JP2007329717A - Array power feed reflector antenna - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an array power feed reflector antenna capable of electrically compensating an attitude variation of a satellite, fitting errors of a reflector and a power feed part, and antenna pattern deformation caused the deformation of a reflector surface with a smaller circuit scale. <P>SOLUTION: The array power feed reflector antenna which operates at two or more frequencies (F1, F2) is characterized in that phase shift quantities (ϕ<SB>1_i</SB>for F1 and ϕ<SB>2_1</SB>for F2) of variable phase shifting means connected to (i)th element antennas of respective frequency bands are set to ratios of ϕ<SB>2_i</SB>=ϕ<SB>1_i</SB>×f<SB>2</SB>/f<SB>1</SB>and ϕ<SB>j_i</SB>=ϕ<SB>1_i</SB>×f<SB>j</SB>/f<SB>1</SB>, and the respective frequency bands to compensate the antenna pattern deformation. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a satellite-mounted array-fed reflector antenna having an antenna pattern deformation compensation function in geostationary orbit.

Satellite mounted antennas in geostationary orbits have their antenna patterns deformed due to factors such as satellite attitude control, reflection mirror and feeding part mounting errors, and deformation of the reflecting mirror surface, resulting in degradation of characteristics. In order to realize the antenna pattern deformation compensation of a conventional satellite-fed array-fed reflector antenna,
1. 1. Removal of the factor itself by changing the physical position of the antenna Depending on the amount of antenna pattern deformation, there is an update of the excitation amplitude / phase coefficient for beam formation. Prior art Changes the physical position, such as the mounting angle of the reflecting mirror, according to the antenna pattern deformation. Then, it electrically compensates by updating the excitation amplitude and the phase coefficient for beam formation (nonpatent literature 1).
"Yoshinori Suzuki, Akira Meguro, Masazumi Ueha," Examination of pointing error compensation method for phased array fed reflector multi-beam antenna ", 2005 IEICE General Conference, B-3-22, pp.350, Mar. 2005 ”

  In order to improve the performance of geostationary satellites, it is essential to increase the gain by increasing the size of the onboard antenna. In order to achieve this, it is common to reduce the weight by configuring the mirror surface with a mesh. The antenna pattern deformation factor in orbit includes reflection mirror deformation due to the effects of alignment error, satellite attitude variation, and sunlight, and accompanying this, antenna pattern deformation occurs and characteristics deteriorate.

  Antenna pattern deformation due to alignment error or satellite attitude variation is a deformation that shifts the entire service area while maintaining the relative positional relationship of the antenna pattern of the formed beam. Then, it is possible to cope by changing the physical position of the antenna. However, in the case of reflecting mirror surface deformation, since the entire service area is enlarged / reduced and the relative position of each beam changes, there is a problem that antenna pattern deformation compensation due to a physical position change cannot be realized.

  On the other hand, the conventional technique 2. Then, as described in Non-Patent Document 1, due to the effects of alignment errors and satellite attitude fluctuations, “a deformation component that shifts the entire service area while maintaining the relative positional relationship of the antenna pattern of the formed beam (hereinafter referred to as the pointing direction”). Error component) ”and“ deformation component that expands / contracts the entire service area (hereinafter referred to as “specular deformation component”) ”due to the effect of reflector deformation. Compensation techniques have been reported. However, when applied to a multi-beam antenna sharing a plurality of frequency bands, the common phase shift amount of the variable phase shift means for antenna pattern deformation compensation means that the antenna pattern is shifted as a result of the following analysis. It became clear. That is, since the same set value cannot be used in a plurality of frequency bands, the calculation means for determining the amount of phase shift requires the same number as the number of frequency bands.

