JP3810828B2 - Primary radiator - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a primary radiator configured to receive circularly polarized radio waves.
[0002]
[Prior art]
A conventional primary radiator of this type includes a receiving member for receiving the circularly polarized radio wave in a main body having an opening for receiving the circularly polarized radio wave (for example, Japanese Patent Laid-Open No. Hei 3). -220901).
The receiving member for receiving circularly polarized radio waves disclosed in this publication is composed of a well-known plate-like phase difference plate, similar to the well-known primary radiator for circularly polarized wave reception. It is composed of a phase circuit portion and an excitation probe arranged at a position capable of receiving a signal related to a circularly polarized radio wave.
[0003]
In the case of the above configuration, for example, in the situation where only right-handed circularly polarized radio waves are transmitted as in the present Japan, the right-handed circularly polarized radio wave is received from the opening, The receiving member can receive without any trouble. Also, for example, in the situation where only left-handed circularly polarized radio waves are transmitted as in South Korea, the left-handed circularly polarized radio waves can be received from the opening and received by the receiving member without any trouble. .
[0004]
[Problems to be solved by the invention]
However, the primary radiator with the above configuration has low cross-polarization discrimination, so not only right-handed circularly polarized waves but also left-handed circularly polarized waves are sent together in Japan in areas close to Korea. In this case, while receiving a right-handed circularly polarized radio wave, a part of the left-handed circularly polarized radio wave is also received by the same receiving member as described above, and both radio waves may not be discriminated and may cause interference. There is a problem that there is.
[0005]
The primary radiator of the present invention is provided in order to solve the problems (technical problems) of the prior art.
The first purpose is that even if a right-handed circularly polarized radio wave and a left-handed circularly polarized radio wave are sent together, they can be accurately discriminated with a high degree of cross polarization discrimination, and the desired to provide a primary radiator to be able to receive radio waves properly.
Other objects and advantages will be readily apparent from the drawings and the following description associated therewith.
[0006]
[Means for Solving the Problems]
The primary radiator according to the present invention includes a 12 GHz band right-hand circularly polarized radio wave and a left-hand circularly polarized radio wave having an opening for receiving both circularly polarized radio waves. In a primary radiator having a receiving member for receiving radio waves of both circular polarizations,
In the center of the opening, the diameter of the opening is approximately the same so as to increase the cross-polarization discrimination between the circularly polarized radio wave and the left circularly polarized radio wave. A dielectric having a quarter diameter and an odd multiple of a quarter of the number obtained by multiplying the wavelength of the radio wave introduced from the opening into the main body by the wavelength shortening rate of the dielectric; These are provided in a state where they are located only in the central part at intervals from the periphery of the opening, and are fixed in the central part.
[0007]
[Action]
The dielectric provided at the center of the opening increases the cross polarization discrimination of the primary radiator. A high degree of cross-polarization discrimination makes it possible to accurately discriminate between incoming right-handed and left-handed circularly-polarized radio waves, and enables reception of only target-polarized radio waves.
[0008]
【Example】
Hereinafter, drawings showing examples of the present application will be described. 1 and 2, A indicates the main body of the primary radiator 1 in the receiving antenna for receiving radio waves in the 12 GHz band, which is formed of a material having good conductivity, such as aluminum die casting, and denoted by reference numerals 2 to 7. It has a well-known configuration. That is, reference numeral 2 denotes a circular waveguide for introducing radio waves, and a well-known receiving member for receiving, for example, when a right-handed circularly polarized radio wave is introduced is provided at the back. Other examples of the receiving member include a receiving member for receiving when a left-handed circularly polarized radio wave is introduced, or a right-handed and left-handed circularly polarized radio wave is introduced. Two sets of receiving members may be used for receiving both of them individually. Reference numeral 3 denotes a horn provided at one end of the circular waveguide 2 on the radio wave introduction side, and the tip of the horn 3 is an opening 4 for receiving radio waves. The diameter of the opening 4 is, for example, 31 mm. Reference numeral 6 denotes a known corrugated choke provided around the opening 4, and the depth D1 of the groove is, for example, 6 mm. Reference numeral 7 denotes a cap mounting portion which is configured with an outer peripheral surface of the corrugated choke 6.
[0009]
Next, B shows a cap attached to the opening 4 in the primary radiator 1 for dust-proofing and waterproofing, and has a low relative dielectric constant (for example, about 2 to 3) and good radio wave transmission. It is made of a material having high weather resistance and easy to mold, for example, a synthetic resin material such as AES. Reference numeral 11 denotes an enclosing portion for enclosing the opening 4 in the cap B, and is constituted by a front wall 12 facing the opening 4. Reference numeral 14 denotes a fixing portion of the cap B with respect to the main body A, which is adhered to the cap mounting portion 7 in a watertight manner, for example, with an adhesive. The thickness T1 of the front wall 12 in the cap B is an allowable value (for example, 1 dB) for a loss given to transmission of radio waves (for BS or CS satellite broadcasting) in a 12 GHz band (11 to 12.7 GHz) to be received. In order to satisfy the following conditions, the thickness of the cap B is not more than 1/16 of the wavelength of the radio wave, and the required mechanical strength as the cap B is obtained. For example, the thickness is 0.8 mm, but may be about 1 mm. The fastening portion 14 is also formed with the same thickness as the front wall 12.
