JP2019047238A - Array antenna - Google Patents

Abstract

To provide an array antenna capable of restraining deterioration of side lobe even when used in broadband.SOLUTION: In an array antenna where a first subarray including multiple radiation elements and a second subarray including multiple radiation elements are placed on a board, and including a feedline for feeding the radiation elements, a magic T is provided in the way of the feedline from an excitation source to the first and second subarrays, a signal from the excitation source is inputted to the E port of the magic T, the inputted signal is outputted from two ports other than the H port of the magic T, the multiple radiation elements included in the first subarray are fed from the first direction, and the multiple radiation elements included in the second subarray are fed from the second direction reverse to the first direction.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an array antenna, and more particularly to an array antenna provided with a feeding circuit for feeding radiation elements constituting the array antenna.

  The array antenna has a plurality of radiating elements arranged in a straight line, a plane, a curved face, etc., and excites all or part of them, and controls the excitation current (voltage) and the phase to obtain desired radiation directivity (radiation pattern) Is an antenna to obtain

  When radio waves are emitted from the array antenna, a feed circuit is used to excite individual radiation elements constituting the array antenna. The radiation elements are arranged on a printed circuit board or the like, and the individual radiation elements are connected to the feed circuit by feed lines. If the substrate is rectangular, a connection between the feed line and the feed circuit is usually provided on one side of the substrate, from which the radiation element is fed.

  The array antenna apparatus of patent document 1 is provided with the 1st board | substrate provided with a 1st feeding point, and the 2nd board | substrate laminated | stacked on the lower part and provided with a 2nd feeding point.

  A first radiation element array in which a plurality of first radiation elements are arranged in an array is formed on the first substrate. A second radiation element array in which a plurality of second radiation elements are arranged in an array is formed on the second substrate. A first feed line is formed on the first substrate for feeding the first radiation element array. The first feed line has an equal-length pattern of each of the first feed point and the plurality of first radiation elements such that the plurality of first radiation elements form linear polarization in the first polarization direction. Connect by wiring.

  Further, a second feed line for feeding power to the second radiation element array is formed on the second substrate. The second feed line includes a second feed point and a plurality of second feed points such that the plurality of second radiation elements form linear polarization in a second polarization direction orthogonal to the first polarization direction. Each of the radiating elements of the above is connected by pattern wiring of equal length. A wireless signal is output from the port on the transmitter side to the 180 degree hybrid circuit, and the first and second feeding points are fed with a phase difference of 180 degrees.

By doing so, it is possible to form linear polarization at a predetermined angle while suppressing the side lobes without making the feed line meander. (Paragraphs (0006), (0028), FIG. 2)
Moreover, in the planar antenna of patent document 2, magic T is comprised to a synthetic | combination part and it comprises each waveguide circuit in a block, and is laminated | stacked by the planar antenna of the structure electrically fed in parallel by a waveguide. In the embodiment of FIGS. 1 and 2, the antenna block B is configured by forming the four antenna elements 1 on the antenna circuit board 2 by forming the apertures in the metal plate. A feed waveguide opening 3 is formed on the bottom surface of the antenna block B, and the feed waveguide opening 3 is coupled to the in-phase synthetic waveguide through the L-shaped corner 4 formed in the in-phase synthesis feed block B0. It is output to the pipe 5. The outputs of the horizontally adjacent four-element array are in-phase combined at the first T branch T1 through the in-phase combining waveguide 5, and further combined at the second T branch T2 with the combined output of the vertically adjacent antenna elements, As a result, a total of 16 elements of in-phase combined power, that is, a monopulse sum pattern is obtained as the in-phase combined output Σ (paragraph (0007), FIG. 1, FIG. 2).

International Publication No. 2015/129089 Japanese Patent Laid-Open No. 6-252683

  However, as is apparent from FIG. 2 of Patent Document 1, power is supplied from the same direction to a plurality of radiation elements 101, 201 or 102, 202 disposed on one substrate 1 or substrate 2. That is, in the radiation elements 101 and 201 on the substrate 1, all the connection points at which the feed lines are connected to the individual radiation elements are on the back side of the radiation elements, and power is fed in the direction from the back to the front in FIG. Similarly, the feed directions for the radiation elements 102 and 202 on the substrate 2 are all from the front to the back of the figure. The same applies to the other FIGS.