Here, as an antenna operating in a plurality of frequency bands, a transmission / reception shared antenna is taken as an example. As shown in FIG. 1 and FIG. 2, an array-fed reflector multi-beam antenna having an antenna pattern deformation compensation function includes a reflector, an array feeder, a transmission / reception signal separating unit, an antenna pattern deformation compensating unit, and a multi-beam forming unit. Consists of. The antenna pattern deformation compensation means is composed of a variable phase shift means and its control means. FIG. 3 shows a rotating paraboloid having a transmission frequency band: f _tx as a reference frequency band and an aperture diameter of 158.3 wavelengths as a reflecting mirror, a focal length of 110.8 wavelengths, and an array feed unit having 91 element antennas spaced by one wavelength This is an example of antenna pattern analysis of a triangle-arranged transmission / reception shared array-fed reflector multi-beam antenna, and it is suitable for each beam by the multi-beam forming means so as to form a beam in the area indicated by the dotted circle in the figure. After performing the amplitude / phase shift setting, beam formation was performed. The contour lines indicated by black lines indicate the level of 43 dBi in the transmission frequency band: f _{tx, and} the alternate long and short dash lines indicate the level of 43 dBi in the reception frequency band: f _rx = 1.2 f _tx (hereinafter the same applies to the contour lines). . FIG. 4 shows an analysis result obtained by scanning the formed three beams in the azimuth direction in order to realize compensation of the directivity direction error. For the variable phase shift means in the transmission frequency band and the variable phase shift means in the reception frequency band, The same phase shift amount was given. Further, FIG. 5 shows an enlarged view of the vicinity of the forming beam in the northeastern part, and a deviation in the pointing direction can be confirmed. Generally, since the pointing direction error in the mounted antenna is required to be about 1/10 of the beam diameter, it can be confirmed that the requirement is not satisfied when the specified value of the same variable phase shift means is used in different frequency bands. . Regarding the specular deformation component, as shown in FIG. 6, the directing direction of the main beam is hardly changed, and even if the default value of the same variable phase shift means is used, it is about 1/10 of the beam diameter. It can be confirmed that the required orientation error is satisfied.

  As described above, the specular deformation component can use the same setting value for the variable phase shift means in a plurality of frequency bands, but the pointing direction error component has the same setting for the variable phase shift means in a plurality of frequency bands. The value cannot be used. Therefore, the required amount of phase shift differs depending on the frequency. That is, there is a problem that a calculation means for determining the amount of phase shift is required for each frequency band, and the circuit scale increases accordingly.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an array-fed reflector antenna that can electrically compensate for antenna pattern deformation due to satellite attitude variation, reflector and feeder attachment errors, and reflector surface deformation with a smaller circuit scale. Is to provide.

  An array-fed reflector antenna according to the present invention includes an array feed unit including a reflector operating in two or more frequency bands, and a plurality of element antennas arranged in front of the focal plane of the reflector, and each element of the array feed unit. A signal separation unit for the frequency band connected to the antenna, and a beam corresponding to each frequency band for exciting each antenna element of the array feeding unit with a predetermined amplitude and phase connected to a terminal corresponding to each frequency band of the signal separation unit In order to compensate for antenna pattern deformation, variable phase shifting means corresponding to the frequency band is loaded between each terminal of the signal separating means and the beam forming means, and the variable phase shifting means in each frequency band The ratio of the amount of phase shift is set to be the ratio of the frequencies in each frequency band.

  As an embodiment of the present invention, an array-fed reflector antenna includes a phase shift amount calculating means for compensating for deformation of an antenna pattern in a predetermined reference frequency band, and a phase shift amount in each frequency band of a variable phase shift means. There is further provided a set phase shift amount changing means for giving a phase shift amount so that the ratio is a frequency ratio of each frequency band.

  This design phase shift amount changing means can give the variable phase shift for reception so that the ratio between the transmission frequency band and the reception frequency band becomes the ratio of the variable phase shift amount for transmission.

  As another embodiment of the present invention, the variable phase shift means is such that the phase shift amount is directly proportional to the frequency band and the control value for determining the phase shift amount in the variable phase shift means corresponding to the frequency band is the same value. It is.

