JP2009232213A - Multiband array antenna - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inexpensive multiband array antenna which suppresses pattern deterioration of an array antenna to be used in multiband. <P>SOLUTION: A plurality of elements units, each being constituted of a low-frequency element and a narrow-beam high-frequency element, are arrayed on a predetermined array surface at intervals corresponding to low frequency, so as to suppress high-frequency grating lobe. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a multiband array antenna, and more particularly to a multiband array antenna using a low-frequency element and a high-frequency element.

  In general, an array antenna is configured by arranging antenna elements side by side on a planar, cylindrical, or spherical arrangement surface. In the phased array antenna, a beam scanning is performed by mounting a module having a phase shifter for each antenna element side by side on the arrangement surface and controlling a signal of the antenna element by the phase shifter.

  A multi-band phased array antenna has a high frequency (high frequency) element (high frequency element) and a low frequency (low frequency) element (low frequency element) when arranged with element spacing that does not produce grating lobes. The frequency ratio is about the square of the number, and the number of high-frequency modules including phase shifters and the like increases (see Patent Document 1). In addition, the arrangement of the low-frequency elements and the high-frequency elements has physical restrictions, and electrical interference occurs, resulting in pattern disturbance (see Patent Document 2).

  FIG. 8 is a diagram showing a configuration example of a multiband phased array antenna according to the related art of the present invention.

  FIG. 8A shows an element arrangement of 2 × 2 elements in the low band and 4 × 4 elements in the high band, and the low band elements and the high band elements are multilayered and arranged on the same plane.

  FIG. 8B shows a power supply circuit diagram in the case of a phased array antenna, and modules each having a phase shifter are connected to the low-frequency element and the high-frequency element. A low-frequency element S1 and a high-frequency element S2 are connected to the low-frequency module 11 and the high-frequency module 12, respectively, thereby forming a phased array antenna.

  FIG. 8C shows an example of a multiband element structure. The low-frequency element S1 is disposed on the upper layer of the multilayer substrate 15, and the high-frequency element S2 is disposed on the lower layer (lower side) of the low-frequency element S1. Further, the upper layer low-frequency element S1 is formed in a net shape so as to improve transmission of radio waves at a high frequency (Non-Patent Document 1).

The structure of the multiband element is also disclosed in Patent Documents 1 and 3, but is not directly related to the present invention, and therefore detailed description thereof is omitted.
JP-A-4-35208 JP 2002-164736 A JP-A-8-186437 IEE Proceedings Vol.135, Part H, No.5, October 1988, pages 304 to 312 “Superimposed Dichroic Microstrip antenna array” by JRjames et al.

  Multi-band array antennas are arranged at element intervals that do not produce grating lobes (side lobes), so the number of high-frequency elements is approximately the square of the frequency ratio compared to the number of low-frequency elements. Etc. also increases (see Patent Document 1). Further, the arrangement of the low-frequency elements and the high-frequency elements has physical restrictions, and electrical interference occurs, resulting in pattern disturbance.

  As described above, a multiband array antenna having an element interval that does not generate grating lobes is expensive due to an increase in the number of high-frequency elements, high-frequency modules, and the like.

  Therefore, in order to reduce the number of elements of the multiband array antenna, a grating lobe occurs when the element spacing of the high-frequency elements is made the same as the element spacing of the low-frequency elements.

  In the multiband array antenna, the low-frequency elements and the high-frequency elements are interlaced, and the element pattern of the high-frequency elements is particularly disturbed, leading to deterioration of side lobes in the array pattern.

(the purpose)
An object of the present invention is to solve the above-mentioned problems and to provide an inexpensive multiband array antenna that suppresses pattern deterioration of an array antenna used in multiband.

  The multi-band array antenna of the present invention can suppress a high-frequency grating lobe by arranging a plurality of element units composed of low-frequency elements and narrow-beam high-frequency elements on a predetermined arrangement surface at intervals corresponding to low frequencies. It is characterized by that.

  According to the present invention, by arranging the element units at low-frequency element intervals, the number of antenna elements, the number of high-frequency modules, etc. can be greatly reduced, and the increase in the hardware scale of the apparatus is avoided. Price reduction.

