JPS603211A - Antenna in common use for multi-frequency band - Google Patents

Abstract

PURPOSE:To obtain an antenna characteristic at each frequency band by arranging a primary radiator system having a high frequency band to a focus of a main reflecting mirror where plural partial mirror faces are combined so that a focal point is different from each other and arranging a primary radiator system having the lowest frequency band to the other position. CONSTITUTION:The main reflecting mirror 1' is the combination of partial mirror faces 2, 3 comprising a part of a paraboloid of revolution. Focii F2 and F3 of the partial mirror faces 2, 3 are different in their position and primary radiators 10, 11 having a high frequency band are arranged respectively at the focii F2 and F3. The primary radiator 10 irradiates mainly the partial mirror face 3 and the primary radiator 11 irradiates mainly the partial mirror face 2. Center axes Z2 and Z3 of the partial mirror faces 2, 3 are titled respectively by angles theta2, theta3 in the opposite direction to a reference axis Z mutually. Further, the 3rd primary radiator 12 having the lowest frequency band is arranged between the focii F2 and F3.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical field to which the invention pertains] The present invention relates to an antenna for microwave bands and sub-millimeter wave bands. In particular, the present invention relates to a multi-frequency band antenna that shares two or more frequency bands and has at least one transmission/reception beam for each frequency band.

[Description of prior art]

Conventionally, as this type of multi-frequency band antenna, a parabolic antenna whose configuration is shown in FIG. 1 and which is fed with power by a plurality of primary radiators is known.

In FIG. 1, reference numeral 1 indicates a main reflecting mirror having a paraboloid of revolution having a focal point F, and reference numerals 10 and 11 indicate primary radiators having different frequency bands. Since the primary radiators 10.11 are independent for each frequency band, the primary radiators 10.11
It is possible to give each directivity characteristic to obtain the required antenna gain and beam width for each frequency band.

However, the angle between each beam direction is minimized when multiple primary radiators are placed close enough to physically touch each other. For example, when you want to direct the beam in almost the same direction for each frequency band. had the disadvantage that the maximum direction of the beams could not be aligned in the same direction. In addition, in the antenna with the configuration shown in Fig. 1, the primary radiators 10 and 11 are used as the primary radiators of the communication beam, and independently of this, the self-tracking beam is set so that the zero point is within the communication beam width. When it is desired to add a primary radiator, there are drawbacks such as the fact that it becomes physically impossible to arrange the primary radiator for self-tracking.

[Purpose of the invention]

The present invention aims to improve the above-mentioned drawbacks, and is capable of independently synthesizing beams for each frequency band to obtain antenna characteristics desired in each frequency band, and by combining multiple primary radiator systems. Multi-frequency a that can be physically easily installed
The purpose is to provide a common antenna for the 'Fj'r region.

The present invention configures one main reflecting mirror by combining a plurality of partial mirror surfaces each consisting of a part of a paraboloid of revolution so that their focal positions are different from each other, and a plurality of primary radiators that irradiate this main reflecting mirror. Among the systems, the primary radiator system in the high frequency band is arranged at the focal position of each partial mirror surface, and the primary radiator system in the lowest frequency band is placed at the focal position of each partial mirror surface.
It is important to note that the secondary radiator system is disposed at a position that is unevenly distributed from the focal point position of each partial mirror surface.

[Explanation based on examples]

Next, embodiments of the present invention will be described in detail based on the drawings.

FIG. 2 is a central vertical sectional view of the antenna according to the first embodiment of the present invention, and FIG. 3 is a front view of the main reflecting mirror of the antenna. In FIGS. 2 and 3, the main reflecting mirror 1' is constructed by combining partial mirror surfaces 2 and 3, each of which is a part of a paraboloid of revolution. The respective focal points F2 and F3 of the partial mirror surfaces 2 and 3 are located at different positions from each other, and the primary radiators 10 and 11 in the high frequency band are arranged at the focal points F2 and F3, respectively. This primary radiator 10 mainly irradiates the partial mirror surface 3 , and the primary radiator 11 mainly irradiates the partial mirror surface 2 . Each rotation center axis Z2 of this partial mirror surface 2.3,
Z3 is configured to be inclined at angles θ2 and θ3 in opposite directions with respect to the reference axis Z, respectively.

In an antenna with such a configuration, a radio wave from a spherical wave source radiated from the focal point F3 is reflected by the partial mirror surface 3 and then radiated as a plane wave traveling in the Z3 axis direction, for example, as the path is indicated by a broken line 20. .