  This phase shifting means can also be a line switching type phase shifting means.

  The array-fed reflector antenna operating in a plurality of frequency bands according to the present invention requires only one set of large reflectors, and also includes an attitude control of the satellite in orbit, attachment errors of the reflector and feeder, and deformation of the reflector surface. Since the pattern deformation can be electronically compensated for all the beams at the same time and the control means can be simplified, the effect of reducing the weight and power consumption and improving the reliability is great.

  The antenna pattern deformation error in the array-fed reflector antenna is classified into a directivity direction error component and a mirror surface deformation component, and the amount of phase shift for each component compensation is as shown in FIG. Compensation of the pointing direction error component gives a phase shift amount that is virtually rotated, and compensation of the specular deformation component gives a phase shift amount so as to virtually have a curvature. In other words, in the shared antenna for transmitting and receiving reflector antennas, the physical shape is the same, and the antenna pattern deformation error is almost the same even if the frequency is different, so the virtual array feeding aperture for compensation is the same. It is. However, when this is realized electrically, the required amount of phase shift differs depending on the frequency. In order to solve this, the set phase shift amount corresponding to each frequency band may be the ratio of each frequency band.

More specifically, in an array-fed reflector antenna that operates in two or more frequency bands (F1, F2,...), It is connected to the i-th element antenna in each frequency band in order to compensate for antenna pattern deformation. phase shift amount of the variable phase unit (for _F1: φ 1_i, F2 _for: φ 2_i, ...) to the relationship of each party _{φ 2_i = φ 1_i · f 2} / f 1, ..., φ j_i = φ 1_i・ F _j / f ₁ ,…
And the ratio of each frequency band.

  Furthermore, when applying a variable phase shift control means represented by a line switching type in which the phase shift amount is proportional to the frequency, if the control value is the same, the set phase shift amount is the ratio of each frequency band. It becomes.

  The present invention provides an array-fed reflector antenna in which the ratio of the phase shift amount in each frequency band of the variable phase shift means is the ratio of the frequency in each frequency band as described above.

  In the following, the present invention will be described based on an embodiment using an array-fed reflector multi-beam antenna. This embodiment is an explanation of an array-fed reflector multi-beam antenna having a plurality of beams. However, the present invention can also be applied to an array-fed reflector antenna having one beam.

  FIG. 1 shows the configuration of an array-fed reflector multi-beam antenna that is an object of the present invention, and is composed of a reflector a and a feeder b arranged in front of the focal plane a2 of the reflector a.

  FIG. 8 shows the configuration of an array-fed reflector multi-beam antenna for both transmission and reception (transmission frequency: Ftx, reception frequency: Frx) according to an embodiment of the present invention. The antenna includes a reflecting mirror a, an array feeder b composed of a plurality of element antennas, signal separation means c1 to cn for each frequency band connected to the element antennas b1 to bn of the array feeder b, the array Each antenna element is composed of a transmitting multi-beam forming means etx and a receiving multi-beam forming means erx for exciting the element antennas b1 to bn of the power supply unit b with a predetermined amplitude and phase shift, and compensates for antenna pattern deformation. Variable phase shifting means d1_tx1 to d1_txn, d1_rx1 to d1_rxn are arranged between b1 to bn and the multi-beam forming means, and the antenna pattern deformation detecting means d2 and the antenna pattern deformation in a predetermined reference frequency band (here Ftx) A phase shift amount calculation means d3 for compensation is provided.

  The antenna pattern deformation detecting means d2 determines the directivity direction error of the array-fed reflector multibeam antenna from the reception and transmission levels at three or more different geographical positions, and the directivity error component and mirror surface of the array-fed reflector multibeam antenna. The deformation component is calculated. A phase shift amount for compensating each detected error is obtained from the phase shift amount calculation means d3. As a method for determining the amount of phase shift for compensating the pointing direction error component, the amount of phase shift is determined such that the antenna elements b1 to bn are electrically located on the virtual aperture plane indicated by the dotted line in FIG. The method for determining the amount of phase shift that compensates for the specular deformation component finds the amount of phase shift such that the antenna elements b1 to bn are electrically located on the virtual aperture plane indicated by the dotted line in FIG. 7B.

