JP6988278B2 - Array antenna - Google Patents

Description

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

An array antenna arranges multiple radiation elements in a linear, planar, curved shape, etc., excites all or part of them, and controls the excitation current (voltage) and phase to achieve the desired radiation directivity (radiation pattern). Is an antenna to get.

When radiating radio waves from an array antenna, a feeding circuit is used to excite individual radiating elements that make up the array antenna. Radiating elements are arranged on a printed circuit board or the like, and individual radiating elements are connected to a feeding circuit by a feeding line. If the board is rectangular, normally, a connection portion between a power supply line and a power supply circuit is provided on one side of the board, and power is supplied to the radiating element from there.

The array antenna device of Patent Document 1 includes a first substrate provided with a first feeding point, and a second substrate laminated below the first feeding point and provided with a second 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 radiating element array in which a plurality of second radiating elements are arranged in an array is formed on the second substrate. A first feeding line for feeding power to the first radiating element array is formed on the first substrate. The first feeding line has a pattern of equal length for each of the first feeding point and the plurality of first radiating elements so that the plurality of first radiating elements form linearly polarized waves in the first polarization direction. Connect with wiring.

Further, a second feeding line for feeding power to the second radiating element array is formed on the second substrate. The second feeding line has a second feeding point and a plurality of second feeding points so that the plurality of second radiating elements form a linear polarization in the second polarization direction orthogonal to the first polarization direction. Connect each of the radiation elements of the above with a pattern wiring of the same length. A wireless signal is output to the 180-degree hybrid circuit from the port on the transmitter side, and power is supplied to the first and second feeding points with a phase difference of 180 degrees.

By doing so, it is possible to form linearly polarized waves at a predetermined angle while suppressing side lobes without meandering the feeding line. (Paragraphs (0006), (0028), FIG. 2)
Further, in the planar antenna of Patent Document 2, in a planar antenna having a configuration in which power is supplied in parallel by a waveguide, a magic T is configured in a synthesis unit, and each waveguide circuit is configured by blocks and stacked. In the examples of FIGS. 1 and 2, the antenna block B is formed by forming the antenna element 1 of four elements on the antenna circuit board 2 by forming the aperture on the metal plate. A feeding waveguide opening 3 is formed on the bottom surface of the antenna block B, and the feeding waveguide opening 3 is in-phase composite waveguide via an L-shaped corner 4 configured in the in-phase composite feeding block B0. It is output to the tube 5. The outputs of the horizontally adjacent 4-element arrays are homeomorphically synthesized by the first T-branch T1 via the in-phase synthetic waveguide 5, and further combined with the composite output of the vertically adjacent antenna elements by the second T-branch T2. In the end, the common mode combined power of 16 elements in total, that is, the sum pattern of monopulses is obtained as the common mode combined output Σ (paragraph (0007), FIGS. 1 and 2).

International Publication No. 2015/1209089 Japanese Unexamined Patent Publication No. 6-252683

However, in Patent Document 1, as is clear from FIG. 2, the power is supplied from the same direction to the plurality of radiating elements 101, 201 or 102, 202 arranged on one substrate 1 or the substrate 2. That is, in the radiating elements 101 and 201 on the substrate 1, all the connection points where the feeder lines are connected to the individual radiating elements are on the back side of the radiating element, and the feeding is performed in the direction from the back to the front in FIG. Similarly, the feeding directions for the radiating elements 102 and 202 on the substrate 2 are all directions from the front to the back in the figure. The same applies to the other FIGS. 1, 3 and 4 in Patent Document 1.

Due to the influence of the feeding line connected to the radiating element, the radiating characteristics of each radiating element become asymmetric. Since the array antenna radiation pattern is the radiation pattern of the radiation element multiplied by the array factor (directivity determined by the arrangement of the radiation element), if the radiation pattern of the radiation element is asymmetric, the radiation pattern of the array antenna will also be asymmetric. Become. That is, the side lobes become asymmetric. Patent Document 1 does not provide a solution to this point.