My colleague told me that the radio waves from the spherical wave source emitted from the focal point F2 are reflected by the partial mirror surface 2 and then emitted as plane waves that travel in a direction parallel to the Z2 axis, as shown by the broken line 21.

Here, the primary radiator system 10 includes a plurality of primary radiators and a power distributor or a power combiner, and furthermore, the cross-sectional shape of the radiation beam after being reflected by the partial mirror surface 3 has a special shape, for example, approximately The primary radiator system 11 is configured to have an elliptical shape.
Assuming that is a normal conical horn, the radiation waves radiated from the partial mirror surfaces 2 and 3 are shown on the observation sphere as equal gain diagrams as shown by solid lines 31 and 30 in FIG. 4, respectively.

In the figure, points p, pg, and ps are respectively on axis 7. ,
Z! , Zs and the observation sphere, the vertical axis 40 represents the vertical angle, and the horizontal axis 41 represents the horizontal angle.

In the figure, the magnitudes of the equal gain lines 30 and 31 and the values of the equal gain lines differ depending on the sizes of the partial mirror surfaces 3 and 2 and the used frequency bands of the primary radiator systems 10 and 11, but they are shown in FIG. In the example shown, the aperture diameter of the entire main reflecting mirror 1' is approximately 2 m, the aperture diameter of the partial mirror surface 3 is approximately 1 m, and the primary radiator system 1
1 is free space wavelength power 7c! In the so-called microwave band of about rL, the value of the iso-original line is about 25 dB,
Also, the primary radiator system Lot'! , free space wavelength is 1cIr
In the so-called quasi-millimeter wave band of approximately L, the value of the isogain line is approximately 3.
Assuming 3 dB (・ru.

The above can be inferred from the fact that, in general, the antenna beam width (i) is proportional to the ratio of the free space wavelength λ to the antenna aperture diameter, and conversely, the antenna gain is proportional to Vλ.

Therefore, the partial mirror surfaces 2 and 3 allow beams in two frequency bands to be selected independently.

However, if, for example, it is desired to radiate a beam in a third, lower frequency band near point P in FIG. Separately arranging the primary radiator thread of the third frequency band near F2 or focal point F3 is as follows:
This is also physically difficult because the dimensions of the secondary radiator system are approximately proportional to the free space wavelength.

In order to improve this point, in this embodiment, the partial mirror surfaces 2 and 3 also utilize the wide beam width to emit the third primary radiation in the lowest frequency band between the focal points F2 and F3. By irradiating the entire main reflecting mirror 1' with the primary radiator 12, equal gain lines as shown by the broken line 32 in FIG. 4 are obtained. In general, a spherical wave arriving from a position unevenly distributed from the focal point is reflected by a rotating parabolic mirror and then radiated as a substantially plane wave-like wave that travels in a direction forming a certain angle with respect to the central axis of rotation. The angle of inclination from the center axis of rotation is determined as a value proportional to the ratio of the amount of uneven distribution from the focal point to the focal length.

Therefore, among the spherical waves emitted from the primary radiator system 12 shown in FIG. Similarly, the reflected wave from the partially mirrored surface 3 is emitted in a direction with an angle of 02 or less, and the reflected wave is radiated in a direction where the inclination angle θ6 from the Z axis is less than or equal to angle 03, as shown by the broken line 23, for example. The spherical wave radiated from the primary radiator system 12 becomes a radio wave radiated approximately in the Z-axis direction, and forms an equal gain diagram on the observation sphere as shown by the broken line 32 in FIG.

The equal gain diagram in Figure 4 shows that the free space wavelength is approximately 10 crIL.
It is assumed that the value of the equal gain line is z7dBi degree. The shape of the equal gain diagram indicated by the broken line 32 can be adjusted by the size of each partial mirror surface, focal length, angles θ2 and 03, the arrangement position of the primary radiator system 12, and the like. As explained above, the embodiment shown in FIG. 2 makes it possible to realize a multi-frequency band antenna that can be designed almost independently over three frequency bands.

FIG. 5 is a central vertical sectional view of an antenna according to a second embodiment of the present invention, and FIG. 6 is a front view of the main reflecting mirror of the antenna. In FIGS. 5 and 6, each reference numeral corresponds to each reference numeral in FIGS. 2 and 3, respectively.

The characteristic configuration of this embodiment is that a primary radiator system 10 for >tti (a-) is provided at the focal point F2 of the partial mirror surface 2, and a primary radiator system 10 for self-tracking is provided at the focal point F3 of the partial mirror surface 3. This is where the container 13 is placed.

