JP3362292B2 - Primary radiator - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a parabolic antenna, which receives a circularly polarized radio wave reflected and converged by a parabolic reflector and converts it into a linearly polarized wave. And a primary radiator used to convert the signal into a coaxial mode. 2. Description of the Related Art A conventional primary radiator is constructed, for example, as shown in FIG. That is, in order to accept the circularly polarized radio wave reflected and converged by the parabolic reflector,
An electromagnetic horn 11 having an aperture diameter corresponding to the aperture angle of the parabolic reflector and a length of 1/4 of the wavelength of the radio wave to be received.
f, a matching waveguide 17f for performing impedance matching between the electromagnetic horn 11f and the coaxial waveguide converter 22f, and a coaxial waveguide for converting a radio wave of the waveguide mode into a signal of the coaxial mode. The tube converter 22f is sequentially connected, and the matching waveguide 17f is connected.
Inside, a phase difference plate 30f for converting a circularly polarized radio wave into a linearly polarized radio wave is provided. In such a primary radiator, an electromagnetic horn 11
Since f has the above-described size, the circularly polarized radio wave reflected and converged by the parabolic reflector can be smoothly received, and the received radio wave passes through the matching waveguide 17f. This makes it possible to convert the signal into linearly polarized radio waves by the phase difference plate 30f and to send it to the coaxial waveguide converter 22f while passing through the matching waveguide 17f. The device 22f can efficiently obtain a coaxial mode signal. However, in the above-mentioned primary radiator, since the phase difference plate 30f is provided in the matching waveguide, the length of the matching waveguide 17f is reduced by the electromagnetic horn 11f. In addition to the length required for impedance matching with the coaxial waveguide converter 22f and the coaxial waveguide converter 22f, a length L2f sufficient to accommodate the phase difference plate 30f is required. This has a problem that the length of the entire primary radiator 6f is increased by the length necessary to accommodate the phase difference plate 30f in the matching waveguide 17f. Primary radiator
If 6f is so long, there is a problem in the parabolic antenna that the structure for supporting the primary radiator is complicated (it requires a structurally strong one). In addition, if the primary radiator is large as described above, the wind hit during use of the parabolic antenna becomes strong, and the arm supporting the primary radiator shakes in a strong wind, and the primary radiator often deviates from the focal point of the reflector. There was a problem that the received image was disturbed. The present invention has been made to solve the above-mentioned problems (technical problems) of the prior art, and provides a primary radiator having a small external shape while maintaining good electrical performance. It is intended to be. The primary radiator according to the present invention has an aperture corresponding to the opening angle of the parabolic reflector in order to receive the circularly polarized radio wave reflected and converged by the parabolic reflector. Caliber and 1/4 of the wavelength of the radio wave to be accepted
An electromagnetic horn having a length, a matching waveguide for performing impedance matching between the electromagnetic horn and the coaxial waveguide converter, and converting a waveguide mode radio wave into a coaxial mode signal. Primary radiation with a phase difference plate for converting a circularly polarized wave into a linearly polarized wave in the matching waveguide. In the device, the phase difference plate is provided with a first matching portion for performing impedance matching by being positioned in the electromagnetic horn, and a second matching portion for performing impedance matching by being positioned in the matching waveguide 17. ,
