JPH0770911B2 - Planar antenna - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a planar antenna used when a radio wave from a broadcasting satellite or communication hygiene is received by a ground station.

[Background Art] In recent years, SHF using a geostationary satellite that is stationary at 36000 km above the equator.
Band (12 GHz band) satellite broadcasting and satellite communication using multipurpose communication satellites have been put into practical use. Parabolic antennas are generally used as receiving antennas at ground stations in communications using these artificial satellites, but the antennas are large and complex in shape, and because they are susceptible to wind pressure There is a problem that the construction is troublesome and the cost is high. As a solution to this problem, a flat antenna that can be easily attached to a roof or wall and is easy to maintain has been receiving attention.

By the way, if two types of polarized waves having opposite polarization relations such as horizontally polarized wave and vertically polarized wave or left-handed circularly polarized wave and right-handed circularly polarized wave are used, each polarized wave is generated by using radio waves of the same frequency. Since it is possible to send different information for each wave, the use efficiency of radio waves can be improved. However, in the planar antenna, as shown in FIG. 8, for example, in 11.0 to 12.0 GHz, the reverse polarization component (shown in the lower part of FIG. 8) with respect to the main polarization component (shown in the upper part of FIG. 8) is −9 to −. It is about 20 dB, and there is a problem that unnecessary polarization components are not sufficiently suppressed.

[Object of the Invention] The present invention has been made in view of the above points, and an object thereof is to provide a planar antenna with improved cross polarization characteristics.

DISCLOSURE OF THE INVENTION (Structure) The planar antenna according to the present invention uses main polarized waves having mutually opposite polarization relations such as vertical polarized waves and horizontal polarized waves or left-handed circular polarized waves and right-handed circular polarized waves. Is formed on one antenna surface, and an unnecessary reverse polarization component included in the reception signal of one antenna unit is canceled by the main polarization component of the reception signal of the other antenna unit. A wave removing unit is provided, and an unnecessary reverse polarization component of a reception signal of one antenna unit is canceled by a main polarization component of a reception signal of the other antenna, so that an unnecessary polarization component is generated. Is included in the reception signal of the one antenna unit by changing the frequency characteristic of the main polarization component of the reception signal of the other antenna unit in the reception frequency region in the reception frequency region. Frequencies of unwanted reverse polarization components A filter circuit to match the characteristics, characterized by providing a combiner for combining the output signal of the received signal and the filter circuit of one of the antenna unit above.

That is, by providing the filter circuit as described above, unnecessary components can be removed over a wide frequency band and used in a wide band (for example, 11.0 to 12.0 GHz) as in the case of receiving satellite broadcast radio waves. Even in this case, unnecessary components can be removed without the need for adjustment according to the frequency.

(Principle) The principle of the present invention will be described with reference to FIGS. As shown in FIG. 2, two antenna parts 1a and 1b are formed on one antenna surface 1. Both antenna parts 1a, 1b are formed so that the main polarization components are polarizations having mutually opposite polarization relations, such as vertical polarization and horizontal polarization, or left-hand circular polarization and right-hand circular polarization. . For example, with patch antennas,
An antenna pattern 2a for horizontal polarization as shown in FIG. 3 (a) is formed on one antenna portion 1a, and an antenna pattern 2b for vertical polarization as shown in FIG. 3 (b) is formed on the other antenna portion 1b.
Or a left-handed circularly polarized antenna pattern 2c as shown in FIG. 3 (c) is formed on one antenna portion 1a and a right-handed antenna pattern as shown in FIG. 3 (d) is formed on the other antenna portion 1b. An antenna pattern 2d for polarized waves is formed. The area occupied by the antenna parts 1a and 1b on the antenna surface 1 is different. For example, as shown in FIG. 2 (a), the antenna surface 1 may be divided horizontally,
Alternatively, as shown in FIG. 2B, one antenna portion 1a may surround the other antenna portion 1b.
As shown in Fig. 1, the antenna part 1a with the larger area
The received signal received at is amplified by the preamplifier circuit 3 which is a low noise amplifier, and input to the combiner 7 (Wilkinson type combiner). The antenna part with the smaller area
The received signal received at 1b is amplified by the preamplifier circuit 4 which is a low noise amplifier, and then the phase shifter 5 which inverts the phase,
It is input to the combiner 7 via the attenuator 6 whose attenuation amount can be adjusted. That is, the combiner 7 combines the reception signals of both antenna units 1a and 1b, and cancels signals having opposite phases. The output of the synthesizer 7 is input to the low noise converter 8 and frequency-converted to a lower frequency.

Here, the first antenna unit 1a having the larger area receives the horizontal polarized wave as the main polarized wave component, and the second antenna unit 1b having the smaller area receives the vertical polarized wave as the main polarized wave component. Is set as follows. In this case, in the first antenna unit 1a, the vertical polarization component with respect to the horizontal polarization component is, for example, 99: 1, and in the second antenna unit 1b, the horizontal polarization component with respect to the vertical polarization component is 99 pairs, for example. It becomes 1. Therefore, the attenuator 6 is adjusted so that the second antenna unit
If the vertical polarization component of the reception signal of 1b is set to be substantially the same level as the vertical polarization component of the reception signal of the first antenna unit 1a and combined by the combiner 7, the vertical polarization components are almost canceled out, On the other hand, the horizontal polarization component of the received signal of the first antenna unit 1a is hardly affected, so that a very high cross polarization characteristic can be obtained. Moreover, since the area of both antenna parts 1a and 1b is changed and the area of the antenna part 1b which receives a vertical polarization component as a main polarization component is made small, most horizontal polarization components are output from the attenuator 6. First antenna section
The horizontal polarization component of the received signal of 1a is the second antenna section
It is hardly affected by the received signal of 1b. Even if the above method is used for circularly polarized waves, the same effect can be obtained.