  Even if the number of elements is reduced by arranging the high frequency elements at the same element spacing as the low frequency elements, an array pattern in which the grating lobe is suppressed can be obtained. That is, it is possible to suppress the grating crobe that occurs when the element spacing is increased by narrowing the high-frequency element pattern.

  Furthermore, since the number of high-frequency elements is reduced and the element arrangement can be simplified, physical restrictions and electrical interference are reduced.

(First embodiment)
(Description of configuration)
Next, a first embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a diagram showing a first embodiment of a multiband array antenna according to the present invention, where (a) is a cylindrical type, (b) is a planar type, and (c) is an element array. This embodiment shows an application example to a radar antenna device.

  FIG. 1A shows a cylindrical array antenna in which elements are arranged in a cylindrical curved surface. The cylindrical array antenna 1 is installed on the base 3, and an excitation element is selected by a switch and switched to scan a horizontal plane beam.

  FIG. 1B shows a planar array antenna in which the arrangement surface is a planar plane. The array antenna 2 is mechanically rotated by the pedestal 4 between the base unit 3 and the array antenna 2 to scan a horizontal plane beam.

  FIG. 1C shows a configuration example of the element arrangement of the antenna openings in FIG. In the present embodiment, a plurality of element units 5 configured by disposing a high-frequency element 52 as a central high-frequency conductor and a low-frequency element 51 as a low-frequency conductor are arranged in a line in the vertical direction.

  Further, the low-frequency element 51 of the element unit 5 is a wide beam, the high-frequency element 52 is a narrow beam, and the element units 5 of each line are arranged at intervals such that a low-frequency grating lobe (side lobe) can be suppressed. Between the lines, the element units 5 are vertically arranged in a triangular arrangement with a ½ array interval shifted. The interval between the columns or the element interval of each column can be a ½ array interval.

  Next, a specific configuration example of the element antenna by the element unit 5 in which the low-frequency element 51 of the present embodiment is a wide beam and the high-frequency element 52 is a narrow beam will be described.

FIG. 2 is a diagram showing a configuration example of an element antenna having a wide beam at a low frequency and a narrow beam at a high frequency.
In the method shown in FIG. 2 (a), as one element unit 5, a low-frequency element 51 is arranged in the upper layer of the multilayer substrate, and a plurality of high-frequency elements 52 are arranged in the lower layer below it. By synthesizing the signals of the element 52, a small array is formed, and the narrow beam of the high-frequency element 52 is realized. For example, the low-frequency element and the high-frequency element of the element unit are both patch antennas, and the high-frequency element 52 is a small array antenna (patch small array antenna) with 3 × 3 patches to realize a narrow beam.

  In the method shown in FIG. 2B, a low-band / high-band multiband element is formed by a conductor low-frequency element 51 as the element unit 5 and a conductor high-frequency element 53 formed at the center of the low-frequency element 51. By constructing and adding a parasitic element 53 acting as a director to the high-frequency element, a narrow beam of the high-frequency element 52 is realized. For example, the low-frequency element and the high-frequency element of the element unit are both patch antennas, and the high-frequency element 52 is a patch with a parasitic element to realize a narrow beam.

  In the system shown in FIG. 2 (c), the antenna uses a conductor corner reflector 55, and a dipole antenna post is provided from the valley portion of the corner reflector 55, and a dipole in which low-band / high-band multiband elements are combined. The element unit 5 in which the antenna is arranged is configured as a low-frequency / high-frequency shared antenna element that shares the opening surface, thereby realizing a narrow beam in the high frequency range. For example, the high-frequency element of the element unit is a short element at the center and the low-frequency element is a long element including both ends, and a narrow beam is realized as a low-frequency / high-frequency dual-frequency dipole with a corner reflector.

  In the method shown in FIG. 2 (d), the antenna is a multiband horn type antenna, the antenna element of the low band / high band multiband horn 56 is arranged, and the element unit 5 has a low band / high band sharing the opening surface. It is configured as a shared antenna element and realizes narrowing of the high band with the same aperture.

  Next, a configuration example of the power feeding circuit of the multiband array antenna of this embodiment will be described.

  FIG. 3 is a diagram illustrating a configuration example of a power feeding circuit of an element unit including a broadband module.

