wave 5. Therefore, the concentric chokes 2a and 2
In b, 1/4 concentric circles having the same diameter are alternately and consecutively provided. Dimension L3 is the concentric choke 2a
The depth and dimension L4 indicate the depth of the concentric choke 2b. The dimension L3 of the concentric choke 2a is vertically polarized 4
The dimension L4 of the concentric choke 2b is set to be 1/4 wavelength at the second frequency that generates the horizontally polarized wave 5. Here, since the first frequency is higher than the second frequency, the dimension L3 is shorter than the dimension L4.

In such a scalar feed horn, the vertically polarized electromagnetic wave 4 of the first frequency is directed to the horn opening surface 1 by a concentric choke 2a with a depth L3 provided in the direction of the polarized wave. The backward current flowing outside is effectively suppressed. On the other hand, regarding the electromagnetic wave of the horizontally polarized wave 5 of the second frequency, the concentric choke 2 is similarly provided in the direction of the horizontally polarized wave 4 where the backward current is at the depth L4.
b is effectively suppressed. That is, the dimensions L3 and L4 are set in the optimum direction and depth for each polarized electromagnetic wave.
is determined, so the current suppressing effect as a choke is significantly exhibited. As a result, even if the first and second frequencies are far apart, the desired amplitude distribution and phase distribution can be achieved at each frequency, and this scalar feed horn has an axially symmetrical structure in which the E-plane pattern and the H-plane pattern are almost equal. A beam radiation pattern can be obtained.

In this embodiment, the concentric chokes 2a and 2b are provided on a plurality of concentric circles in order to increase the backward current suppression effect, but depending on the desired performance, they may be provided on only one concentric circle. It's okay to be lazy.

[0011] Furthermore, when the first and second frequencies have bands, it is sufficient to make those frequency bands representative by approximately the center frequency of each frequency band.

0012

Effects of the Invention As explained above, the scalar feed horn of the present invention has an angle of 45° with respect to the direction of each linearly polarized wave for each linearly polarized wave to which two frequencies are fed with orthogonal linearly polarized waves. By providing concentric chokes in the angular region, the radiation pattern at each frequency can be made into a good axially symmetrical pattern, which has the effect of allowing use in a wide frequency band.

[Brief explanation of the drawing]

FIG. 1 is a structural diagram of an embodiment of the present invention, in which (a) is a front view and (b) is a sectional view taken along the line AB.

FIG. 2 is a structural diagram of a conventional scalar feed horn, in which (a) is a front view and (b) is a sectional view thereof.

[Explanation of symbols]

1 Horn opening surface 2, (2a, 2b) Concentric choke 3
Circular waveguide 4 Vertical polarization 5 Horizontal polarization 6 Concentric choke

Claims (2)

[Claims] Claim 1: A horn formed by a circular waveguide, and a concentric choke for suppressing backward current on the outside of the aperture thereof, and an electromagnetic wave of a first frequency is fed by vertically polarized waves. , in an orthogonally linearly polarized two-frequency scalar feed horn in which an electromagnetic wave of a second frequency is fed by horizontal polarization, the above-mentioned in an angular region of ±45° with respect to the direction of the electromagnetic wave fed with the first frequency; a first concentric choke for suppressing a backward current of the first frequency; the second concentric choke is arranged in an angular region of ±45° with respect to the direction of polarization of the electromagnetic wave fed by the second frequency; A scalar feed horn characterized by having a second concentric choke that suppresses current flowing backward in frequency. 2. The scalar feed horn according to claim 1, wherein the first concentric choke and the second concentric choke are successively arranged on the same concentric circle.