When the feeding line must be configured on the same side as the radiating element with respect to the ground surface, it is effective to suppress the side lobes if the direction of feeding the radiating element is symmetrical with respect to the central axis. However, there was a drawback that half of the array was out of phase. It is possible to electrically match the phase using a delay circuit that delays this by half a wavelength, and if the band used is narrow, the phase can be matched by that method. However, when the band is wide, the phases are not aligned at the edges of the band, and the side lobes deteriorate.

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 supply power to the antenna, it is difficult to suppress the deterioration of the side lobe.

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

The present invention is an array antenna in which a first sub-array containing a plurality of radiating elements and a second sub-array containing a plurality of radiating elements are arranged on a substrate and provided with a feeding line for feeding the radiating elements.
A magic T is provided in the middle of the feeding line from the excitation source to the first and second sub-arrays, a signal from the excitation source is input to the E port of the magic T, and the input signal is the H of the magic T. Output from two ports other than the port, power is supplied from the first direction to the plurality of radiating elements included in the first sub-array, and the plurality of radiating elements included in the second sub-array are the first. It is an array antenna, characterized in that power is supplied from a second direction opposite to the direction.

Further, the present invention is an array antenna in which a first sub-array including a plurality of radiating elements and a second sub-array including a plurality of radiating elements are arranged on a substrate and provided with a feeding line for feeding the radiating elements.
The signal from the excitation source is input to the rat race circuit, the terminal adjacent to the terminal to which the signal is input is connected to the first subarray, and the terminal having the opposite phase to the adjacent terminal is the second terminal. Connect to the subarray and
The plurality of radiating elements included in the first sub-array are fed from the first direction, and the plurality of radiating elements included in the second sub-array are fed from the second direction opposite to the first direction. It is an array antenna characterized by this.

According to the array antenna of the present invention, deterioration of side lobes can be suppressed 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 in the azimuth direction of the array antenna 100 of 1st Embodiment of this invention. It is a schematic plan view explaining the array antenna which feeds a radiating element from the same direction. It is a figure which shows the simulation result of the radiation pattern in the azimuth direction of the array antenna which feeds a radiation element from the same direction. It is a figure which shows the simulation result of the radiation pattern at the frequency deviated by 4% from the center frequency about the array antenna 100 of FIG. It is a figure which shows the simulation result of the radiation pattern at the frequency which also deviated by 4% from the center frequency in the array antenna 100 of FIG. 1 when the magic T is not used. 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 in 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 diagram 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 line-symmetrically on the printed circuit board 110. Further, the first sub-array 131 and the second sub-array 132 are fed in opposite directions.

The first sub-array 131 will be described. Four radiating elements 101 are arranged on the printed circuit board 110 to form two four-element arrays 121 and 122. It should be noted that the use of four elements is meaningless, and the "four-element array" is a name for convenience. The radiating element 101 is a patch antenna formed of a rectangular conductor pattern, and is connected to the feeding line 102 at one place of the conductor pattern. The feeding line 102 is a microstrip line. A 4-element array 122 having the same configuration as the 4-element array 121 is arranged adjacent to the printed circuit board 110, and the 4-element array 121 and 122 form 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 a feeding line 151 is passed between the four element arrays 121 and 122. Wire to the same length to supply power. The first sub-array 131 is fed in parallel to each radiating element 101 from the first signal input / output port 141. Further, the second sub-array 133 is fed in parallel from the second signal input / output port 142 to each radiating element 101'.

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

As described above, in the first sub-array 131, the feeding line 102 is connected on the left side of each radiating element 101, and in the second sub-array 132, the feeding line 102 is connected on the right side of each radiating element 101', and the connection points are opposite to each other. Located on the side.

A second signal input / output port 142, which is a feeding point, is provided at the end of the printed circuit board 110 opposite to the first signal input / output port 141, and the tournament is passed through the feeding line 152 between the four element arrays 123 and 124. In the layout of the mold, the eight radiating elements 101'of the second sub-array 132 are wired to the same length to supply power.