  FIG. 3A shows an array synthesis two-point power feeding circuit corresponding to the element unit shown in FIG. This is a power supply circuit having a configuration in which the combining / distributing circuit 7 connected to the high-frequency elements 52 (# 1 to #n) and the low-frequency element 51 are connected to the broadband module 6 via the switch 8 that switches between the high frequency and the low frequency.

  FIG. 3B shows a configuration example of a two-point power feeding circuit corresponding to the element unit shown in FIG. This is a power supply circuit having a configuration in which the low-frequency element 51 and the high-frequency element 52 are connected to the broadband module 6 via a switch 8 that switches between a high frequency and a low frequency.

  FIG. 3C shows a single-point power feeding circuit corresponding to the element unit shown in FIGS. 2C and 2D. This is a power feeding circuit having a configuration in which antenna elements 54 and 55 for multi-frequency use that share an opening surface in a low range and a high range using a corner reflector or a horn are connected to the broadband module 6.

(Description of operation)
Next, operations related to the antenna structure and scanning of each multiband array antenna of the present embodiment will be described.

  In the case of the cylindrical phased array antenna shown in FIG. 1A, the horizontal direction is electronically scanned by selecting an excitation element with a switch. In addition, the module phase shifter enables wide-angle scanning in the low range and micro-angle scanning in the high range.

  That is, since the element pattern is narrowed at high frequencies, the excitation element array is limited. The phased array antenna is suitable for a radar antenna apparatus for searching and tracking a target.

  In the case of the planar type phased array antenna shown in FIG. 1B, the horizontal direction is mechanically scanned by the pedestal 4. Further, the module phase shifter enables wide angle scanning in the low range and fine angle scan in the high range, and is suitable for a radar antenna apparatus for searching and tracking a target.

  FIG. 1C is a diagram showing the element arrangement of FIGS. 1A and 1B, and the element unit intervals are arranged so as not to generate grating lobes with intervals corresponding to low frequencies.

  Next, the antenna structure of each multiband array antenna according to this embodiment and the operation for realizing a wide beam in the low band and a narrow beam in the high band will be described.

  FIG. 2 (a) is a configuration example using the structure shown in FIG. 8 (c), but the number of high-frequency elements (number of patches) is 3 × 3 with respect to one element (patch) of low-frequency elements. As shown in FIG. 3A, each element of the high-frequency element is connected to the combiner / distributor 7 as a power feeding circuit, and is configured as a small array to narrow the beam of the high-frequency element pattern. The low-frequency element and the high-frequency element are connected to the broadband module via the switch 8 to reduce the number of modules.

  FIG. 2B is a configuration example of a multi-band element having a patch two-layer structure. A parasitic element that functions as a waveguide element in the high band is arranged in front of the high band element 52 to narrow the beam. Yes. Further, as shown in FIG. 3B, the power feeding circuit feeds power to two points, a high band and a low band.

  FIG. 2C shows a structure in which a multiband element 54 having a dipole structure and a corner reflector 55 are combined. The high-frequency pattern is narrowed by sharing the opening surface of the corner reflector 55. Further, as shown in FIG. 3C, the power feeding circuit feeds power to one point sharing the high and low frequencies.

  FIG. 2D shows a configuration example using a horn structure multiband element. The horn 56 as the element unit 5 is a low-frequency / high-frequency dual-frequency horn composed of a plurality of horns sharing the opening surface, thereby narrowing the high-frequency pattern. Further, as shown in FIG. 3C, the power feeding circuit feeds power to one point sharing the high and low frequencies.

  In addition, as an example of the power feeding circuit, a phase shifter corresponding to FIGS. 2 (a), (b), (c) and (d) as shown in FIGS. 3 (a), (b) and (c). The provided broadband module is used.

  Next, the array pattern of each multiband array antenna of this embodiment will be described.

  FIG. 4 is a diagram showing a pattern of each element of the low-frequency element and high-frequency element of the element unit, and FIG. 5 is a case where 40 element units in the horizontal direction and 40 element units in the elevation angle direction are arranged in a triangle at 1.5 wavelength intervals. It is a figure which shows the array pattern of. When the frequency ratio between the low band and the high band is three times, if the low band elements are arranged at intervals of 0.5 wavelength, the high band has 1.5 wavelength intervals, and FIG. 5 shows a high band pattern in this case.

