JPS5897902A - Reflector type antenna device - Google Patents

Abstract

PURPOSE:To make an irradiation area slightly different for every frequency band by setting the phase center of a primary horn to the focal point of a parabolic reflector for one frequency band, and shifting it from the focal point for the other frequency band and also selecting an angle of feeding to the reflector. CONSTITUTION:A multifrequency common-use antenna for mounting on an artifricial satellite has an offset parabolic reflector 1 fed by a multifrequency common-use primary horn 2. In a frequency band having a phase center point 8, the direction of a radiant beam of the antenna is specified without reference to an angle 4 of feeding. In a frequency band having a phase center point 9, a phase distribution in the opening surface of the reflector 1 is not vertically symmetrical in Fig. according to variation in feeding angl 4. As a result, the direction of the radiant beam of the antenna varies vertically. For this purpose, the feeding angle 4 is selected to obtain a slightly different irradiation area for each frequency band, incrasing a minimum gain in the irradiation area.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a reflecting mirror antenna device used in the microwave band, and provides an antenna that can be used in two or more multiple frequency bands and further covers irradiation areas that differ somewhat depending on the frequency band. It is something.

Generally, this woodcutter's antenna is used, for example, as an antenna onboard an artificial satellite, with a beam of one frequency band covering an area, and a beam of another frequency band, mostly overlapping but slightly shifted. They are used when it is necessary to cover an area.

As a conventional multi-frequency band antenna mounted on an artificial satellite, an offset parabolic antenna as shown in FIG. 1 is often used. That is, offset parabolic reflection @
It has a structure in which the phase center of the charging horn (2) coincides with the focal point of ill+, (31 is the aperture diameter, (4) is the feed angle, and (5) is the aperture angle. In the case of a charging horn that shares a band, the phase center point is for the circumference and several bands for which the highest gain is desired.

Moreover, the feeding angle (4) is an angle that looks at the center of the aperture angle +51 of the reflecting mirror (1), and fishing is carried out by feeding electricity. In this case, the center directions of the radiation beams in each frequency band are approximately the same.

Therefore, as shown in Figure 2, if the irradiation area (6) in one frequency band is different from the irradiation area (7) in another frequency band, the direction of the antenna should be aligned with the center of the irradiation area 16). Then, the minimum gain within the irradiation area in this frequency band becomes maximum, but for the irradiation area (7), since the center direction of the beam in this frequency band is at the center of the irradiation area (6), the irradiation area The disadvantage is that the minimum gain within the range is low.

This invention aims to solve this conventional drawback.

Multi-frequency band sharing - Using the fact that the phase center point of the next horn is different for each frequency band, the direction of the antenna's radiation beam can be changed depending on the nine frequency bands by changing the feed angle t to one reflecting mirror. Therefore, the drawings will be explained in detail below.

FIG. 3 shows an embodiment of the present invention, where is an off-nut parabolic reflector, (2) is a charging horn that can be used for multiple frequency bands, Ial is the aperture diameter of the reflector, and (4) is the feeding angle. (5)
is the aperture angle of the reflecting mirror, (8) is the phase center point at the 18th wave with the highest gain, and (9) is the phase center point for other frequency bands.

In Figure 3, in the frequency band of the 2nd position center point (8), the direction of the antenna radiation beam is constant regardless of the feeding angle (4), but in the frequency band of the 1st phase center point (9), the direction of the antenna radiation beam is constant regardless of the feeding angle (4).
As the value changes, the phase distribution on the aperture surface of the 0 reflecting mirror is no longer symmetrical in the vertical direction in FIG. As a result, the direction of the radiation beam of the antenna also changes in the vertical direction.

The fourth factor is the opening diameter (3) of 21111. Aperture angle (5) is 9
1 frequency is 2 with 0.3 degree offset parabolic reflector mountain
5-1 Regarding the cases of Fig. 4(a) and 5.925 GHz Fig. 4(b), the radiation noise when the feeding angle (4) t changes (
An example of calculation of ter/ is shown. Figure 4(a) shows frequency 2
．． 5GHz.

The contour mt of a gain of 30 dB in right-handed circularly polarized waves is shown. The solid line shows the case where the feeding angle is 55.2 degrees, and the broken line shows the case where the feeding angle is 6a, 5 degrees. Also, Fig. 4(b) is frequency 5.925G
Hz.

