JP3782278B2 - Beam width control method of dual-polarized antenna - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a polarization sharing antenna useful for a polarization diversity communication system that performs high-reliability communication using two radio waves having different planes of polarization, such as horizontal polarization and vertical polarization. The present invention provides a beam width control method for a dual-polarized antenna suitable for a mobile communication base station antenna or the like that requires a change in beam width in order to change the antenna directivity according to the area.
[0002]
[Prior art]
An example of a conventional typical dual-polarized antenna will be described based on references.
[0003]
FIG. 10 is a block diagram of the polarization diversity base station antenna shown in Reference 1 [Kyohei Fujimoto, “A Illustrated Mobile Communication Antenna System”, General Electronic Publishers, pp. 128, FIG. 4.26]. is there. In FIG. 10, 701 is a circular patch antenna as a radiating element, 702 is a horizontal polarization feeding point, 703 is a vertical polarization feeding point, 704 is a dielectric substrate, 705 is a radome, 706 is a parasitic element, 707 and 708 are A microstrip line 709, which is a feeding circuit, indicates a ground plane (conductor). In this antenna, a circular patch antenna 701 is used as a radiating element, which is fed by microstrip lines 707 and 708. Further, the parasitic element 706 is loaded to widen the antenna to cover the transmission / reception frequency band. Thereby, two orthogonal polarized waves can be transmitted and received independently by one radiating element. Further, the beam width can be changed in the range of 60 ° to 120 ° by appropriately setting the feeding phase for each element.
[0004]
FIG. 11 is a block diagram of an 800 MHz band wideband polarization antenna shown in Reference Document 2 [Proceedings of the IEICE General Conference B-53]. In FIG. 11, 801 is a reflector, 802 is a dipole element for vertical polarization, 803 is a dipole element for horizontal polarization, and 804, 805, and 806 are feed lines. The vertically polarized dipole element 802 and the horizontally polarized dipole element 803 are made of a thin aluminum plate. The element width of the vertically polarized dipole element 802 is adjusted to align the beam widths of vertically and horizontally polarized waves. The horizontally polarized dipole element 803 and the vertically polarized dipole element 802 are arranged so as to cross each other at the center. A parasitic element is arranged on the vertical dipole element to increase the bandwidth. The horizontal dipole element obtains the necessary bandwidth as it is.
[0005]
Figure 12 shows a reflector dipole with a deformed parasitic element arranged in Reference 3 [Shingo Moriyasu, Toru Matsuoka, Masayuki Nakano, Hiroyuki Arai, 1999 IEICE General Conference B1-150] Array antenna ". In FIG. 12, 901 is a printed circuit board, 902 is a dipole element, 903 is an array feed circuit, 904 is a back reflector, and 905 is a side reflector. To make the beam width about 80 °, the center distance of the dipole element is 0.325λ0 (λ0 is the free space wavelength at the design center frequency f0), and it is formed on one side of a dielectric substrate with a relative permittivity of 4.1 and thickness of 0.003λ0 I let you. In addition, a feed circuit including a parasitic element, a two-power distributor, and a Q transformer circuit is formed on the back surface of the microstrip transmission line.
[0006]
[Problems to be solved by the invention]
As shown in the example of the conventional antenna apparatus shown in FIG. 10, it is known that when a dual-polarized antenna is configured with one patch antenna, it is difficult to align the horizontal beam width with two polarized waves. . Since the physical dimensions of the antenna change depending on the material constant of the dielectric material filled in the antenna, it is possible to control the beam width using this phenomenon, but the controllable range is limited due to cost and other problems. There is. In addition, since the beam width of the patch antenna depends on the size of the ground plane, it must be designed in consideration of these. Furthermore, since the patch antenna is inherently a narrow band, a wide band is often achieved by loading a parasitic element. However, when a parasitic element is loaded, a high-order mode is excited in the antenna, which causes a problem that the isolation between polarized waves deteriorates.
[0007]
In the example of the conventional antenna device shown in FIG. 10, orthogonally fed patch antennas are also arranged in the horizontal direction in order to control the beam width in the horizontal plane, and they are all formed on a single printed board. . However, in an actual base station antenna, a metal mounting portion having sufficient strength is required for mounting on a steel tower or the like. In addition, since the strength of the antenna itself is insufficient with only the printed circuit board, an appropriately processed metal plate is often installed behind the printed circuit board. In the antenna device shown in FIG. 10, since the copper foil on the back surface of the printed circuit board operates as a reflecting plate, there arises a problem that the space between the mounting metal plate and the printed circuit board is wasted. In addition, in the antenna apparatus of FIG. 10, the beam width can be changed by controlling the phase of the adjacent feeding system. It becomes a problem.