[0010]
Next, reference numeral 15 denotes a dielectric for improving the cross polarization discrimination, and its diameter D2 is approximately a quarter of the diameter of the opening 4 and is, for example, 8 mm. However, as described later, it may be slightly larger (for example, 9 mm) or slightly smaller (for example, 7 mm) as long as a predetermined standard value regarding the cross polarization discrimination degree can be cleared. The length L1 is preferably an odd multiple of approximately one quarter of the number obtained by multiplying the wavelength of the radio wave introduced from the opening 4 into the main body A by the wavelength shortening rate of the dielectric 15. The wavelength of the radio wave introduced into the main body A from the opening 4 is a wavelength at a place where the dielectric 15 is provided. For example, in this example where the dielectric 15 is provided in the horn 3, the horn 3 is provided. In-tube wavelength. In this embodiment, the length L1 is 35 to 0.63 because the guide wavelength is about 35 mm and the dielectric constant of the dielectric 15 is about 2.5 and the wavelength shortening ratio is 0.63. The length L1 is set to 5.5 mm by multiplying by about 22 mm, a quarter of which is 5.5 mm, and one time as an odd number. Other examples of length will be described later. The dielectric 15 is made of a material having a low relative dielectric constant (for example, about 2 to 3) and good radio wave permeability, such as a synthetic resin material such as AES. The dielectric 15 is placed in the center of the opening 4. For this purpose, the cap B is used as a support member and is formed integrally with the front wall 12 of the cap B. After forming the separate body, the dielectric 15 may be attached to the front wall 12 by adhesion. For example, in this example, the central portion of the opening 4 is in a state where the front end 15a is located in the opening 4 and the rear end 15b is located in the horn 3 behind the opening 4 in the front-rear direction. . However, for example, when a space is provided between the rear surface 12b of the front wall 12 and the opening 4, the rear end 15b is positioned at the opening 4, and the front end 15a is positioned forward of the opening 4. Or an intermediate portion in the front-rear direction is positioned in the opening 4, the front end 15 a is positioned in front of the opening 4, and the rear end 15 b is positioned in the horn 3 behind the opening 4. May be. Since the wavelength of the radio wave at each location differs according to the difference in position, the length L1 is preferably set to a length calculated from each wavelength. Regarding the lateral direction, in this example, the axis of the opening 4 and the axis of the dielectric 15 coincide with each other, but within a range in which a predetermined standard value regarding the cross polarization discrimination degree can be cleared as will be described later. It may be shifted slightly to the side. Reference numeral 16 denotes a hollow portion provided in the axial center portion of the dielectric 15 as required. The hollow portion 16 is used to prevent the resin material from sinking at the portion indicated by reference numeral 12c on the front surface 12a of the front wall 12 when the cap B and the dielectric 15 are integrally manufactured by molding a synthetic resin material. belongs to. The presence of the hollow portion 16 does not affect the function of the dielectric 15.
[0011]
In the above configuration, for example, a right-handed circularly polarized radio wave arriving from the front of the primary radiator 1 (left side in FIG. 1) in the use state is transmitted through the front wall 12 of the cap B and opened. It enters the horn 3 from the section 4 and further proceeds into the circular waveguide 2 and is received by the receiving member at the back. In this case, as a matter of course, the position of the excitation probe in the receiving member is arranged at a position where a signal related to right-handed circular polarization can be received. When the radio wave passes through the front wall 12 of the cap B and travels from the opening 4 to the horn 3, the front wall 12 is formed thin as described above, so that the loss of radio wave transmission is small.
[0012]
On the other hand, when circularly polarized radio waves s husband right- and left-handed from the front arrives together, since the opening 4 dielectric 15 for cross polarization discrimination is improved are provided, of course The excitation probe placed at a position where it can receive signals related to right-handed circularly polarized waves, the signals related to left-handed circularly polarized waves are virtually unaffected, and both radio waves are accurately discriminated (selected). Depending on the receiving member, only the desired right-handed circularly polarized radio wave can be properly received .
Contrary to the above case, the excitation probe arranged at a position where the signal related to the left-handed circularly polarized wave can be received is substantially the same as FIG. The two radio waves are discriminated.