  The radiation characteristics of the individual radiation elements become asymmetric due, for example, to the effect that the feed line is connected to the radiation elements. Since the radiation pattern of the array antenna is obtained by multiplying the radiation pattern of the radiation element by the array factor (the directivity determined by the arrangement of the radiation element), the radiation pattern of the array antenna is also asymmetric when the radiation pattern of the radiation element is asymmetric. Become. In other words, the side lobes become asymmetric. Patent Document 1 does not show a solution for this point.

  When the feed line must be configured on the same side as the radiation element with respect to the ground plane, it is effective to suppress side lobes by making the feeding direction of the radiation element symmetrical with respect to the central axis. However, there is a disadvantage that half of the array is in reverse phase. It is possible to electrically adjust the phase using a delay circuit that delays this by half a wavelength, and when the used band is narrow, the phase can be adjusted by that method. However, when the band is wide, the phase is not aligned at the edge of the band and the side lobes are degraded.

  Further, in Patent Document 2, since the Σ signal is input from the excitation source to the H port (narrow wall surface) of the magic T to feed the antenna, it is difficult to suppress the side lobe deterioration.

  An object of the present invention is to solve the above-mentioned problems and to provide an array antenna capable of suppressing side lobe deterioration even when used in a wide band.

The present invention is an array antenna comprising: a first sub-array including a plurality of radiating elements; and a second sub-array including a plurality of radiating elements disposed on a substrate, and a feed line feeding the radiating elements.
A magic T is provided in the middle of the feed line from the excitation source to the first and second subarrays, and a signal from the excitation source is input to the E port of the magic T, and the input signal is H of the magic T A plurality of radiation elements, which are output from two other ports than the port, are fed from a first direction to a plurality of radiation elements included in the first subarray, and a plurality of radiation elements included in the second subarray are the first It is an array antenna characterized by feeding from a second direction opposite to the direction.

Further, according to the present invention, there is provided an array antenna comprising: a first sub-array including a plurality of radiating elements; and a second sub-array including a plurality of radiating elements disposed on a substrate, and a feed line feeding the radiating elements.
A signal from an excitation source is input to a rat race circuit, a terminal adjacent to a terminal to which the signal is input is connected to the first subarray, and a terminal in reverse phase to the adjacent terminal is the second one. Connect to the sub array,
The plurality of radiating elements included in the first sub-array is fed from a first direction, and the plurality of radiating elements included in the second sub-array is fed from a second direction opposite to the first direction It is an array antenna characterized by the above.

  According to the array antenna of the present invention, it is possible to suppress the side lobe deterioration even when used in a wide band.

It is a schematic diagram explaining the array antenna 100 of the 1st Embodiment of this invention. It is a figure which shows the simulation result of the radiation pattern of the azimuth direction of the array antenna 100 of the 1st Embodiment of this invention. It is a schematic plan view explaining the array antenna fed from the same direction to a radiating element. It is a figure which shows the simulation result of the radiation pattern of the azimuth direction of the array antenna which feeds a radiation | emission element from the same direction. It is a figure which shows the simulation result of the radiation pattern in the frequency which shifted | deviated 4% from center frequency about the array antenna 100 of FIG. It is a figure which shows the simulation result of the radiation pattern in the frequency which shifted | deviated similarly 4% from center frequency when not using magic T by the array antenna 100 of FIG. It is a schematic plan view which shows the array antenna 400 of the 2nd Embodiment of this invention. It is a figure which shows the rat race circuit used with the array antenna of the 3rd Embodiment of this invention. It is a schematic diagram explaining the array antenna of the 3rd Embodiment of this invention. It is a schematic plan view for demonstrating the array antenna of the 4th Embodiment of this invention.

First Embodiment
FIG. 1 is a schematic view illustrating an array antenna 100 according to a first embodiment of the present invention. The first sub array 131 and the second sub array 132 are arranged in line symmetry on the printed circuit board 110. The first subarray 131 and the second subarray 132 are fed in the reverse direction.