A circular-to-linear converter for converting a circularly polarized wave into a linearly polarized wave, which is located between the first matching portion and the second matching portion. When the phase difference plate is mounted, the position is determined such that the second matching portion is located in the matching waveguide, and the first matching portion is protruded from the matching waveguide in the electromagnetic horn. Both sides of a portion of the phase difference plate located in the matching waveguide are fixed to an inner surface of the matching waveguide with an adhesive to support the phase difference plate. The circularly polarized radio wave reflected and converged by the parabolic reflector is received by the electromagnetic horn. The received radio wave is transmitted to the coaxial waveguide converter with good matching by passing through the matching waveguide. In the process, the received circularly polarized radio waves are converted from circularly polarized waves into linearly polarized waves by the phase difference plate. The linearly polarized radio wave reaching the coaxial waveguide converter is converted into a coaxial mode signal in the coaxial waveguide converter. An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 showing the usage state of the parabolic antenna will be described. 1 to 9 show a well-known configuration, 1 is a column, 2 is a parabolic antenna, 3 is a mounting tool for mounting the parabolic antenna 2 to the column 1 so that the elevation and azimuth angles can be freely adjusted. Parabolic reflectors 5 and 5 in the parabolic antenna 2 are supporting arms for supporting the primary radiator 6 at the focal position of the reflector 4 and for supporting the primary radiator 6 when the converter 7 is attached. 8 indicates the presence of a cap, such as a resin cap, covering the opening of the primary radiator 6 to prevent rainwater from entering the opening, and 9 indicates the outer surface of the primary radiator 6 and the converter 7 for waterproofing. Cover, for example, a resin cover. The primary radiator 6 is for receiving a circularly polarized radio wave reflected by the reflecting mirror and converging toward its focal position and converting it into a coaxial mode signal. 2 to FIG. Numeral 11 denotes an electromagnetic horn for receiving the circularly polarized radio wave, and an aperture diameter D1 corresponding to the aperture angle α of the parabolic reflector 4 for uniformly receiving the excitation distribution on the mirror surface of the parabolic reflector 4. In addition, in order to perform good impedance matching between the free space and the waveguide (the matching waveguide described below), the wavelength of the radio wave to be received in the internal receiving space 13 (in the receiving space 13). It has a length L1 that is １ ／ of the wavelength λg ′).
The aperture diameter D1 is 28.6 mm and the length L1 is 9.4 mm in the case of a primary radiator for receiving a 12 GHz radio wave of a broadcasting satellite, for example. The inner peripheral surface 12 of the electromagnetic horn 11 has a smooth tapered surface in order to perform the above impedance matching well. 14 indicates an open end of the electromagnetic horn 11,
The focal point F of the parabolic reflecting mirror 4 is set at the center of the parabolic reflector 4 in order to efficiently perform circular-linear polarization conversion by a phase difference plate described later. Reference numeral 15 denotes a corrugated choke for improving the directivity of a parabolic antenna. The number of the corrugated chokes 15 may be two or more. Reference numeral 17 denotes a matching waveguide for performing impedance matching between the electromagnetic horn 11 and a coaxial waveguide converter 22, which will be described later, and smoothly transmits a radio wave coming from the electromagnetic horn 11 to the next stage. The inner diameter D2 corresponding to the frequency of the radio wave for guiding, and the wavelength λg ′ for better impedance matching.
And a length L2 of １ ／ of the average value of the wavelength λg in the matching space 19 inside the matching waveguide 17. Above inner diameter D2
Is, for example, 17.475 mm for the reception of the radio wave, and the length L2 is 10.4 mm. Reference numerals 20, 20 denote mounting grooves provided on a part of the inner peripheral surface 18 for mounting a retardation plate. next
Reference numeral 22 denotes a coaxial waveguide converter for converting a waveguide mode radio wave into a coaxial mode signal. Reference numeral 23 denotes a waveguide in the converter 22.For the above conversion, the rear end is closed by a short-circuit surface 24, an inner diameter D3 having the same size as the inner diameter D2, and an inner conversion space 25. It has a length L3 that is half the wavelength λg of the radio wave. The inside diameter D3 may be slightly smaller than the inside diameter D2, and the waveguide 23 may be tapered. The length L3 is, for example, 22.9 mm in the case of receiving the radio wave. 26 is a probe for extracting coaxial mode signals.
