JP3837553B2 - Patch antenna - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an antenna, in particular, the feed lines, the ground plane and the patch relates to a patch antenna comprising stacked sandwiching an insulator between each of the (radiating elements) and in this order.
[0002]
[Prior art]
The patch antenna as described above is biased to realize high-quality and high-speed communication such as a small mobile communication terminal represented by a mobile phone, an analog or digital wireless image transmission system, a wireless LAN, and a home appliance network. Used in areas where wave diversity technology is required.
[0003]
Radio waves propagate through space due to the interaction between orthogonal electric and magnetic fields. At this time, the plane where the electric field is generated is called the polarization plane. In principle, it is necessary to match this polarization when transmitting and receiving radio waves. As long as direct waves are used for transmission / reception of radio waves, there is almost no deviation in polarization, but it is known that the polarization plane changes when there is reflection or diffraction.
[0004]
In recent years, there has been an increasing demand for wirelessly transmitting data, but fading due to multi-wave propagation occurs especially in urban areas where there is a lot of diffraction and reflection of radio waves, which requires high communication quality. It is known to greatly affect data transmission.
[0005]
In such a case, a polarization diversity technique that selectively uses a polarized antenna that can perform better communication between two different polarized waves is used. The polarizations to be switched are switching between vertical and horizontal polarizations of linear polarization and switching between right and left polarizations of circular polarization.
[0006]
[Problems to be solved by the invention]
An object of the present invention is to realize the polarization diversity technique with one small patch antenna that can be used in, for example, a portable terminal.
[0007]
[Means for Solving the Problems]
The patch antenna according to the present invention further includes a diode, the anode of the diode is connected to one end of the feeding path, the cathode of the diode is grounded, and the ground planes are arranged in directions substantially orthogonal to each other. Two slots provided so that the center overlaps the feed line, and the length of the feed line from the one end of the feed line to the center of one of the two slots is about the effective wavelength. The length of the feed line from the one end of the feed line to the center of the other of the two slots is about 1/4 of the effective wavelength. In this way, polarization switching can be performed by selecting a slot that feeds the patch depending on whether or not a DC bias voltage is applied to the diode via the feed line.
[0008]
Another embodiment of the patch antenna according to the present invention is characterized in that the patch is rectangular and the two slots are parallel to two sides of the patch. In this way, it is possible to realize a patch antenna that can switch between vertical polarization and horizontal polarization with a simple configuration.
[0009]
Still another embodiment of the patch antenna according to the present invention is the patch antenna, wherein the distribution line is straight. If it does in this way, the shape of a distribution line way can be made the simplest.
[0010]
Still another embodiment of the patch antenna according to the present invention is characterized in that the distribution line is L-shaped so as to bend at a substantially right angle between the two slots. In this way, the degree of freedom when selecting the position of the slot with respect to the patch can be increased.
[0011]
Still another embodiment of the patch antenna according to the present invention is such that the patch has a shape obtained by cutting off a pair of diagonals of a square patch, and the cut-off area is selected so that circular polarization is generated. It is characterized by. This makes it possible to switch between circularly polarized right-handed polarization and left-handed polarization.
[0012]
Still another embodiment of the patch antenna according to the present invention is characterized in that the patch is a circular patch configured to generate circular polarization by a degenerate separation method. This makes it possible to switch between circularly polarized right-handed polarization and left-handed polarization.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a top view and a side view showing a structure of an embodiment of a patch antenna according to the present invention. The patch antenna 1 includes a linear feed flat feed line 2 for power feeding represented by a microstrip line, a ground plane 4, and a rectangular patch 6 having one side dimension W, and insulators 14 and 16 interposed therebetween. It is prepared by laminating it. The patch antenna 1 further includes a diode 8 connected to one end a of the flat electric wire 2. The ground plane 4 is provided with two slots 10 and 12 parallel to the two sides of the patch 6, and the centers b and c of each of these slots are on the feeder line 2, and from the center b of the slot 10. The length L ₁ of the flat electric wire 2 to the end a of the flat electric wire 2 is about ½ of the effective wavelength, and the flat type from the center c of the slot 12 to the end a of the flat electric wire 2. the length _{L 2} of the electrical lines 2 is about 1/4 of the effective wavelength.