  The first subarray 131 will be described. Four radiation elements 101 are disposed on the printed circuit board 110 to form two four-element arrays 121 and 122. The fact that there are four elements in itself has no meaning, and "four-element array" is a name for convenience. The radiation element 101 is a patch antenna formed by a rectangular conductor pattern, and is connected to the feed line 102 at one place of the conductor pattern. The feed line 102 is a microstrip line. A four-element array 122 having the same configuration as that of the four-element array 121 is disposed adjacent to the printed circuit board 110, and the four-element arrays 121 and 122 constitute a first sub-array 131. All eight elements constituting the first sub-array 131 are fed from the left side of FIG.

  A first signal input / output port 141 which is a feeding point is provided at the end of the printed circuit board 110, and eight radiating elements 101 of the first sub-array 131 in a tournament type layout through the feeding line 151 between the four element arrays 121 and 122. Wire up to the same length to feed. The first sub-array 131 is fed in parallel from the first signal input / output port 141 to the radiation elements 101. In addition, the second sub-arrays 133 are fed in parallel from the second signal input / output port 142 to the respective radiation elements 101 '.

  The second subarray 132 will now be described. Four radiation elements 101 ′ are disposed on the printed circuit board 110 to form two four-element arrays 123 and 124. The radiation element 101 ′ is a patch antenna formed of a rectangular conductor pattern, and is connected to the feed line 103 at one place of the conductor pattern. The feed line 103 is a microstrip line. A 4-element array 124 having the same configuration as that of the 4-element array 123 is disposed adjacent to the printed circuit board 110, and the 4-element arrays 123 and 124 constitute a second sub-array 132. All eight elements constituting the second subarray 132 are fed from the right side of FIG.

  Thus, in the first sub-array 131, the feed lines 102 are connected on the left side of each radiation element 101, and in the second sub-array 132, the feed lines 102 are connected on the right side of each radiation element 101 '. Located on the side.

  A second signal input / output port 142 serving as a feeding point is provided at the end of the printed circuit board 110 opposite to the first signal input / output port 141, and a tournament is conducted between the four element arrays 123 and 124 through the feed line 152. The eight radiating elements 101 'of the second subarray 132 are wired equal length and fed in a mold layout.

  The first subarray 131 and the second subarray 132, including the feed lines 102 and 103, are line symmetrical with respect to a straight line 140 (dotted-dotted line) between the first subarray 131 and the second subarray 132 as a symmetry axis. It is arranged. The straight line 140 is a line orthogonal to the line connecting the first signal input / output port 141 and the second signal input / output port 142, and is not actually formed on the printed circuit board 110, but for the sake of explanation. It is a straight line assumed.

  The transmission source from the excitation source 160, that is, the transmitter is guided by a waveguide (not shown), and the waveguide is connected to the E port 171 (wide wall) of the magic T 170. The transmission signal input from the E port 171 is distributed within the magic T, and is output in opposite phase to the other two ports 172 and 173 other than the E port and the H port.

  The ports 172 and 173 of the magic T 170 are respectively connected to waveguides (not shown), one waveguide is connected to the first signal input / output port 141, and the other waveguide is connected to the second signal input. It is connected to the output port 142. The radiation element 101 is fed via the feed line 151 or the feed line 152.

  In the radiation element 101 of the first subarray 131 and the radiation element 101 ′ of the second subarray 132, the feed directions are opposite to each other. In FIG. 1, this is expressed as "in-phase" or "in-phase".

  On the other hand, the transmission signals transmitted from the magic T 170 to the first signal input / output port 141 and the second signal input / output port 142 have opposite phases to each other as described above. The radiation element 101 and the radiation element 101 'can be excited in opposite directions by the fact that the radiation elements are fed in the opposite directions to offset the asymmetry of the radiation pattern of the radiation element. The two sub-arrays are excited in opposite phase to each other by this alone, but in this embodiment, the transmission signals input to the two sub-arrays are also in anti-phase to each other. Therefore, the reverse phase x the reverse phase results in that the radiation element 101 and the radiation element 101 'are finally excited in phase. In other words, it is possible to excite the two sub-arrays in phase while canceling the asymmetry of the radiation pattern of the radiation element.