  In the present embodiment, the phase shift amount calculated here is for the transmission frequency band. In order to apply this to the reception frequency band, the ratio of the amount of phase shift in each frequency band is the ratio of the frequency in each frequency band. The variable phase shift amounts φrx_1 to φrx_n for reception are compared with the reference frequency band with respect to the variable phase shift amounts φtx_1 to φtx_n for transmission connected to the respective element antennas b1 to bn for the antenna pattern deformation compensation for transmission. Is given by the design phase shift amount changing means d4.

That is, the design phase shift amount changing means d4 is a phase shift amount of the variable phase shift means connected to the i-th element antenna in the reception frequency band (Frx).
φrx_i = φtx_i × Frx / Ftx
give. Here, φtx_i is a phase shift amount of the variable phase shift means connected to the i-th element antenna in the reference frequency band (that is, transmission frequency band) given from the phase shift amount calculation means d3.

  FIGS. 9 to 11 show the analysis results when assuming the compensation of the pointing method error component and the specular deformation compensation component by this method. As a result, the direction of the formed beam in the transmission frequency band and the reception frequency band is not shifted as compared with the case where the same phase shift amount is simply given (FIGS. 4 to 6) aiming at circuit scale reduction. I can confirm.

  FIG. 12 shows the configuration of an array-fed reflector multi-beam antenna for both transmission and reception (transmission frequency: Ftx, reception frequency: Frx) according to another embodiment of the present invention. The antenna includes a reflecting mirror a, an array feeder b composed of a plurality of element antennas, signal separation means c1 to cn for each frequency band connected to the element antennas b1 to bn of the array feeder b, the array Each antenna element is composed of a transmitting multi-beam forming means etx and a receiving multi-beam forming means erx for exciting the element antennas b1 to bn of the power supply unit b with a predetermined amplitude and phase shift, and compensates for antenna pattern deformation. Variable phase shifting means d1_tx1 to d1_txn, d1_rx1 to d1_rxn are arranged between b1 to bn and the multi-beam forming means, and the antenna pattern deformation detecting means d2 and the antenna pattern deformation in a predetermined reference frequency band (here Ftx) A phase shift amount calculation means d3 for compensation is provided.

  The antenna pattern deformation detecting means d2 calculates the directivity direction error of the array-fed reflector multi-beam antenna, and the phase shift amount for compensating for the detected error is obtained from the phase shift amount calculating means d3. In the present embodiment, the phase shift amount calculated here is for the transmission frequency band.

  Here, the receiving variable phase shifting means d1_rx1 to d1_rxn for compensating for the antenna pattern deformation is such that the phase shift amounts φrx_1 to φrx_n are directly proportional to the operating frequency, and the phase shifting in the receiving variable phase shifting means d1_rx1 to d1_rxn is performed. The control value for determining the amount (here, the phase shift amount of the variable phase shift means for transmission) is the same value.

As a variable phase shift means whose phase shift amount is directly proportional to the frequency, there is a line switching type phase shift means. In this case, the variable phase shift amounts φrx_1 to φrx_n for reception are
φrx_i = 2π × (L2-L1) / λ _g
Given in. Here, lambda _g is the wavelength in the transmission line, L1, L2 are each a distance in the line switching type phase shifting means.

  The variable phase shifting means d1_tx1 to d1_txn and d1_rx1 to d1_rxn corresponding to the frequency bands loaded between the terminals of the signal separating means for compensating for the antenna pattern deformation of this embodiment and the multi-beam forming means are discretely distributed. It does not matter whether the phase shift amount changes or the phase shift amount changes continuously.