(Embodiment 1) In this embodiment, as shown in FIG. 4, the second antenna unit 1b is used.
After being amplified by the preamplifier circuit 4, the output of (1) is passed through the filter circuit 9 before being input to the phase shifter 5.
The frequency of the reverse polarization component (the lower curve in FIG. 5; the upper curve in FIG. 5 represents the main polarization component) of the first antenna unit 1a as shown in FIG. Set appropriately according to the characteristics. That is, the output level of the filter circuit 9 corresponding to the main polarization component of the second antenna unit 1b is set to the same frequency characteristic as the reverse polarization component of the reception signal of the first antenna unit 1a. By doing so, the inverse deviation component can be almost completely canceled out in the entire reception frequency region by setting the attenuation amount of the attenuator 6 to a constant value regardless of the reception frequency. As in the present embodiment, the filter circuit 9 is provided and the filter circuit 8 corresponding to the main polarization component of the reception signal of the second antenna unit 1b is provided.
When the output level of is matched with the frequency characteristic of the reverse polarization component of the reception signal of the first antenna unit 1a, an unnecessary reverse polarization component is received from the reception signal of the first antenna unit 1a over a wide frequency band. It can be removed. That is, even when the plane antenna is used in a wide band such as when receiving satellite broadcast waves, unnecessary components can be removed without requiring adjustment according to the frequency.

(Embodiment 2) In the above embodiment, only one of the two types of polarization components having a reverse polarization relationship was taken out, but in the present embodiment, both polarization components can be taken out at the same time. It is the one. That is, the configuration of the second embodiment is symmetrically provided to both antenna units 1a and 1b, and as shown in FIG.
After being amplified by 3 and 4, they are input to the combiners 7a and 7b through the filter circuits 9a and 9b, the phase shifters 5a and 5b, and the attenuators 6a and 6b, respectively, and are combined with the reception signals of the other antenna units 1a and 1b. It has become so. Here, the antenna unit 1 together with the circuit unit
As for a and 1b, as shown in FIG. 7, both antenna parts 1
It is divided so that the areas of a and 1b are almost equal. According to this configuration, two different polarization components can be extracted at the same time, and both outputs do not include unnecessary reverse polarization components.

[Effects of the Invention] As described above, the present invention uses, as main polarizations, polarizations that are in opposite polarization relation to each other, such as vertical polarization and horizontal polarization, or left-hand circular polarization and right-hand circular polarization. An undesired polarization removing means, in which two antenna parts are formed on one antenna surface, and an unnecessary reverse polarization component included in the reception signal of one antenna part is canceled by the main polarization component of the reception signal of the other antenna part Is provided, which has the advantage that unnecessary polarization components can be positively removed and the cross polarization characteristics are greatly improved. In particular, the unnecessary wave removing means changes the frequency characteristic of the main polarization component of the reception signal of the other antenna section in the reception frequency region to eliminate unnecessary reverse polarization components included in the reception signal of the one antenna section. Since the filter circuit that matches the frequency characteristics and the synthesizer that synthesizes the reception signal of the one antenna unit and the output signal of the filter circuit are provided, unnecessary components can be removed over a wide frequency band. Even if it is used in a wide band (for example, 11.0 to 12.0 GHz) as in the case of receiving satellite broadcast waves, it is possible to remove unnecessary components without requiring adjustment according to the frequency. .

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing a basic configuration for explaining the principle of the present invention, FIG. 2 is a front view showing a configuration example of an antenna portion used in the same, and FIG. 3 is a front view showing an example of an antenna pattern used in the same as above. FIG. 4, FIG. 4 is a schematic configuration diagram showing a first embodiment of the present invention, FIG. 5 is an operation explanatory diagram of the same as above, FIG. 6 is a schematic configuration diagram showing a second embodiment of the present invention, and FIG. FIG. 8 is a front view showing a configuration example of the antenna section, and FIG. 8 is an operation explanatory view of a conventional example. 1 is an antenna surface, 1a and 1b are antenna parts, 3 and 4 are preamplifier circuits, 5 is a phase shifter, 6 is an attenuator, 7 is a combiner, 8 is a low noise converter, and 9 is a filter.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hiroo Inoue 1048, Kadoma, Kadoma, Osaka Prefecture Matsushita Electric Works Co., Ltd. (72) Nobuaki Miyaji, 1048, Kadoma, Kadoma City, Osaka Matsushita Electric Works, Ltd. (56) References JP-A-58-24248 (JP, A)

Claims (2)

[Claims] Claim: What is claimed is: 1. An antenna plane having two main antennas, which are polarizations having opposite polarization relations, such as vertical polarization and horizontal polarization, or left-hand circular polarization and right-hand circular polarization. Unnecessary in a planar antenna equipped with unnecessary polarization removing means that is formed above and cancels the unnecessary reverse polarization component contained in the reception signal of one antenna unit by the main polarization component of the reception signal of the other antenna unit The polarization removing means changes the frequency characteristic of the main polarization component of the reception signal of the other antenna unit in the reception frequency region to obtain the frequency characteristic of the unnecessary reverse polarization component included in the reception signal of the one antenna unit. 2. A planar antenna comprising: a filter circuit that matches the above condition; and a combiner that combines the reception signal of the one antenna unit and the output signal of the filter circuit. 2. A pair of the unnecessary polarized wave removing means are provided to remove unnecessary reverse polarized wave components of the reception signals of the other antenna units and take out the main polarized wave components of the respective antenna units. The planar antenna according to claim 1, wherein the planar antenna is formed.