  Note that, unlike the usual case, the E port is used as a Σ port, and the H port is used as a Δ port. The usual magic T uses the E port as the Δ port and the H port as the Σ port, but in the present embodiment, the reverse is used. As a result, phase inversion can be performed over a wide band, and as a result, the side lobe degradation can be suppressed in a wide band.

  Also, the magic T has a small phase frequency characteristic, and the characteristic does not change much depending on the frequency. Therefore, it is suitable for broadband applications.

  The above is the operation at the time of transmission, but when the array antenna 100 receives a signal, the received signal propagates in the reverse direction of the feed line from the transmission and is input to the two ports 172 and 173 of the magic T. A receiver (not shown) is connected to the H port 174.

  If the feed direction of the radiation element is reversed between two subarrays as shown in FIG. 1, and the first signal input / output port 141 and the second signal input / output port 142 are added in reverse phase, the azimuthal direction in FIG. As shown in the simulation result of the radiation pattern of (1), it can be seen that the radiation patterns are symmetrical on the left and right, and low side lobe can be realized.

  Here, as shown in FIG. 3, an array antenna 350 is disposed such that power is supplied from the left direction in the same direction, that is, to the same direction, to the respective radiation elements of the first subarray 131 'and the second subarray 132' of FIG. think of. In FIG. 3, this is expressed as "in-phase" or "in-phase". The first signal input / output port 141 'and the second signal input / output port 142' are located opposite each other across the first and second subarrays 131 'and 132' as in FIG. The simulation result of the radiation pattern in the azimuthal direction of the array antenna in the case of such an arrangement is as shown in FIG.

  Next, radiation patterns at frequencies shifted from the center frequency will be described. FIG. 5 is a simulation result of a radiation pattern at a frequency shifted 4% from the center frequency for the array antenna 100 of FIG. On the other hand, FIG. 6 is a simulation result of a radiation pattern at a frequency 4% off the center frequency when the magic T is not used in the array antenna 100 of FIG.

  Specifically, FIG. 6 shows that only one of the feed lines from the excitation source to the first signal input / output port 141 or one of the feed lines from the excitation source to the second signal input / output port 142, The first signal input / output port 141 and the second signal input / output port 142 are in reverse phase by inserting a delay circuit for delaying by λ / 2 (half wavelength). Here, λ is a wavelength corresponding to the center frequency of the frequency band to be used. The subarray itself is the same as in FIG.

  In the radiation pattern of FIG. 5, it can be seen that the side lobes of the radiation pattern are equal at the left and right even when the center frequency is shifted when the band is wide. In the radiation pattern of FIG. 6 as well, if the center frequency, the signals of the opposite phase are completely in phase by the delay circuit. However, as the bandwidth is wider and the distance from the center frequency increases, the phase difference between the left half sub-array and the right half sub-array increases, and the side lobes of the radiation pattern become noticeable.

  As described above, in the present embodiment, when power is supplied from one direction (first direction) to the radiation elements of one sub array, the other sub array is supplied power from the opposite direction (second direction). In addition, power is supplied to the two subarrays in opposite phases. As a result, the radiation pattern of the array antenna can be made symmetrical and low side lobe can be realized.

In the present embodiment, the straight line 140 of the boundary between the first subarray 131 and the second subarray 132 is disposed in line symmetry with the symmetry axis. However, the arrangement in line symmetry is not essential, as long as the radiating element 101 is fed from the first direction and the radiating element 101 ′ is fed from the opposite second direction. Further, in the present embodiment, the second signal input / output port 142 is provided on the printed board 110 on the opposite side of the first signal input / output port 141 across the first and second sub arrays. However, for the same reason, such a positional relationship is not necessary. For example, the positional relationship may be 90 degrees on a printed circuit board.
Second Embodiment
FIG. 7 is a schematic plan view showing an array antenna 400 according to the second embodiment of the present invention. In this array antenna 400, two array antennas 100 described in FIG. 1 are arranged on a printed circuit board. These are referred to as an array antenna 200 and an array antenna 300. Power is supplied to a first magic T 301 provided to the array antenna 200 and a second magic T 302 provided to the array antenna 300. As in the first embodiment, the E port is used as the Σ port, and the H port is used as the Δ port. The transmission signals input to the E ports 171 and 171 'of the first and second magics T301 and 302, respectively, are distributed within the two magics T301 and 302, and output in opposite phases to the two ports possessed by each magic T. Be done. The two ports are respectively connected to waveguides, one waveguide is connected to a first signal input / output port, and the other waveguide is connected to a second signal input / output port. From there, each radiation element is fed via the feed line on the printed circuit board.