  4A shows the element pattern characteristics of the wide beam 511 in the low band and the narrow beam 521 in the high band, and FIG. 4B shows the element pattern characteristics of the wide beams 511 and 522 in both the low band and the high band. Show.

  FIG. 5A shows the characteristics of the array pattern as a result of simulation with the element pattern shown in FIG. 4A, and FIG. 5B shows the array pattern as a result of simulation with the element pattern shown in FIG. 4B. It is a characteristic.

  As can be seen from a comparison between FIG. 5 (a) and FIG. 5 (b), when the array antenna has a wide beam element pattern for both low and high frequencies as shown in FIG. Lobes (side lobes) are generated.

  On the other hand, when the array antenna is an element pattern having a wide beam in the low band and a narrow beam in the high band as shown in FIG. 4A, the grating lobe (side lobe) is reduced in the array pattern.

  As described above, in the present embodiment, the antenna element having a wide beam in the low band and a narrow beam in the high band is used as one element unit, and the element units are arranged at intervals capable of suppressing the low-frequency grating lobes (side lobes). Configure the array. If the high-frequency element pattern is a wide beam like the low-frequency element pattern, grating lobes (side lobes) are generated in the array pattern, but if multi-band element units are arranged at low-frequency element intervals, Although the element spacing in the high band increases with respect to the wavelength, the grating lobe (side lobe) is reduced because the element pattern is narrowed.

  By arranging multiband element units at low-frequency element intervals, the number of high-frequency modules and the like can be reduced to the same number as for low-frequency elements. Further, if the low band / high band are shared using a broadband module, the number can be halved. As a result, the price can be reduced without increasing the hardware scale of the multiband array antenna.

(Second Embodiment)
FIG. 6 is an external view showing a multiband array antenna according to the second embodiment of the present invention.
An array antenna 14 in which the multiband element units of the first embodiment shown in FIG. 2 are arranged in the same manner as in FIG. 1C, and 2 in the horizontal direction (AZ) and vertical direction (EL) on the base 3 And a pedestal 13 having a shaft rotation mechanism.

  A planar multiband array antenna 14 is an antenna device in which beam operations are mechanically performed for both AZ and EL by a biaxial pedestal 13.

  FIG. 7 is a configuration example of a feeding circuit of the antenna element according to the second embodiment. FIG. 7A is a configuration example of a two-point power feeding system shown in FIGS. 3A and 3B when the element unit 5 shown in FIGS. 2A and 2B is used. The low band combiner / distributor 9 for the low band element 51 and the high band combiner / distributor 10 for the high band element 52 are configured.

  FIG. 7B is a configuration example of the one-point power feeding circuit shown in FIGS. 3C and 3D when the element unit 5 shown in FIGS. 2C and 2D is used. The low-frequency / high-frequency shared element 54 or the horn 55 is configured by a low-frequency synthesis distributor 9 and a high-frequency synthesis distributor 10 connected via a switch 7 that switches between a low frequency and a high frequency.

  7 (a) and 7 (b), the low-frequency synthesizer / distributor 9 and the high-frequency synthesizer / distributor 10 combine the signals (reception) of the respective element units or distribute the signals (transmission) to the respective element units. Form the beam.

  Beam scanning is performed by mechanical rotation in both the horizontal direction (AZ) and vertical direction (EL) as shown in FIG. 6 to suppress grating lobes, simplify the element arrangement, and prevent pattern disturbance by reducing electrical interference. An effect is obtained.

  Also in the present embodiment, an antenna element having a wide beam in the low band and a narrow beam in the high band as one element unit, and an array in which the element units are arranged at intervals capable of suppressing the low-frequency grating lobes (side lobes). Constitute. If the high-frequency element pattern is a wide beam like the low-frequency element pattern, grating lobes (side lobes) are generated in the array pattern, but if multi-band element units are arranged at low-frequency element intervals, Although the element spacing in the high band increases with respect to the wavelength, the grating lobe (side lobe) is reduced because the element pattern is narrowed.

  By arranging multi-band element units with element spacing corresponding to the low frequency, the number of elements for high frequency can be reduced to the same number as for low frequency, leading to an increase in the hardware scale of the multi-band array antenna. Therefore, the price can be reduced.

(Other embodiments)
In the above embodiment, the power supply circuit has shown an example of using a broadband module as shown in FIGS. 3A, 3B, and 3C. However, it is configured using two types of modules for low frequency and high frequency. It is also possible to do.