[0008]
In the example of the conventional antenna apparatus shown in FIG. 11, the beam width control of the vertical polarization is possible, but the degree of freedom regarding the beam width control of the horizontal polarization is small. In addition, since a dipole element is used for vertically polarized waves, it is necessary to suppress radiation in the side surface direction of the antenna using a reflector or the like. When the reflector is not used, there is a problem that the beam width that can be realized is limited because the dipole element interval needs to be about half a wavelength in order to cancel the radiation in the horizontal direction. In addition, since the power supply line to the dipole element is installed perpendicular to the element and the back reflector, there is a problem that the structure becomes complicated when arrayed. Further, since the antenna element portion and the array feeding circuit are manufactured independently, there is a problem that the manufacturing cost is increased.
[0009]
Further, in the antenna device of FIG. 12, a branch circuit with an impedance conversion circuit is necessary to simultaneously excite two dipole elements by one-point feeding. This branch circuit needs to be completely arranged on the conductor band connecting the central part of each dipole element. In such a structure, since the antenna element and the array feeding circuit cannot be manufactured at the same time, it takes time and effort to increase the cost. In addition, there is a problem that a side reflector is required to arbitrarily control the beam width.
[0010]
[Means for Solving the Problems]
In order to solve the problems inherent in the conventional dual-polarized antenna as described above, the present invention is configured as follows.
(1) a third antenna and a fourth antenna that can excite different polarization B from the first antenna and a second antenna which can excite polarization A and polarization A, the antenna between different polarization Two sets of dual- polarized antenna arrays arranged in a row so as to be alternately adjacent to each other so that antennas of the same polarization plane are adjacent to each other on the same plane on different ground planes A method for controlling the beam width of a dual-polarized antenna arranged in parallel,
A dual-polarized antenna characterized by controlling the beam width in the direction orthogonal to the column direction of the dual-polarized antenna array by adjusting the interval between the two sets of dual-polarized antenna arrays on the separate ground planes Of beam width control method .
(2) In the configuration of (1), the feed lines of the first antenna and the second antenna are connected to the first coupling point, and the feed lines of the third antenna and the fourth antenna are the second. The first coupling point is connected to a first feeding means for exciting the polarization plane A, and the second coupling point is coupled to a second coupling point for exciting the polarization plane B. A configuration of a beam width control method of a dual-polarized antenna, characterized in that a feeding means is connected.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
In the following, preferred embodiments of the present invention will be described.
Example 1
FIG. 1 is a configuration diagram of an antenna apparatus according to a first embodiment of the present invention. Here, the present invention will be described based on a polarization-sharing array antenna device using vertical polarization and horizontal polarization.
[0012]
In FIG. 1, 1 and 2 are patch elements for vertical polarization, 3 and 4 are patch elements for horizontal polarization, 5 is a microstrip line as a feed line for the patch element 3 for horizontal polarization, and 6 is a horizontal polarization patch element. A microstrip line as a feed line for the wave patch element 4, a microstrip line as a feed line for the vertically polarized patch element 1, and 8 a feed line for the vertically polarized patch element 2. A microstrip line 9 is a dielectric substrate. The microstrip lines 5, 6, 7 and 8 are formed on the back surface of the dielectric substrate 9.
[0013]
In general, the electromagnetic wave radiated from the patch antenna is diffracted at the edge of the ground plane, but it is known that the influence varies depending on the polarization. Also, since the directivity of the patch antenna is different between the electric field surface and the magnetic field surface, when a dual-polarized antenna is configured, there arises a problem that the horizontal plane beam width does not match between the vertically polarized wave and the horizontally polarized wave. Therefore, an antenna that can design the beam width of the horizontally polarized wave and the vertically polarized wave independently is required.