  All the embodiments described above are illustrative of the present invention and are not intended to be limiting, and the present invention can be implemented in other various modifications and changes. Therefore, the scope of the present invention is defined only by the claims and their equivalents.

The structure of an array-fed reflector multibeam antenna is shown. The block diagram of an array electric power feeding part, an antenna pattern deformation compensation apparatus, and a beam forming apparatus is shown. An analysis example of an array-fed reflector multibeam antenna is shown. An analysis example 1 of the array-fed reflector multi-beam antenna when the same phase shift amount is given is shown. An analysis example 2 of the array-fed reflector multi-beam antenna when the same phase shift amount is given is shown. An analysis example 3 of the array-fed reflector multi-beam antenna when the same phase shift amount is given is shown. The concept of the amount of phase shift which compensates for antenna pattern deformation is shown. The structure (excluding a reflective mirror) of the transmission / reception shared array feeding reflective mirror multi-beam antenna by this invention is shown. An analysis example 1 of an array-fed reflector multi-beam antenna in the case of giving different phase shift amounts according to the present invention will be shown. An analysis example 2 of the array-fed reflector multi-beam antenna when the phase shift amounts for transmission and reception according to the present invention are given will be shown. An analysis example 3 of the array-fed reflector multi-beam antenna when the phase shift amounts for transmission and reception according to the present invention are given will be shown. 1 shows a configuration (excluding a reflector) and a variable phase-shifting means of an array-fed shared-feed reflector multi-beam antenna according to the present invention.

Explanation of symbols

a Reflector a1 Focal point of reflector a2 Reflector focal plane b Array feeder b1 to bn Element antenna c Signal separation means d Antenna pattern deformation compensation means dtx Transmit drx Receive d1_tx1 to d1_txn, d1_rx1 to d1_rxn Variable phase shift means φtx_1 to φtx_n, φrx_1 to φrx_n variable phase shift means d1_tx1 to d1_txn, phase shift amount in d1_rx1 to d1_rxn d2 antenna pattern deformation detection means d3 phase shift amount calculation means d4 set phase shift amount change means e multi-beam forming means etx for transmission er E1 distributor for reception e2 fixed phase shifter e3 fixed subtractor e4 power combiner F operating frequency

Claims (5)

A reflector operating in two or more frequency bands;
An array feeding unit composed of a plurality of element antennas arranged in front of the focal plane of the reflecting mirror;
Signal separating means for the frequency band connected to each element antenna of the array feeding section;
Beam forming means corresponding to each frequency band for exciting each antenna element of the array feeding section with a predetermined amplitude and phase connected to a terminal corresponding to each frequency band of the signal separation means;
In an array-fed reflector antenna composed of
In order to compensate for antenna pattern deformation, variable phase shift means corresponding to the frequency band is loaded between each terminal of the signal separation means and the beam forming means,
The array-fed reflector antenna characterized in that the ratio of the amount of phase shift in each frequency band of the variable phase shift means is the ratio of the frequencies in each frequency band. A phase shift amount calculating means for compensating for deformation of an antenna pattern in a predetermined reference frequency band;
2. A set phase shift amount changing means for providing a phase shift amount so that a ratio of phase shift amounts in each frequency band of the variable phase shift means becomes a ratio of frequencies in each frequency band. An array-fed reflector antenna as described in 1.   The variable phase shift means is characterized in that the amount of phase shift is directly proportional to the frequency band, and the control value for determining the phase shift amount in the variable phase shift means corresponding to the frequency band is the same value. The array-fed reflector antenna according to claim 1.   3. The design phase shift amount changing means provides a variable phase shift amount for reception so that a ratio of a transmission frequency band and a reception frequency band is set to a variable phase shift amount for transmission. The array-fed reflector antenna described.   4. The array-fed reflector antenna according to claim 3, wherein the variable phase shifting means is a line switching type phase shifting means.

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