  The third magic T 303 is placed between the excitation source 960 and the first and second magics T 301 and 302 are fed from there. The third magic T 303 uses the E port as the Δ port and the H port as the Σ port as in the normal usage. That is, the transmission signal from the excitation source 960 is input to the H port 974 of the third magic T 303. The input signal is output from the two ports 972 and 973 of the third magic T 303 as an in-phase signal, and is input to the E ports 171 and 171 'of the two magic T 301 and 302, respectively, in the same phase.

When the array antenna of this embodiment is used, it is possible to perform monopulse tracking in the lateral direction with respect to the flying object or the like.
Third Embodiment
Although the magic T is used in the first and second embodiments, a rat race circuit 501 can also be used. The rat race circuit, as shown in FIG. 8, is a ring connection of three 1⁄4 wavelength transmission lines and a 3⁄4 wavelength transmission line. It is possible to perform reverse phase distribution. In the rat race circuit 501, the 1⁄4 wavelength transmission line and the 3⁄4 wavelength transmission line are formed by coaxial lines. A quarter wavelength transmission line is connected between the terminals 502 and 503, between the terminals 503 and 504, and between the terminals 504 and 505 in FIG. 8; and 3/4 wavelength between the terminals 5050 and 502. Connect by transmission line. The two sub array antennas are the same as in the first and second embodiments.

  The signal input from the terminal 502 is reverse-phase distributed to the terminals 503 and 505, and is not output from the terminal 504. The signal input from the terminal 503 is in-phase distributed to the terminals 502 and 504 and is not output from the terminal 505.

  FIG. 9 is a schematic view of an array antenna using the rat race circuit of this embodiment. As shown in FIG. 9, the transmission signal from the excitation source 160 is input to the terminal 502 of the rat race circuit 501. The terminal 503 adjacent to the terminal 502 is connected to the feed line 151, and the feed line 151 is connected to the first signal input / output port 141 of the first subarray 131. On the other hand, the terminal 505 of the rat race circuit 501 in reverse phase to the terminal 503 is connected to the feed line 152, and the feed line 152 is connected to the second signal input / output port 142 of the second subarray 132.

  In this way, signals of opposite phases can be input to the feed points of the first and second subarrays. As a result, the plurality of radiation elements 101 included in the first sub-array 131 is fed from the first direction, and the plurality of radiation elements 101 ′ included in the second sub-array 132 is in the second direction opposite to the first direction. Powered by The terminals 503 and 505 of the negative phase output are also connected to the receiver.

The signal from the excitation source 160 may be input to the terminal 505, in which case the terminal 504 adjacent to the terminal 505 is connected to the feed line 151, and the terminal 502 in reverse phase to the terminal 504 is connected to the feed line 152. You just have to connect.
Fourth Embodiment
FIG. 10 is a schematic plan view for explaining an array antenna according to a fourth embodiment of the present invention. A first sub-array 610 including a plurality of radiation elements 601 and a second sub-array 620 including a plurality of radiation elements 602 are disposed, and include feed lines 631 and 632 for feeding the respective radiation elements. A magic T 670 is provided in the middle of the feed line from the excitation source 680 to the first and second sub-arrays, a signal from the excitation source 680 is input to the E port 671 of the magic T 670, and the input signal is the H port of the magic T 670 The other two ports 672 and 673 except 674 output the signals in antiphase with each other.