Further, the central axis of rotation of the partial mirror surface 20 coincides with the reference axis Z, and the central axis of rotation of the partial mirror surface 3 is configured to be the axis Z3. 1 In such an antenna of tj configuration, the second
As is clear from the explanation of the figure, the radiation beams of the partial mirror surfaces 2 and 3 can be selected almost independently, and on the observation sphere, for example, as shown in FIG. 7, the equal gain diagram of the primary radiator system 10 is As shown by the solid line 30, the equal gain diagram of the primary radiator system 13 has a solid line 34 for the sum signal, four broken lines 33 for the difference number 48,
The thin line in the vertical direction is solid line 35, and the thin line in the horizontal direction is solid line 36.
, the zero point becomes the self-tracking equi-gain diagram of point P3, which is the intersection of the Z3 axis and the observation sphere.

Therefore, each beam for the communication signal and the self-tracking signal can be selected almost independently, and for example, when used in a satellite-mounted antenna, the installation position of the self-tracking ground station can be freely selected. There are advantages. Furthermore, if you want to radiate a beam in a lower frequency band near point P in FIG. 7 as in the case of the first embodiment, use a primary radiator system in a lower frequency band as in the first embodiment. By placing it between the focal points F2 and F3 and irradiating the entire main reflector 1',
An equal gain diagram as shown by the solid line 37 in FIG. 147 can be realized.

In addition, in the above explanation, an example was shown in which a radiator system composed of four horns is used as the primary radiator system for self-tracking, but other methods such as a method using a higher-order configuration can also be applied. .

Further, in the above description, the case where there are two partial mirror surfaces has been described, but the present invention can also be applied to a case where the number of partial mirror surfaces is three or more.

Further, for convenience of explanation, the antenna was treated as a transmitting antenna, but due to the reciprocity of the antenna, it can also be applied to a receiving antenna. Therefore, "
The terms ``irradiation'' and ``radiation'' do not limit the invention to transmitting antennas.

〔Effect of the invention〕

As explained above, according to the present invention, a main reflecting mirror is constructed by combining a plurality of partial mirror surfaces so that the focal positions are different from each other, and primary radiation in a high frequency band is emitted at the focal position of each partial mirror surface. By arranging the primary radiator system with the lowest frequency band at a position unevenly distributed from the focal point of each partial mirror surface and irradiating the entire main reflecting mirror, Correspondingly, almost independent beams can be combined, and a plurality of primary radiator systems can be physically easily arranged, which is an excellent advantage. For example, there are restrictions on the overall dimensions of the antenna,
Moreover, if used in satellite antennas that often use multiple frequency bands, great effects can be achieved.

[Brief explanation of the drawing]

FIG. 1 is a side view of a conventional parabolic antenna. FIG. 2 is a central vertical sectional view of the antenna according to the first embodiment of the present invention. Figure 3 is a front view of the main reflecting mirror. FIG. 4 is a radiation characteristic diagram of the antenna according to the first embodiment of the present invention. FIG. 5 is a central vertical sectional view of an antenna according to a second embodiment of the present invention. Figure 6 is a front view of the main reflecting mirror. FIG. 7 is a radiation characteristic diagram of the antenna according to the second embodiment of the present invention. 1.1'... Main reflecting mirror, 2.3... Partial mirror surface, 10
．． 11.12.13...Primary radiator system. Patent applicant representative Patent attorney Nao Takashi IdeFigure 1Figure 2Figure 3Figure 4Figure 5Figure 6

Claims (1)

[Claims] (1) One main reflecting mirror and this main reflecting mirror directly or one
A multi-frequency band shared antenna comprising a plurality of primary radiator systems that emit radiation through at least one sub-reflector, and configured so that each of the primary radiator systems can separately transmit and receive q=beams. In the main reflecting mirror, a plurality of partial mirror surfaces formed by a part of a paraboloid of revolution are combined so that their respective focal positions (white) are at different positions, and the plurality of primary radiator systems A primary radiator system that emits radio waves in a higher frequency band is disposed at a focal position of a specific partial mirror surface of the plurality of partial mirror surfaces, so as to irradiate a specific partial mirror surface among the plurality of partial mirror surfaces. Among the primary radiator systems, the primary radiator system that emits a low frequency band radio wave is arranged at a position unevenly distributed from the total focal position of the plurality of partial mirror surfaces so as to irradiate almost the entirety of the main reflecting mirror. An antenna that can be used for multiple frequency bands.