It is provided at a position where the distance L4 up to 24 is 1/4 of the wavelength λg. An end of the probe 26 outside the waveguide 23 is connected to an input end of the converter 7 for signal transmission. The probe 26 is preferably formed of a metal material having good conductivity, for example, brass in order to smoothly transmit a signal. Reference numeral 27 denotes a member for holding the probe 26, which is made of an insulating material to hold the probe 26 in an insulated state with respect to the waveguide 23. In order to operate as a coaxial line together with the probe 26, the member 27 is preferably made of a material having a small loss at the frequency handled by the primary radiator, for example, a member made of fluororesin. The electromagnetic horn 11, the matching waveguide 17, and the waveguide 23 in the converter 22 are preferably formed integrally to stabilize the mutual positional relationship. They are preferably formed of a material having good conductivity in order to improve the propagation of radio waves in the internal space. One example of these materials and forming methods is zinc die casting. Reference numeral 30 denotes a phase plate for converting circularly polarized radio waves into linearly polarized radio waves. Reference numeral 31 denotes a first matching portion for performing impedance matching between the electromagnetic horn 11 and the phase difference plate 30 in the phase difference plate 30, and a length L11 of the first matching portion for performing the matching operation is equal to that of the phase difference plate 30. When the relative dielectric constant is represented by εr, the length is obtained by multiplying ４ of the wavelength λg ′ by 1 / √ (εr). For example, when the relative permittivity εr is 10, it is 3 mm for receiving the radio wave. Numeral 32 denotes a circular-to-linear converter for converting circularly polarized waves into linearly polarized waves. The length L12 for the above-mentioned circular-to-linearly polarized wave conversion is reduced to 1/4 of the wavelength λg ', 1 / 、 The length is multiplied by {(εr) -1}. For example, the relative permittivity is 4.3 mm in the case of receiving the radio wave. Reference numeral 33 denotes a second matching portion for performing impedance matching between the phase difference plate 30 and the matching waveguide 17, which is shorter than the length of the combined portion of the first matching portion 31 and the circular-to-linear converter 32. 1/4 of the wavelength λg to form
Is multiplied by 1 / √ (εr). 2. For example, in the case of the above-mentioned relative permittivity and the above-mentioned radio wave reception
6 mm. The phase difference plate 30 as described above has a portion less than half of its length in the matching waveguide 17 as clearly shown in FIG. A portion within the length of the electromagnetic horn 11 is located in the electromagnetic horn 11. For example, in this example, by forming the length of the combined portion of the first matching portion 31 and the circular-linear conversion portion 32 shorter than the length L1 of the electromagnetic horn 11 and positioning it in the electromagnetic horn 11, As is clear from FIG. 3, the first matching portion 31 is located in the electromagnetic horn 13 so as to protrude from the matching waveguide 17. The second matching section 33 is located in the matching waveguide 17. Further, both sides of a portion of the phase difference plate 30 shown in FIG. 3 which is located in the matching waveguide 17 are fitted into the mounting grooves 20 as shown in the drawing in order to fix the both sides. It is fixed by a fixing means, for example, an adhesive. The boundary between the circular direct conversion unit 32 and the second matching unit 33 may be closer to the side inside the electromagnetic horn 11 or closer to the side inside the matching waveguide 17 than in this example. The first matching portion 31 and the second matching portion 33 may have a tapered shape or a shape having a cut. The phase difference plate 30 is formed of a material having a high dielectric constant, for example, a material having a relative dielectric constant εr of 6 or more, in order to enable the electromagnetic horn 11 and the matching waveguide 17 to be arranged in the above relationship. . One example is formed of a material obtained by mixing a ceramic with a polyphenylene oxide resin, and has a relative dielectric constant of 10.45. As other materials, a ceramic plate or a resin plate mixed with a powder of ceramic or alumina can be used. The thickness of the phase difference plate 30 is preferably set to a small value, for example, 1.5 mm or less in order to reduce the axial ratio, which is one of the electrical performances of the primary radiator, to, for example, 1 dB or less. It is preferable to use a material having a large dielectric constant. In the case of a material obtained by mixing a ceramic with a polyphenylene oxide resin, the thickness is, for example, 0.78 mm. The angle θ between the phase difference plate 30 and the probe 26 shown in FIG. 2 is set to, for example, 45 ° in order to efficiently extract the converted linearly polarized radio wave to the probe 26 in the coaxial mode. In the above configuration, reference numeral 41 in FIG.