[0015]
FIG. 2 is a top view and a side view showing the structure of another embodiment of the patch antenna according to the present invention. The patch antenna 21 includes an L-shaped planar feed line 22 for feeding that is bent substantially at a right angle, a ground plane 24, a rectangular patch 26 having a side dimension W, and insulators 34 and 36 therebetween. Prepared by sandwiching. The patch antenna 21 further includes a diode 28 connected to one end a ′ of the planar electric wire path 22. The ground plane 24 is provided with two slots 30 and 32 which are respectively parallel to the two sides of the patch 26, and the centers b ′ and c ′ of these slots are on the planar feed line 22. The length L ₃ of the planar wire 22 from the center b ′ to the end a ′ of the planar wire 22 is about ½ of the effective wavelength, and the planar wire 22 from the center c ′ of the slot 32. the length L ₄ of the planar electric line 22 to the end a'is about 1/4 of the effective wavelength. In this embodiment, the distance between the slots 10 and 12 is limited to ¼ of the effective wavelength in the embodiment of FIG. This has the advantage that the degree of freedom in selecting the positions of the slots 30 and 32 in the patch 26 can be increased.
[0016]
FIG. 3 is a diagram for explaining the principle of polarization switching in the patch antenna of FIG. The slots 10 and 12 used for feeding the patch 6 are located at the center of the slot 12 on a point b where the center of the slot 10 is separated from the tip a of the feeding line 2 by a distance corresponding to one half of the effective wavelength. Is arranged on the feed line 2 so as to be on a point c away from the tip a by a distance corresponding to a quarter of the effective wavelength. On the other hand, as shown in FIG. 3A, when a DC bias voltage corresponding to the forward direction of the diode 8 is applied to the feed line 2 simultaneously with the transmission signal, the diode 8 at the tip of the feed line 2 is conducted and short-circuited. As a result, the current is maximized at a point b that is ½ of the effective wavelength from the tip of the feed line 2 as schematically shown, and magnetic field coupling is generated by the slot 10 centered on this point b. Patch 6 is powered by slot 10. At this time, the current is minimized on a point c that is ½ of the effective wavelength from the tip a of the feed line 2, so that magnetic field coupling does not occur depending on the slot 12 that is centered on the point c. Power supply to the patch 6 is not performed. On the other hand, as shown in FIG. 3B, if the DC bias voltage is not applied to the feed line 2, the tip a of the feed line 2 is opened. The current is maximized at a point c that is a quarter of the distance, and magnetic coupling is caused by the slot 12 centered on the point c, and the patch 6 is fed by the slot 12. At this time, the current is minimized on a point b that is ½ of the effective wavelength from the tip a of the feed line 2, so that magnetic field coupling does not occur depending on the slot 10 that is centered on the point b. Power supply to the patch 6 is not performed. In this way, the two slots 10 and 12 used for power feeding to the patch 6 can be switched by the DC bias voltage applied to one diode 8. Since these two slots 10 and 12 are arranged in directions almost orthogonal to each other, the horizontal polarization and the vertical polarization can be switched by switching the slot that feeds the patch 6. Also in the case of the embodiment as shown in FIG. 2, the horizontal polarization and the vertical polarization can be switched by the same principle.
[0017]
FIG. 4 is a graph showing experimental results obtained by measuring the radiation directivity of the patch antenna according to the present invention. FIG. 4A shows a radiation pattern when a DC bias voltage is not applied to the feed line and the tip of the feed line is open. FIG. 4B is a radiation pattern when a DC bias voltage is applied to the feed line and the tip of the feed line is short-circuited. Each vertical axis represents relative output in decibels, and the horizontal axis represents azimuth in degrees. In these graphs, the straight line represents vertical polarization and the dotted line represents horizontal polarization. As can be seen from these graphs, vertical polarization and horizontal polarization can be switched depending on whether or not a DC bias voltage is applied to the feed line.
[0018]
FIG. 5 is a top view and a side view showing the configuration of still another embodiment of the patch antenna according to the present invention. The patch antenna 41 has a linear feed planar feed line 42 typified by a microstrip line and the like, a ground plane 44, and a pair of diagonal parts 57 and 58 having a side dimension of W. The patch 46 is shaped and laminated with insulators 54 and 56 sandwiched therebetween. The areas of the patch cut-out portions 57 and 58 are determined so that circularly polarized waves are generated by the degenerate separation method. The patch antenna 41 further includes a diode 48 connected to one end d of the planar electric wire 42. The ground plane 44 is provided with two slots 50 and 52 parallel to the two sides of the patch 46, and the centers e and f of these slots are on the feeder line 42, and from the center e of the slot 50. The length L ₅ of the flat electric wire 42 to the end d of the flat electric wire 42 is about ½ of the effective wavelength, and the flat type from the center f of the slot 52 to the end e of the flat electric wire 42 is used. the length _{L 6} of the wire path 42 is about 1/4 of the effective wavelength. Which of the slots 50 and 52 is used for feeding the planar wire 42 is selected according to whether or not a DC bias voltage is applied to the diode 48 via the planar wire 42 as in the embodiment of FIG. can do. In the present embodiment, the right-handed polarized wave and the left-handed polarized wave can be switched by switching the slot that feeds power to the planar electric wire path 42 in this way.