The graph shows a contour silver with a gain of 33di+ in left-handed circularly polarized waves, the solid line shows the case where the feeding angle is 55.2 degrees, and the broken line shows the case where the feeding angle is 65.5 degrees. In this case - order ho y (21tj frequency 2.
The phase center point (8) at 5 GHz coincides with the focal point of the reflecting mirror mountain, and the phase center point (9) at 1 frequency 5.925 GIiz
) is located out of focus. From Figure 4 9 Frequency 2
．． At 5 GHz, the center direction of the radiation beam hardly changes even if the feed angle (4) changes.

At a frequency of 5.925 GHz, the center direction of the radiation beam is shifted by about 0.35 degrees in the vertical direction. At this time, the change in gain in the direction of the center of the radiation beam is 0.3 dB at a frequency of 2.50 oz, and the frequency and wave number are 5.92.
It was 0.7 dB at 5 GHz.

No. 5N is a side configuration diagram showing another embodiment.

Figure 6 is a front view of the fifth garden. Charging horn (21 is a reflecting mirror (11's focal point and gain t-
The phase center point of the frequency band that is desired to be the highest coincides with +8)-1)E, and the feed angle (4) is shifted by an angle +11 in the orthogonal direction from the target plane including the focal point of the reflecting mirror surface +11. As a result, the center direction of the antenna beam is in the front direction of the 1st reflector (1) for the 2nd phase center point (8), but in the left-right direction by an angle αC for the 9th phase center point (9). It will shift to Therefore, the center deviation n in the left-right direction
Efficiency in all two irradiation areas and two frequency bands.
In addition, when using a laboratory reflective key antenna in a frequency band and using circularly polarized waves with different rotation directions, even if the phase center points +81 and 191 coincide, the offset type Due to the cross-polarized waves generated by the reflection d111, the force in the center direction of the beam is shifted in opposite directions on the left and right with respect to the front direction of the mirror (1), but according to this invention, the phase center point (8) Angle (1G by 1G) with respect to the center direction of the beam in the frequency band
The center direction of the beam in the frequency band of the phase center point (9) can be set at a predetermined position in the left-right direction.

FIG. 7 shows another embodiment, in which till is a rotationally symmetrical parabolic reflector, and a multi-frequency band common -order horn (2
), the focal point of the reflection fitll and the phase center point (8) of the round ea, which greatly reduced the gain, coincide.

The feeding angle a21 is the angle 0z from the central axial force 1 of the reflecting mirror (III).
It's shifted by just that. As a result, the IC inside the beam of the antenna
? The direction is the reflector (Ill) for the 9 phase center point (8).
However, with respect to the 1 phase center point (9), the frontal force of the reflecting mirror aD is shifted by the angle gu11.Therefore, the frequencies of all two irradiation areas whose centers are shifted are Efficiency work〈cough (-) can be crab.

As explained above, according to the present invention, by changing the feeding angle (4), the central direction of the radiation beam at the frequency of the phase center point (8) at the focal point of one reflecting mirror mountain is changed at a substantially constant t\9. Since the center direction of the phase center point (91 circumference i21!) of the radiation beam can be changed, it can be used as a multi-frequency band antenna for use onboard artificial satellites, etc., which requires slightly different irradiation areas in 9 frequency bands. This has the advantage that the minimum gain within the region can be increased.

[Brief explanation of drawings]

Figure 1 is a configuration diagram of a conventional antenna, the second factor is a diagram showing the irradiation area, Figure 3 (8) is a configuration diagram of an antenna showing an embodiment of the present invention, and Figure 4 is an embodiment of the present invention. The HS diagram is a tooth surface configuration diagram showing another embodiment of the present invention, and the sixth figure is a front configuration diagram of FIG. 5. FIG. 7 is a block diagram of #f showing another embodiment of the present invention. di...offset parabolic reflector, 12+...
-th order ho-y, +31...Aperture diameter, (4)...Feeding angle, (5)...Aperture angle. +61. +71...irradiation area, +81. +91
...Phase center point, u--Rotationally symmetrical parabolic reflection-1 Note that the same or corresponding parts in Figure 1 are denoted by the same reference numerals. Figure 1 ＼ Figure 2 Figure 3, 'I Yo Castle 9 Ko 115 Figure 61! l Figure 7

Claims (1)

[Claims] A reflector type antenna device comprising a parabolic reflector and a multi-frequency band common horn. By aligning the phase center of the -order Ho/ with the focus of the parabolic reflector for one frequency band, and shifting it from the focus of Fi for other frequency bands, and selecting the feeding angle to the reflector, the antenna can be A reflecting mirror antenna device characterized in that the direction of the radiation beam is shifted depending on each frequency band.