The first sub-array 131 and the second sub-array 132, including the feeding lines 102 and 103, are line-symmetrical with the straight line 140 (dashed-dotted line) between the first sub-array 131 and the second sub-array 132 as the axis of symmetry. Have been placed. 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 board 110, but for explanation. It is an assumed straight line.

The excitation source 160, that is, the transmission signal from the transmitter is guided by a waveguide (not shown), and the waveguide is connected to the E port 171 (wide wall surface) of the magic T170. The transmission signal input from the E port 171 is distributed in the magic T, and is output to the other two ports 172 and 173 other than the E port and the H port in opposite phase.

The ports 172 and 173 of the Magic T170 are connected to a waveguide (not shown), respectively, one waveguide is connected to the first signal input / output port 141, and the other waveguide is a second signal input. Connected to output port 142. Power is supplied to the radiating element 101 via the power supply line 151 or the power supply line 152.

In the radiating element 101 of the first sub-array 131 and the radiating element 101'of the second sub-array 132, the directions of feeding are opposite to each other. In FIG. 1, it is expressed as "in-phase" and "reverse-phase".

On the other hand, the transmission signals transmitted from the magic T170 to the first signal input / output port 141 and the second signal input / output port 142 are out of phase with each other as described above. Since the directions in which power is supplied to the radiating element are opposite, the radiating element 101 and the radiating element 101'are excited in opposite directions, and the asymmetry of the radiating pattern of the radiating element can be offset. This alone excites the two sub-arrays in opposite phases, but in the present embodiment, the transmission signals input to the two sub-arrays are in opposite phases to each other. Therefore, the phase is reversed × the phase is reversed, and finally the radiating element 101 and the radiating element 101 ′ are excited in the same phase. That is, the two subarrays can be excited in the same phase while canceling out the asymmetry of the radiation pattern of the radiation element.

Unlike usual, the E port is used as the Σ port and the H port is used as the Δ port. In the normal magic T, the E port is used as the Δ port and the H port is used as the Σ port, but in the present embodiment, they are used in reverse. As a result, phase inversion can be performed over a wide band, and as a result, deterioration of side lobes can be suppressed over a wide band.

Further, 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 wideband applications.

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

As shown in FIG. 1, when the feeding directions of the radiating elements are reversed between the two subarrays and the first signal input / output port 141 and the second signal input / output port 142 are added in opposite phases, the azimuth direction is shown in FIG. As shown in the simulation result of the radiation pattern of, it can be seen that the radiation pattern is symmetrical on the left and right, and low side lobe can be realized.

Here, as shown in FIG. 3, the array antenna 350 is arranged to supply power to each radiating element of the first sub-array 131'and the second sub-array 132' in FIG. 1 from the same direction, that is, from the left direction in the figure. think of. In FIG. 3, it is expressed as "in-phase" and "in-phase". The first signal input / output port 141'and the second signal input / output port 142' are located opposite to each other with the first and second subarrays 131'and 132', as in FIG. 1. The simulation result of the radiation pattern in the azimuth direction of the array antenna in such an arrangement is as shown in FIG. 4, and the left and right sides are asymmetrical.

Next, the radiation pattern at a frequency deviated from the center frequency will be described. FIG. 5 is a simulation result of the radiation pattern of the array antenna 100 of FIG. 1 at a frequency deviated from the center frequency by 4%. On the other hand, FIG. 6 is a simulation result of a radiation pattern at a frequency also deviated from the center frequency by 4% in the array antenna 100 of FIG. 1 without using the magic T.

Specifically, FIG. 6 shows only one of the power supply lines between the excitation source and the first signal input / output port 141, or the power supply line between the excitation source and the second signal input / output port 142. A delay circuit that delays λ / 2 (half wavelength) is inserted to reverse the phase of the first signal input / output port 141 and the second signal input / output port 142. Note that λ is a wavelength corresponding to the center frequency of the frequency band used. The subarray itself is the same as in FIG.

It can be seen that in the radiation pattern of FIG. 5, when the band is wide, the side lobes of the radiation pattern are equal on the left and right even if the center frequency shifts. Even in the radiation pattern of FIG. 6, if the center frequency is used, the signals having opposite phases are completely in phase in the delay circuit. However, as the band is wide and the distance from the center frequency increases, the phase difference between the left half sub-array and the right half sub-array becomes large, and the unevenness of the side lobes of the radiation pattern becomes conspicuous.