[0019]
FIG. 6 is a top view and a side view showing the configuration of still another embodiment of the patch antenna according to the present invention. The patch antenna 61 is on a circumference such that a straight feeding plane type feeding line 62 represented by a microstrip line or the like, a ground plane 64, and a straight line connecting each other with a radius R are the center of the circle. A circular patch 66 having two indentations 77 and 78 in position is provided, laminated with insulators 74 and 76 therebetween. The areas of the depressions 77 and 78 are determined so that circularly polarized waves are generated by the degenerate separation method. The patch antenna 61 further includes a diode 68 connected to one end d ′ of the planar electric wire 62. The ground plane 64 is provided with two slots 70 and 72 parallel to the other two sides of a right-angled isosceles triangle in which a straight line perpendicular to the straight line connecting the two depressions 77 and 78 does not form a right angle. The centers e ′ and f ′ of each of these slots are on the feeder line 62, and the length L of the flat wire path 62 from the center e ′ of the slot 70 to the end d ′ of the flat wire path 62 is ₇ is about ½ of the effective wavelength, and the length L ₈ of the planar wire 62 from the center f ′ of the slot 72 to the end d ′ of the planar wire 62 is about ¼ of the effective wavelength. It is. Which of the slots 70 and 72 is used to feed the planar wire 62 is selected according to whether or not a DC bias voltage is applied to the diode 72 via the planar wire 62 as in the embodiment of FIG. can do. In the present embodiment, the right-handed polarized wave and the left-handed polarized wave can be switched by switching the slot that feeds power to the planar electric wire path 62 in this way.
[0021]
【The invention's effect】
According to the present invention, a patch having the same structure as the conventional one can be used by using a well-known design method, so that there is little influence on the radiation characteristic, and only one diode is used. Thus, a small patch antenna capable of switching the polarization can be realized.
[Brief description of the drawings]
FIG. 1A is a top view showing a configuration of an embodiment of a patch antenna according to the present invention, and B is a side view thereof.
FIG. 2A is a top view showing a configuration of another embodiment of the patch antenna according to the present invention, and B is a side view thereof.
FIGS. 3A and 3B are diagrams illustrating the principle of polarization switching in the patch antenna of FIG. 1;
FIG. 4 is a graph showing experimental results of measuring radiation directivity of the patch antenna according to the present invention.
5A is a top view showing a configuration of still another embodiment of the patch antenna according to the present invention, and B is a side view thereof. FIG.
6A is a top view showing a configuration of still another embodiment of the patch antenna according to the present invention, and B is a side view thereof. FIG.
[Explanation of symbols]
1, 21, 41, 61 Patch antenna 2, 22, 42, 62 Planar feed line 4, 24, 44, 64 Ground plane 6, 26, 46, 66 Patch 8, 28, 48, 68 Diode 10, 12, 30, 32, 50, 52, 70, 72 slots 14, 16, 34, 36, 54, 56, 74 , 76 insulators

Claims (6)

  A patch antenna comprising a feeder line, a ground plane, and a patch laminated in this order with an insulator interposed therebetween, further comprising a diode, and connecting the anode of the diode to one end of the feeder path The diode has a cathode grounded, and the ground plane has two slots that are arranged in directions substantially orthogonal to each other and that each center is overlapped with the feed line, and the one of the feed lines The length of the feed line from the end to the center of one of the two slots is about ½ of the effective wavelength, and from the one end of the feed line to the other center of the two slots A patch antenna characterized in that the length of the feeder line is about 1/4 of the effective wavelength.   2. The patch antenna according to claim 1, wherein the patch is a square, and the two slots are parallel to two sides of the patch.   The patch antenna according to claim 1 or 2, wherein the distribution line is straight.   3. The patch antenna according to claim 1, wherein the distribution line is an L-shape that bends at a substantially right angle between the two slots. 4.   2. The patch antenna according to claim 1, wherein the patch has a shape in which a pair of diagonals of a square patch is cut off, and a cut-off area is selected so that circular polarization occurs. Patch antenna to be used.   2. The patch antenna according to claim 1, wherein the patch is a circle provided with two depressions on a circumference, and a straight line connecting the two depressions passes through the center of the patch, and the 2 on the patch surface. A patch antenna characterized in that the area of two depressions is selected so that circular polarization occurs.

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