  In FIG. 9, the feed lines 631 and 632 are displayed only at places near the first and second feed points, and the display is omitted at places near the radiation elements.

The radiating elements 601 of the first subarray 610 and the radiating elements 602 of the second subarray 620 are fed in opposite directions. In addition, transmission signals transmitted to the first feeding point 650 and the second feeding point 660 by the magic T 670 are out of phase with each other. As a result, the radiating elements 601 and 602 are excited in phase. That is, although the radiating element 601 and the radiating element 602 are excited in opposite directions due to the opposite direction of power feeding, the transmission signals input to the two feeding points are in antiphase x antiphase because they are in antiphase. Eventually, the radiating element 601 and the radiating element 602 will be excited in phase. Therefore, it is possible to suppress the side lobe deterioration even when used in a wide band.
(Other embodiments)
In the first and second embodiments, the array antennas are all two-dimensional arrays, but the present invention is also applicable to linear arrays.

The present invention can be used for the following antennas and radars.
Antennas or radars where the input power is high and it is necessary to use a waveguide circuit to avoid discharge.
An antenna or radar that requires low side lobes over a wide band.
An antenna or radar in which unnecessary radiation from the feed line is affected by the radiation pattern with a polarization sharing antenna such as left / right circular polarization, orthogonal linear polarization, etc.

100, 200, 300, 400, 600 Array antenna 101, 101 ', 601, 602 Radiating element 102, 103, 151, 152 Feeding line 110, 710 Printed circuit board 121, 122, 123, 124 4-element array 131, 131' 1 sub array 132, 132 '620 second sub array 140, 140' straight line 141 first signal input / output port 142 second signal input / output port 160, 680 excitation source 170, 670 Magic T
171,671 E port 172,173,672,673 port 301 first magic T
302 Second Magic T
303 Third Magic T
501 rat race circuit 502, 503, 504 terminal 610 first sub array 620 second sub array 631, 632 feed line 650 first feed point 660 second feed point

Claims (7)

An array antenna comprising: a first sub-array including a plurality of radiating elements; and a second sub-array including a plurality of radiating elements disposed on a substrate and comprising a feed line for feeding the radiating elements,
A magic T is provided in the middle of the feed line from the excitation source to the first and second subarrays, and a signal from the excitation source is input to the E port of the magic T, and the input signal is H of the magic T A plurality of radiation elements, which are output from two other ports than the port, are fed from a first direction to a plurality of radiation elements included in the first subarray, and a plurality of radiation elements included in the second subarray are the first An array antenna characterized in that power is fed from a second direction opposite to the direction.   The array antenna according to claim 1, wherein connection points of the radiation element and the feed line are provided on opposite sides of the first and second sub-arrays.   The array antenna according to claim 1 or 2, wherein an E port of the magic T is used as a Σ port and an H port is used as a Δ port.   The array according to any one of claims 1 to 3, wherein the first and second subarrays are arranged in line symmetry with a boundary between the first and second subarrays as a symmetry axis. antenna. A first magic T of the first array antenna and the first array antenna, wherein at least two array antennas according to any one of claims 1 to 4 are arranged as a first array antenna and a second array antenna. An array antenna fed from a third magic T to a second magic T of the two array antennas,
The signal from the excitation source is input as an in-phase signal to two ports other than the E port and the H port of the third magic T, and the input signal is output from the H port of the third magic T Array antenna input to the first magic T and the second magic T; An array antenna comprising: a first sub-array including a plurality of radiating elements; and a second sub-array including a plurality of radiating elements disposed on a substrate and comprising a feed line for feeding the radiating elements,
A signal from an excitation source is input to a rat race circuit, and a terminal of the rat race circuit adjacent to a terminal to which the signal is input is connected to the first subarray and is in reverse phase to the adjacent terminal. Connect a terminal to the second subarray,
The plurality of radiating elements included in the first sub-array is fed from a first direction, and the plurality of radiating elements included in the second sub-array is fed from a second direction opposite to the first direction Array antenna characterized by   The array antenna according to any one of claims 1 to 6, wherein the radiation elements are fed in parallel from the first feeding point of the first subarray and the second feeding point of the second subarray.

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