As shown by a circle, a circularly polarized radio wave arriving from a transmission source of a radio wave, for example, a broadcasting satellite is reflected by the parabolic reflector 4 and converged toward its focal point F. The converged radio wave enters the receiving space 13 of the electromagnetic horn 11, and passes therethrough to the matching space 19 in the waveguide mode. In the process in which the circularly polarized radio wave reaches the matching space 19 from the receiving space 13, the radio wave is converted by the phase difference plate 30 into a linearly polarized radio wave. In this case, since the light reaches the circular-to-linear converter 32 via the first matching part 31 and further reaches the matching space 19 via the second matching part 33, the polarization conversion is smooth and the impedance matching is good. It is. The linearly polarized radio wave travels from the matching space 19 to the conversion space 25, where the conversion from the waveguide mode to the coaxial mode is performed as is well known, and the coaxial mode signal is probed.
It is taken out to 26. The signal reaches the converter 7, where it is frequency-converted and transmitted from an output terminal 7a. In the case of performing reception as described above, since the relative dielectric constant of the phase difference plate 30 is high, its thickness can be reduced. Thus, the circular-linear polarization conversion is performed efficiently. For this reason, the axial ratio is improved, and in the case of a circularly polarized radio wave in the opposite direction, for example, satellite broadcasting, it is possible to reduce the possibility of interference from Korean satellite broadcasting waves. Further, as described above, the phase difference plate 30 is shortened (L
If the thickness can be reduced by adding 11 to L13), the ratio of the dielectric (the phase difference plate 30) in the waveguide is reduced, and the transmission loss of the radio wave by the dielectric can be reduced. Therefore, when used for a parabolic antenna, antenna efficiency and antenna noise can be reduced. Further, since the phase difference plate 30 is thin, the reflected wave by the phase difference plate 30 is suppressed, and the VSWR is improved. As described above, according to the present invention, when a circularly polarized radio wave reflected and converged by the parabolic reflector 4 arrives, the electromagnetic horn 11 causes the aperture of the parabolic reflector 4 to open. Since it has an aperture diameter D1 corresponding to the angle α and a length of 1/4 of the wavelength λg 'of the received radio wave, the above-mentioned circularly polarized radio wave can be smoothly received, and the received radio wave is used for matching. By passing through the waveguide 17, good matching is obtained, and the wave plate is smoothly converted into a linearly polarized wave by the phase difference plate 30 composed of the first matching portion 31, the circular-to-linear conversion portion 32, and the second matching portion 33, and is coaxial. The signal can be sent to the waveguide converter 22, and the coaxial waveguide converter 22 has an effect that a signal in the coaxial mode can be efficiently obtained. Further, in the primary radiator 6 of the present invention, the phase difference plate 30 is located in the electromagnetic horn 11 to perform impedance matching, and the matching waveguide 17 is provided. And a second matching section 33 for performing impedance matching by being located inside the first matching section 31 and the second matching section 33 for converting circularly polarized waves into linearly polarized waves. The phase difference plate 30 is mounted on the matching waveguide 17 when the second matching portion 33 is located in the matching waveguide 17 and the electromagnetic horn 13 is located in the electromagnetic horn 13. The first matching portion 31 is positioned so as to protrude from the matching waveguide 17, and both sides of a portion of the phase difference plate 30 located inside the matching waveguide 17 are aligned with the matching waveguide 17. Is fixed to the inner surface of the base plate with an adhesive, the second matching section 33 is
In only a small part, the length of the matching waveguide 17 becomes short, and even if the matching waveguide 17 is short, it can be sufficiently accommodated therein, and the matching waveguide 17 is connected between the electromagnetic horn 11 and the coaxial waveguide converter 22. It has the feature that it can be as short as required for the matching action, and is effective in shortening the primary radiator 6. In addition, in the case of fixing both sides of the portion of the phase difference plate 30 located in the matching waveguide 17 to the inner surface of the matching waveguide with an adhesive, the portions to be bonded are:
The first matching portion 31 projects from the matching waveguide 17,
The remaining portion of the phase difference plate 30 located in the matching waveguide 17 is extremely short and small. Therefore, there is an advantage that the amount of the adhesive used for bonding there is extremely small. 3 and 4, the portion to be bonded is on the side of the opening of the tip end of the matching waveguide 17, and the opening is formed by the electromagnetic horn 11 which is spread like a trumpet.