[0014]
On the other hand, when an array antenna is configured for a mobile communication base station, it is generally arranged so that the element spacing is one wavelength or less at the upper limit of the used frequency. This is because a grating lobe occurs when the element spacing is longer than one wavelength, and the gain of the array antenna is reduced. On the other hand, in order to obtain a large directivity gain and prevent a decrease in antenna efficiency due to mutual coupling between elements, the element spacing is made as large as possible within this range. Here, when the array antenna is configured using a printed circuit board, the elements are reduced in size due to the dielectric constant, so that the apparent element spacing is further increased. For example, the vertically polarized array antennas arranged at intervals s and the horizontally polarized array antennas arranged at intervals s are shifted on the same substrate by s / 2, and each array is configured on the back side of the ground plane. Connect to the directivity shaping power supply circuit. The array feeding circuit is provided independently for each of the vertically polarized wave and the horizontally polarized wave. As a result, the beam width can be controlled independently for each polarization. For example, the distance between the vertically polarized patch elements 1 and 2 and the distance between the horizontally polarized patch elements 3 and 4 may be adjusted as appropriate so that the horizontal plane beam widths of both polarized waves coincide with each other. In addition, this structure has an advantage that large polarization isolation can be secured because the horizontally polarized antenna and the vertically polarized antenna are spatially separated.
[0015]
Needless to say, the structure of the transmitting antenna and the receiving antenna may be other than the patch antenna as long as it has sensitivity to two orthogonal polarizations. Of course, the polarization need not be a combination of vertical and horizontal polarization. Furthermore, when the array antenna for vertical polarization and the array antenna for horizontal polarization are arranged one-dimensionally on the same plane, if the elements do not come into physical contact, they are shifted by s / 2 or less or s / 2 or more. You can also
Example 2
FIG. 2 is a configuration diagram of an antenna apparatus according to a second embodiment of the present invention. Here, the embodiment of the present invention will be described based on a polarization-sharing array antenna apparatus using vertical polarization and horizontal polarization.
[0016]
In FIG. 2, 11 and 12 are vertical polarization patch elements, 13 and 14 are horizontal polarization patch elements, 15 is a microstrip line as a feed line for the horizontal polarization patch element 13, and 16 is horizontal polarization. A microstrip line that is a feed line for the wave patch element 14, 17 is a microstrip line that is a feed line for the vertically polarized patch element 11, and 18 is a feed line for the vertically polarized patch element 12. The microstrip lines 19 and 20 are dielectric substrates.
[0017]
In the second embodiment, an array antenna composed of a vertically polarized patch element 11 and a horizontally polarized patch element 13 and an array antenna composed of a vertically polarized patch element 12 and a horizontally polarized patch element 14 are used. Since these are configured on different printed circuit boards, by adjusting the installation interval between the two printed circuit boards, it is possible to reduce the influence of electromagnetic field diffraction at the end of the ground plane and to arbitrarily control the beam width. The same effect can be obtained by forming all antenna circuits on a single printed board and adjusting the circuit pattern interval.
Example 3
FIG. 3 is a block diagram of an antenna apparatus according to a third embodiment of the present invention. Here, an embodiment of the present invention will be described based on a polarization sharing array antenna apparatus using vertical polarization and horizontal polarization.
[0018]
In FIG. 3, 11 and 12 are vertical polarization patch elements, 13 and 14 are horizontal polarization patch elements, 15 is a microstrip line as a feed line for the horizontal polarization patch element 13, and 16 is horizontal polarization. A microstrip line that is a feed line for the wave patch element 14, 17 is a microstrip line that is a feed line for the vertically polarized patch element 11, and 18 is a feed line for the vertically polarized patch element 12. Are microstrip lines, 19 and 20 are dielectric substrates, and 21 is a reflector.
[0019]
In the third embodiment, an array antenna composed of a vertically polarized patch element 11 and a horizontally polarized patch element 13 and an array antenna composed of a vertically polarized patch element 12 and a horizontally polarized patch element 14 are used. Since these are configured on different printed circuit boards, it is possible to reduce the influence of the electromagnetic field diffraction at the end of the base plate and the end of the reflecting plate by adjusting the installation interval between the two printed circuit boards. Further, the backward radiation can be suppressed by the reflection plate behind the printed circuit board.
Example 4
FIG. 4 is a configuration diagram of an antenna apparatus according to a fourth embodiment of the present invention. Here, a description will be given based on a dual-polarized antenna device using vertical polarization and horizontal polarization.