  The frequency band of the antenna is not limited to two frequency bands, a low band and a high band, but can be applied to an array of three or more bands or a wide band.

  Further, in the embodiment shown in FIG. 1, the configuration example of the triangular array shown in FIG. 1C is shown as the element array, but the same effect can be obtained even if the element array is a square array. In addition, the arrangement of the element units shown in FIG. 2 shows a configuration example of a square array, but it is obvious that a configuration of a triangular array can be similarly formed.

  In the embodiment shown in FIG. 6, a configuration example of a planar antenna is shown as a multiband array antenna without a module. However, the present invention can also be applied to a cylindrical antenna shown in FIG. .

It is a figure which shows 1st Embodiment of the multiband array antenna of this invention, (a) is a cylindrical type, (b) is a planar type, (c) is an element arrangement | sequence. It is a figure which shows the structural example of the element antenna which becomes a wide beam in the low region of 1st Embodiment, and becomes a narrow beam in a high region. It is a figure which shows the structural example of the electric power feeding circuit of the element unit which comprised the broadband module of 1st Embodiment. It is a figure which shows the pattern of the element single-piece | unit of each of the low-frequency element and high-frequency element of an element unit. It is a figure which shows an array pattern at the time of arrange | positioning a horizontal 40 element unit and an elevation angle direction 40 element unit at a 1.5 wavelength space | interval of a low frequency element. It is an external view which shows 2nd Embodiment of the multiband array antenna of this invention. It is a structural example of the electric power feeding circuit of the antenna element of 2nd Embodiment. It is a figure which shows the related technique of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Cylindrical array antennas 2 and 14 Planar array antenna 3 Base part 4 Pedestal 5 Element unit 51 Low-frequency element 52 High-frequency element 53 Parasitic element 54 Low-frequency / high-frequency shared element 55 Horn 56 Corner reflector 511 Low-frequency element pattern 521 522 High-frequency element pattern 6 Broadband module 7 Synthesizer / distributor 8 Switch 9 Low-frequency synthesizer / distributor 10 High-frequency synthesizer / distributor 11 Low-frequency module 12 High-frequency module 13 Biaxial pedestal 15 Multi-layer substrate

Claims (13)

A multiband array characterized in that a plurality of element units composed of low-frequency elements and narrow-beam high-frequency elements are arranged on a predetermined arrangement surface at intervals corresponding to the low-frequency range so that high-frequency grating lobes can be suppressed. antenna. 2. The multiband array antenna according to claim 1, wherein the array surface is a cylindrical curved surface. The multiband array antenna according to claim 1, wherein the array surface is a planar surface. 4. The multiband array antenna according to claim 1, further comprising a module having a phase shifter for each element unit. 5. The multiband array antenna according to claim 4, wherein the low-frequency element and the high-frequency element are connected to the module via a switcher that switches between a low frequency and a high frequency. The multiband array antenna according to any one of claims 1 to 5, wherein each of the low-frequency element and the high-frequency element is configured as a patch antenna. 6. The multiband array antenna according to claim 1, wherein the low-frequency element and the high-frequency element are configured as a small array of patch antennas and patch antennas, respectively. The multi-band array antenna according to claim 7, wherein each patch antenna of the small array is connected to a combiner / distributor. The multiband according to any one of claims 1 to 4, wherein the low-frequency element and the high-frequency element are configured by a multi-frequency antenna element that shares an aperture plane in a low frequency region and a high frequency region. Array antenna. 4. The multi-band array according to claim 1, wherein the low-frequency element and the high-frequency element are respectively connected to a low-frequency synthesis distributor and a high-frequency synthesis distributor. antenna. The low-frequency element and the high-frequency element are configured by a multi-frequency antenna element that shares an aperture surface between the low frequency and the high frequency, and each of the low frequency synthesis distributor and the low frequency element via a switch that switches between the low frequency and the high frequency. 4. The multiband array antenna according to claim 1, wherein the multiband array antenna is connected to a high frequency band combiner / distributor. The multiband array antenna according to claim 9 or 11, wherein the antenna element is configured as a horn antenna. The multiband array antenna according to claim 9 or 11, wherein the antenna element is configured as a dipole antenna having a reflector.

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