As described above, in the present embodiment, when power is supplied to the radiating element of one sub-array from a direction (first direction), power is supplied to the other sub-array from the opposite direction (second direction). In addition, the two subarrays are fed in opposite phase to each other. By doing so, the radiation pattern of the array antenna can be made symmetrical and low side lobes can be realized.

In this embodiment, the straight line 140 of the boundary line between the first sub-array 131 and the second sub-array 132 is arranged line-symmetrically with the straight line 140 as the axis of symmetry. However, it is not essential to arrange them line-symmetrically, and it is sufficient that 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 circuit board 110 on the opposite side of the first signal input / output port 141 with the first and second subarrays interposed therebetween. However, for the same reason, it is not necessary to have such a positional relationship, and for example, the positional relationship may be 90 degrees on the printed circuit board.
(Second embodiment)
FIG. 7 is a schematic plan view showing the 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 the first magic T301 provided in the array antenna 200 and the second magic T302 provided in 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 signal input to the respective E ports 171 and 171'of the first and second magic T301 and 302 is distributed in the two magic T301 and 302, respectively, and output to the two ports of each magic T in opposite phase. Will be done. The two ports are each connected to a waveguide, one waveguide is connected to the first signal input / output port, and the other waveguide is connected to the second signal input / output port. From there, power is supplied to each radiating element via the power supply line on the printed circuit board.

A third magic T303 is placed between the excitation source 960 and the first and second magic T301s and 302s to supply power from the third magic T303. The third magic T303 uses the E port as the Δ port and the H port as the Σ port in the same way as in normal usage. That is, the transmission signal from the excitation source 960 is input to the H port 974 of the third magic T303. The input signal is output as an in-phase signal from the two ports 972,973 of the third magic T303, and is input to the E ports 171 and 171'of the two magic T301 and 302 in the same phase with each other.

When the array antenna of the present embodiment is used, lateral monopulse tracking with respect to a flying object or the like becomes possible.
(Third embodiment)
Although the magic T is used in the first and second embodiments, a rat race circuit 501 can also be used. As shown in FIG. 8, the rat race circuit is formed by connecting three 1/4 wavelength transmission lines and a 3/4 wavelength transmission line in a ring shape, and like the Magic T, it can be distributed in phase by selecting an input terminal. Reversed phase distribution can be performed. The rat race circuit 501 is composed of a 1/4 wavelength transmission line and a 3/4 wavelength transmission line as a coaxial line. In FIG. 8, the terminals 502 and 503, the terminals 503 and 504, the terminals 504 and the terminal 505 are all connected by a 1/4 wavelength transmission line, and the terminals 5050 and the terminal 502 are connected by a 3/4 wavelength. Connect with a 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 distributed in reverse phase to the terminals 503 and 505, and is not output from the terminal 504. Further, the signal input from the terminal 503 is distributed in phase to the terminals 502 and 504, and is not output from the terminal 505.

FIG. 9 is a schematic diagram of an array antenna using the rat race circuit of the present 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 feeding line 151, and the feeding 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 having the opposite phase to the terminal 503 is connected to the feeding line 152, and the feeding line 152 is connected to the second signal input / output port 142 of the second subarray 132.

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

The signal from the excitation source 160 may be input to the terminal 505. In that case, the terminal 504 adjacent to the terminal 505 is connected to the feeding line 151, and the terminal 502 having the opposite phase to the terminal 504 is connected to the feeding line 152. Just connect.
(Fourth Embodiment)
FIG. 10 is a schematic plan view for explaining the array antenna of the fourth embodiment of the present invention. A first sub-array 610 including a plurality of radiating elements 601 and a second sub-array 620 including a plurality of radiating elements 602 are arranged, and a feeding line 631, 632 for supplying power to each radiating element is provided. A magic T670 is provided in the middle of the feeding 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 T670, and the input signal is the H port of the magic T670. It is output from two ports 672 and 673 other than 674 in opposite phases to each other.