[0020]
4, (a) is a top view, (b) is a cross-sectional view, 61 is a horizontally polarized radiation element, 62 is a vertically polarized radiation element, 63 is a vertical polarization excitation probe, and 64 is horizontal. Polarization excitation microstrip line, 65 is a vertical polarization excitation microstrip line, 66 is a ground plane having a conductive layer such as copper foil, 67 is a reflector, and 68 is for exciting a horizontally polarized radiation element 61 A slot 69 formed in the ground plane 66 indicates a dielectric substrate on which circuits such as microstrip lines 64 and 65 are disposed. The dielectric substrate 69 is attached in contact with the back surface of the ground plane 66. The horizontally polarized radiation element 61 is excited from the back by a slot 68 coupled to a microstrip line 64 on a dielectric substrate 69. The vertically polarized radiation element 62 is excited by a vertically polarized wave excitation probe 63 that passes through the ground plane 66 and is coupled to the microstrip line 65 on the dielectric substrate 69.
[0021]
Next, the principle of this antenna will be described. In general, when an antenna is configured using a dielectric material such as a printed circuit board, the antenna can be physically downsized, but there is a problem that the input characteristics are narrowed. For example, a patch antenna, which is a typical printed antenna, has a very narrow band because the distance between the radiating element and the ground plane is narrow. Therefore, if the ground plane is narrower than the element to lower the antenna Q and a reflector is installed behind the antenna, a wide band antenna with less back radiation can be realized. In this example, a radiating patch and a feeding circuit coupled in a DC manner by a probe are used for vertical polarization, and a radiating patch and a power coupling circuit electromagnetically coupled through a slot are used for horizontal polarization. Thereby, it is possible to realize a wide band antenna with a simple structure.
Example 5
FIG. 5 is a configuration diagram of an antenna apparatus according to a fifth embodiment of the present invention. The shape of the ground plane is different from that of the above-described fourth embodiment.
[0022]
In FIG. 5, 71 is a horizontally polarized radiation element, 72 is a matching ground plate protrusion, 73 is a vertically polarized radiation element, 74 is a vertical polarization excitation probe, 75 is a horizontal polarization excitation microstrip line, 76 Is a microstrip line for vertical polarization excitation, 77 is a ground plane, 78 is a reflection plate, 78a is a dielectric substrate on which a circuit such as a microstrip line is arranged, and 79 is for exciting a radiation element 71 for horizontal polarization It is a slot formed in the main plate 77.
[0023]
In general, when a slot antenna is used in an environment where radiation in one direction is required, a reflector is installed behind the slot antenna, but there is a problem that the input characteristics are narrowed due to the influence of the reflector. In addition, when the slot antenna is excited using a low impedance line such as a microstrip line, matching with the antenna can be obtained by an offset feeding method in which a microstrip line is arranged near the slot end. There is a problem that the symmetry of directivity in the plane is broken. Therefore, by deforming only the ground plane on the side surface of the slot like the matching ground plane projection 72, matching with the microstrip line is possible even when symmetrical power feeding is adopted at the center of the slot. Note that the shape of the ground plane projection 72 is not necessarily rectangular.
[0024]
FIG. 6 shows a modified example in which the ground plane projections of FIG. 5 are formed in a T shape and are arranged horizontally. In FIG. 6, 81 is a horizontally polarized radiation element, 82 is a ground plane, 82a is a slot formed on the ground plane 82, 83 is a T-shaped ground plane protrusion, 84 is a vertically polarized radiation element, and 85 is for vertically polarized waves. A feed probe for exciting the radiating element 84, 86 is a microstrip line for vertical polarization excitation, and 87 is a microstrip line for horizontal polarization excitation. Note that two antennas having the same shape as the antenna are arranged in the same plane. 88 is a feed line for coupling these two antenna arrangements for vertically polarized radiating elements and feeding them simultaneously. 89 is a feed line for joining the two antenna arrangements for horizontally polarized waves and feeding simultaneously. A line, 90 is a reflector, and 90a is a dielectric substrate on which a microstrip line and a circuit are arranged.
[0025]
FIG. 7 is an actual measurement graph of the return loss characteristics and the degree of coupling between the polarizations of the dual-polarized antenna shown in FIG. The degree of coupling between the polarizations is −35 dB or less, and it can be seen that each element antenna operates independently. Since this is smaller than the degree of coupling between the polarizations of the conventional antenna shown in FIG. 10, it is extremely advantageous in practice.
[0026]
FIG. 8 is a measurement example graph of the directivity in the horizontal plane of the above-described dual-polarized antenna, and the horizontal beam width is 45 degrees with respect to the slot interval of 0.58λ. Needless to say, this value varies depending on the horizontal arrangement interval.