, The fingertip of the work clothes has a feature that the work can be performed as close as possible to a position close to the adhesive portion. This enables uniform and accurate bonding using a small amount of adhesive, and has the effect of increasing the reliability of bonding.In addition, the amount of the dielectric adhesive is small and can be evenly distributed. And the dielectric constant becomes uniform, the passage loss therethrough is small, and the adverse effect on the cross polarization characteristics is reduced. As for the transmission loss of radio waves, the ratio of the dielectric (phase plate 30) in the matching waveguide 17 is small.
There is also an effect that the transmission loss of radio waves by the dielectric can be reduced. The phase difference plate for the matching waveguide 17
Attachment of 30 determines the position so that the first matching portion 31 protrudes from the matching waveguide 17 in the electromagnetic horn 13,
Since both sides of the remaining portion of the retardation plate 30 located in the matching waveguide 17 are fixed to the inner surface of the matching waveguide with an adhesive, the phase difference plate 30 is attached to the opening of the primary radiator 6. There is a feature that the fixing work can be performed regardless of the presence or absence of the cap. This means that the thickness of the cap attached to the opening has recently been extremely thin and formed in the form of a film in order to reduce transmission loss of radio waves, but in the present invention, prior to the attachment of the cap, Since the fixing work of the retardation plate 30 can be performed, there is an effect that the cap is not damaged. Further, by configuring both sides of the remaining portion of the phase difference plate 30 located in the matching waveguide 17 on the inner surface of the matching waveguide with an adhesive to support the phase difference plate, 30 is characterized in that even if the cap attached to the opening vibrates violently due to severe wind and rain, it can be maintained in a stable state without being affected by the vibration. This allows the retardation plate 30 to be formed thin (even if it is mechanically weakened), and the amount of dielectric material is reduced, so that the transmission loss of radio waves is reduced.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side view of a parabolic antenna. FIG. 2 is a front view of a primary radiator. FIG. 3 is a sectional view of the primary radiator taken along the line III-III in FIG. 2; FIG. 4 is a sectional view of the primary radiator taken along the line IV-IV in FIG. 2; FIG. 5 is a partially cutaway perspective view of a conventional primary radiator. [Description of Signs] 4 Parabolic reflector 6 Primary radiator 11 Electromagnetic horn 17 Waveguide for matching 22 Coaxial waveguide converter 30 Phase difference plate 31 First matching part 32 Circular-to-linear conversion part 33 Second matching part

Claims (1)

(57) [Claims 1] In order to receive a circularly polarized radio wave reflected and converged by a parabolic reflector, an aperture diameter corresponding to the opening angle of the parabolic reflector and the received radio wave An electromagnetic horn having a length of 1/4 of the wavelength, a matching waveguide for performing impedance matching between the electromagnetic horn and the coaxial waveguide converter, and a coaxial waveguide mode radio wave. A coaxial waveguide converter for converting to a mode signal is connected in series,
In the primary radiator, which has a phase difference plate for converting a circularly polarized wave into a linearly polarized wave in the matching waveguide, the phase difference plate is located in an electromagnetic horn. A first matching section for performing impedance matching, a second matching section for performing impedance matching by being positioned in the matching waveguide 17, and a position between the first matching section and the second matching section. And a circular-to-linear converter for converting a circularly polarized wave into a linearly polarized wave. The mounting of the phase difference plate on the matching waveguide is performed by inserting the second wave into the matching waveguide. A matching portion is located, and the first matching portion is positioned in the electromagnetic horn so as to protrude from the matching waveguide, and both sides of a portion of the phase difference plate located in the matching waveguide are determined. It is characterized in that the above-mentioned retardation plate is supported by being fixed to the inner surface of the matching waveguide with an adhesive. The primary radiator to be marked.