In FIG. 9, the feeding lines 631 and 632 are displayed only at places near the first and second feeding points, and the display is omitted at places near each radiating element.

In the radiating element 601 of the first sub-array 610 and the radiating element 602 of the second sub-array 620, the feeding directions are opposite to each other. Further, the transmission signals transmitted to the first feeding point 650 and the second feeding point 660 by the magic T670 are out of phase with each other. As a result, the radiating elements 601 and 602 are excited in the same phase. That is, the radiating element 601 and the radiating element 602 are excited in opposite directions due to the opposite directions of feeding, but since the transmission signals input to the two feeding points are in opposite phase, it becomes reverse phase × reverse phase. Eventually, the radiating element 601 and the radiating element 602 are excited in the same phase. Therefore, deterioration of the side lobe can be suppressed 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 can also be applied to linear arrays.

The present invention can be used for the following antennas and radars.
-Antennas or radars that have a large input power and require the use of a waveguide circuit to avoid discharge.
-Antennas or radars that require low sidelobes over a wide band.
-An antenna or radar that is a polarized wave shared antenna such as left-right circularly polarized wave and orthogonal linearly polarized wave, and unnecessary radiation from the feeding line is affected by the radiation pattern.

100,200,300,400,600 Array antenna 101, 101', 601,602 Radiation element 102, 103, 151,152 Feed line 110,710 Printed circuit board 121, 122, 123, 124 4 element array 131, 131' 1 sub-array 132, 132'620 2nd sub-array 140,140'straight line 141 1st signal input / output port 142 2nd 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 Terminals 610 First Subarray 620 Second Subarray 631,632 Feed Line 650 First Feed Point 660 Second Feed Point

Claims (7)

An array antenna in which a first sub-array containing a plurality of radiating elements and a second sub-array containing a plurality of radiating elements are arranged on a substrate and a feeding line for feeding the radiating elements is provided.
A magic T is provided in the middle of the feeding line from the excitation source to the first and second sub-arrays, a signal from the excitation source is input to the E port of the magic T, and the input signal is the H of the magic T. is output from the other two ports other than port, power is supplied from a first direction relative to the sides of the plurality of radiating elements the first sub-array includes a plurality of radiating elements the second sub-array includes array antenna for the second direction before Symbol first direction and the opposite direction to the sides of, the power supply to the first sub-array, characterized in that the feeding in opposite phase. The array antenna according to claim 1, wherein the connection point between the radiating element and the feeding line is provided on opposite sides of the first and second sub-arrays. The array antenna according to claim 1 or 2, wherein the E port of the magic T is used as a Σ port and the H port is used as a Δ port. The array according to any one of claims 1 to 3, wherein the first and second sub-arrays are arranged line-symmetrically with the boundary line between the first sub-array and the second sub-array as an axis of symmetry. antenna. The first magic T of the first array antenna and the first magic T of the first array antenna are arranged by arranging at least two of the array antennas according to any one of claims 1 to 4 as a first array antenna and a second array antenna. It is an array antenna that supplies power from the third magic T to the second magic T of the second array antenna.
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. An array antenna input to the first magic T and the second magic T. An array antenna in which a first sub-array containing a plurality of radiating elements and a second sub-array containing a plurality of radiating elements are arranged on a substrate and a feeding line for feeding the radiating elements is provided.
The signal from the excitation source is input to the rat race circuit, the terminal of the rat race circuit adjacent to the terminal to which the signal is input is connected to the first subarray, and the phase is reversed with respect to the adjacent terminal. Connect the terminals to the second subarray and
Power is supplied from the first direction to the sides constituting the plurality of radiating elements included in the first sub-array, and the first direction with respect to the sides constituting the plurality of radiating elements included in the second sub-array. An array antenna characterized in that power is supplied from a second direction in the opposite direction. The array antenna according to any one of claims 1 to 6, wherein parallel feeding is performed from the first feeding point of the first sub-array and the second feeding point of the second sub-array to the radiating element.

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