[0027]
In addition, by adjusting the horizontal widths of the radiating element 71 and the radiating element 73 in FIG. 5, the beam width can be controlled independently with respect to the horizontal polarization and the vertical polarization. Needless to say, the radiating element 71 and the radiating element 73 can be configured by printing on a printed circuit board. The same applies to the examples of FIGS.
Example 6
FIG. 9 is a configuration diagram of an antenna apparatus according to a sixth embodiment of the present invention. The point from which the ground-plate protrusion is asymmetrically installed only on one side is different from Example 5.
[0028]
In FIG. 9, 91 is a horizontally polarized radiation element, 92 is a ground plane, 92a is a slot formed in the ground plane 92, 93 is a T-shaped ground plane protrusion, 94 is a vertically polarized radiation element, and 95 is for vertically polarized waves. A feeding probe for exciting the radiating element 94, 96 a microstrip line for vertical polarization excitation, and 97 a microstrip line for horizontal polarization excitation. Note that two antennas having the same shape as the antenna are arranged in the same plane. 98 is a feed line for coupling these two antenna arrangements for vertically polarized radiating elements and feeding them simultaneously. 99 is a feed line for joining the two antenna arrangements for horizontally polarized waves and feeding them simultaneously. A line, 100 is a reflector, and 101 is a dielectric substrate on which a microstrip line and a circuit are arranged.
[0029]
In this example, since there is no T-shaped projection between two arranged ground planes, the element arrangement in the horizontal plane can be made closer than the antenna of the fifth embodiment, and there is an advantage that the range of beam width control is increased. is there.
[0030]
【The invention's effect】
According to the present invention, it is possible to easily change and adjust the horizontal beam widths of two orthogonally polarized beams with a relatively simple structure and low cost, which is useful for mobile communication of the polarization diversity system. A beam width control method for a wave sharing antenna can be provided.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a dual-polarized antenna according to a first embodiment of the present invention.
FIG. 2 is a configuration diagram of a dual-polarized antenna according to a second embodiment of the present invention.
FIG. 3 is a configuration diagram of a dual-polarized antenna according to a third embodiment of the present invention.
FIG. 4 is a configuration diagram of a dual-polarized antenna according to a fourth embodiment of the present invention.
FIG. 5 is a configuration diagram of a dual-polarized antenna according to a fifth embodiment of the present invention.
FIG. 6 is a modified configuration diagram of a fifth embodiment in which a ground plate protrusion is formed in a T shape.
FIG. 7 is a graph showing an actual measurement example of the return loss characteristic and the degree of coupling between polarizations of the dual-polarized antenna according to the fifth embodiment of the present invention.
FIG. 8 is a measurement example graph of the directivity in the horizontal plane of the dual-polarized antenna according to the fifth embodiment of the present invention.
FIG. 9 is a configuration diagram of a dual-polarized antenna according to a sixth embodiment of the present invention.
10 is a configuration diagram of a conventional antenna shown in Reference Document 1. FIG.
11 is a configuration diagram of a conventional antenna shown in Reference Document 2. FIG.
12 is a configuration diagram of a conventional antenna shown in Reference 3. FIG.
[Explanation of symbols]
1, 2: Patch element 3 for vertical polarization 3, 4: Patch element for horizontal polarization 5: Microstrip line as feed line for patch element 3 for horizontal polarization 6: Patch element 4 for horizontal polarization 7: Microstrip line as a feed line for the vertically polarized patch element 8 8: Microstrip line as a feed line for the vertically polarized patch element 2 9: Dielectric substrate

Claims (2)

The first and second antennas that can excite the polarization plane A and the third antenna and the fourth antenna that can excite the polarization plane B different from the polarization plane A are alternately adjacent to each other. In this way, two sets of the dual- polarized antenna array , which are arranged in a row as a whole, are arranged in parallel so that antennas of the same polarization plane are adjacent to each other on the same plane on different ground planes. A method of controlling the beam width of the arranged polarization sharing antenna,
A dual-polarized antenna characterized by controlling the beam width in the direction orthogonal to the column direction of the dual-polarized antenna array by adjusting the interval between the two sets of dual-polarized antenna arrays on the separate ground planes Beam width control method.   The feed line of each of the first antenna and the second antenna is connected to the first coupling point, and the feed line of each of the third antenna and the fourth antenna is connected to the second coupling point. The first coupling point is connected to a first feeding unit for exciting the polarization plane A, and the second coupling point is connected to a second feeding unit for exciting the polarization plane B. A beam width control method for a dual-polarized antenna.

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