[0013]
Next, the state of improvement of the cross polarization discrimination will be described with reference to FIG. 3 showing the results obtained by experiments. FIG. 3 shows the production of a number of primary radiators having dielectrics 15 having different lengths L1, and a 12.2 GHz main polarization (for example, right-handed rotation) for a parabolic antenna having each of them. Under the situation where radio waves of circular polarization and cross polarization (for example, left-handed circular polarization) arrive, both the amplitude level of the main polarization and the amplitude level of the cross polarization received are measured. The cross polarization discrimination degree is calculated from the values obtained by the above-described calculation method using a well-known calculation method, and the calculation result is plotted on a graph. The measurement was performed using a 45 cm parabolic antenna and an antenna measurement system manufactured by NSI. In FIG. 3, the horizontal line with a cross polarization discrimination of 20 dB is a first standard value, for example, a standard value defined by the Japan Electronic Machinery Manufacturers Association, and the 25 dB horizontal line is defined by a second standard value, for example, the World Radio Communications Central Office meeting. It is a standard value.
[0014]
When the length L1 of the dielectric 15 is λ / 4 (5.5 mm), which is a quarter of the number obtained by multiplying the wavelength by the wavelength shortening rate (indicated by λ in FIG. 3), the cross polarization identification The degree is about 35 dB, and both the above-mentioned standard values can be sufficiently cleared. In the range of λ / 8 to 3λ / 8 (2.75 to 8.25 mm), which is shown as a range of almost a quarter, the first standard value can be cleared, and the range of about 3λ / 16 to 5λ / 16. In (4.13 to 6.88 mm), not only the first standard value but also the second standard value can be cleared. Also, in the case of 3λ / 4 (16.5 mm), which is 3 times as shown in another example of the odd multiple, the cross polarization discrimination degree is about 30 dB. Both are clear enough. In the range of 5λ / 8 to 7λ / 8 (13.75 to 19.25 mm), which is shown as a range that is approximately three times one quarter, the first standard value can be cleared, and about 11λ / 16 to 13λ / In the range of 16 (15.13 to 17.8 mm), not only the first standard value but also the second standard value can be cleared. Therefore, the length L1 is preferably determined from the above range so that the required standard value can be cleared.
[0015]
Next, FIG. 4 shows a different example of means for providing the dielectric 15e in the central portion of the opening 4e, and shows an example in which the dielectric 15e is supported by the support member 17. FIG. The support member 17 is preferably formed of a resin material having a low relative dielectric constant so that there is no adverse effect on the radio waves entering the horn 3e from the front of the opening 4e through the opening 4e. One end and the other end of the support member 17 are fixed to the inner peripheral surface of the opening 4e and the outer peripheral surface of the dielectric 15e, respectively, with an adhesive, for example. However, the support member 17 may be fixed to the dielectric 15e by integrally forming both. In addition, the part which is considered functionally the same or equivalent to the thing of the previous figure, and overlaps description is attached | subjected to the code | symbol same as the previous figure, and the overlapping description is abbreviate | omitted.
[0016]
【The invention's effect】
As described above, in the present invention, at the central portion of the opening 4, the diameter of the opening 4 is approximately one-fourth the diameter of the radio wave introduced from the opening 4 due to the dielectric 15. The dielectric 15 having a length that is an odd multiple of approximately one-fourth of the number multiplied by the wavelength shortening rate is located only in the central portion at a distance from the periphery of the opening, and is fixed. since the let provided in, high cross polarization discrimination as is clear from FIG. 3 is Ru obtained.
Therefore, when receiving using a primary radiator having a function of receiving right-handed circularly polarized radio waves, even if left-handed circularly polarized radio waves are sent together, in the present invention, As described above, it is possible to accurately discriminate both of them with a high degree of cross polarization discrimination, and it is possible to appropriately receive a desired circularly polarized radio wave.
[Brief description of the drawings]
FIG. 1 is a partially broken side view of a primary radiator.
FIG. 2 is a rear view of a cap and a dielectric.
FIG. 3 is a graph showing the relationship between dielectric length and cross polarization discrimination.
FIG. 4 is a perspective view showing a different example of dielectric support means.
[Explanation of symbols]
A Body 4 Opening
15 Dielectric

Claims (1)

A 12 GHz band right-handed circularly polarized radio wave and left-handed circularly polarized radio wave are received in the main body with an opening for receiving both circularly polarized radio waves. In a primary radiator comprising a receiving member for
In the center of the opening, the diameter of the opening is approximately the same so as to increase the cross-polarization distinction between the right-handed circularly polarized radio wave and the left-handed circularly polarized radio wave. A dielectric having a quarter diameter and an odd multiple of a quarter of the number obtained by multiplying the wavelength of the radio wave introduced into the main body from the opening by the wavelength shortening rate of the dielectric; A primary radiator characterized in that the primary radiator is provided in a state of being located only in the central portion at a distance from the periphery of the opening and being fixed in the central portion.

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