JP2005295188A - Multi-beam antenna - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the size and the thickness of a multi-beam antenna which can switch directivity in a plurality of directions and further which can obtain a high F/B ratio. <P>SOLUTION: The multi-beam antenna includes a non-power supply patch antenna element 1 of one element, monopole antenna elements 3A-3C of N elements (N: natural number) arranged on a circumference in which the non-power supply patch antenna element 1 is at a center, and a switching means for selectively switching a power supply and a terminal end to the monopole antenna elements 3A-3C. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention is equipped with an information communication function, a storage function, and the like, and has directivity in a plurality of directions suitable for use in a micro communication module that is used by being mounted on various electronic devices such as a personal computer, a mobile phone, or an audio device. The present invention relates to a multi-beam antenna that can be switched.

  For example, information such as music, voice or various data and images can be easily handled by a personal computer, a mobile device or the like with the recent digitization of data. In addition, such information is subjected to band compression by voice codec technology or image codec technology, and an environment is being prepared in which digital communication and digital broadcasting are easily and efficiently distributed to various communication terminal devices. For example, audio / video data (AV data) can also be received by a mobile phone.

  On the other hand, transmission / reception systems for data and the like are used in various places such as homes by proposing a simple wireless network system that can be applied even in a small area. As a wireless network system, for example, a short-range wireless communication called Bluetooth, a narrow band wireless communication system of 5 GHz band proposed by IEEE802.1a, a wireless LAN system of 2.45 GHz band proposed by IEEE802.1b, or Bluetooth. A next-generation wireless communication system such as a system is drawing attention.

  By the way, when an antenna having no directivity in the characteristic direction is used, there is a problem that communication quality deteriorates due to an interference wave generated by reflection on a building wall or the like in a multi-wave propagation environment where many radio waves exist. .

  Therefore, an antenna that directs directivity in a specific direction has attracted attention.

  As a directional antenna, there is a Yagi-Uda antenna used for television reception. In Yagi-Uda antenna 100, as shown in FIG. 21, in addition to radiator 111 that radiates radio waves, reflector 112 that is slightly longer than radiator 111 and waveguide 113 that is shorter than radiator 111 are arranged in the front and rear. By doing so, directivity as shown in FIG. 22 is exhibited.

  There has been proposed a method of directing directivity in a characteristic direction (directivity control antenna) by switching a plurality of these Yagi antennas side by side (for example, see Patent Document 1 and Patent Document 2).

JP-A-11-27038 JP 2003-142919 A

  However, since the antenna device disclosed in Patent Document 1 has a structure in which a plurality of Yagi antennas are arranged, a reflector and a plurality of directors are required, and thus there is a problem that the antenna device cannot be reduced in size. Furthermore, in this antenna device, the monopole antenna protrudes from the ground plate in the direction perpendicular to the substrate. There was a problem that the thickness could not be reduced. Also, when the structure of this antenna device is formed on a printed board that is changed from a monopole antenna to a dipole antenna, there is a problem that it is difficult to mount a changeover switch or the like because it is difficult to arrange the ground plate in the vicinity. .

  In the multi-beam antenna disclosed in Patent Document 2, the space between the director and the reflector is shared, and the multi-beam is formed by switching the feeding position. Since it is used, a plurality of waveguides are necessary, there is a limit to sharing, and miniaturization is difficult.

  Therefore, the present invention has been devised in view of the above-described problems, and its object is to switch the directivity in a plurality of directions and to reduce the size and thickness of the multi-beam antenna. Another object is to obtain a high F / B ratio (antenna beam longitudinal ratio).

  Other objects of the present invention and specific advantages obtained by the present invention will become more apparent from the description of embodiments described below.

  A multi-beam antenna according to the present invention includes one parasitic patch antenna element, N element (N: natural number) monopole antenna elements arranged on a circumference around the parasitic patch antenna element, It is characterized by comprising switching means for selectively switching between feeding and termination of the N element (N: natural number) monopole antenna element.

  In this multi-beam antenna, the monopole antenna element can be a capacitively loaded monopole antenna element. Moreover, the monopole antenna element which consists of said capacity | capacitance loading monopole antenna element can be equipped with the shorting pin for a matching.

  In the present invention, since the parasitic patch antenna element provided in the center is shared as a reflector, a plurality of reflectors are not required, and thus the multi-beam antenna can be reduced in size.

  Further, by adopting a capacitively loaded monopole antenna element as an N element (N: natural number) monopole antenna element arranged on the circumference centering on the parasitic patch antenna element, the thickness can be further reduced. Can be planned.

  A capacitively loaded monopole antenna element that selectively feeds a capacitively loaded monopole antenna element, which is a radiating element, and 50. By terminating Ω, the F / B ratio can be improved.

  Furthermore, a high F / B ratio can be realized by optimizing the distance between the center parasitic patch antenna element and the capacitively loaded monopole antenna element and the distance between the feeding pin and the shorting pin of the capacitively loaded monopole antenna element. it can.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  The multi-beam antenna according to the present invention is configured as shown in FIG.

  The multi-beam antenna 10 shown in FIG. 1 constitutes a multi-beam antenna in three directions. As shown in FIG. One parasitic patch antenna element 1 constituted by a pattern formed on the dielectric substrate 11 and a three-element capacitively loaded monopole arranged on the circumference around the parasitic patch antenna element 1 Antenna elements 2A, 2B, and 2C are provided.

  In this multi-beam antenna 10, square capacitively loaded monopole antenna elements 2A, 2B, and 2C that operate as radiating elements are arranged every 120 ° around a regular hexagonal parasitic patch antenna element 1 that operates as a reflector. Yes.

  Here, the capacity-loaded monopole antenna element 2 has a monolithic structure in which a feed pin 22 having a length L of ¼ wavelength (λ / 4) is erected on a ground plate 21 as shown in FIG. With respect to the pole antenna element 20, as shown in FIG. 3 (B), the length of the power feed pin 22 is shortened by loading the capacity by providing a capacity electrode 23 at the tip of the power feed pin 22. The matching can be adjusted by the short-circuit pin 24. λ is the resonance wavelength.

  In the multi-beam antenna 10 in this embodiment, the entire conductor 21 that covers the back surface of the dielectric substrate 11 is used as a ground plate, and the capacitance of the monopole antenna elements 2A, 2B, and 2C with three elements is formed on the front surface of the dielectric substrate 11. The patterns of the electrodes 23A, 23B, and 23C are formed, and the rear ends of the power supply pins 22A, 22B, and 22C that penetrate the dielectric substrate 11 and have tips connected to the capacitor electrodes 23A, 23B, and 23C are the power supply points. Port1, Port2, and Port3. Further, short-circuit pins 24A, 24B, and 24C are provided through the dielectric substrate 11 to short-circuit the capacitive electrodes 23A, 23B, and 23C to the entire surface conductor 21, that is, the ground plate.

  The multi-beam antenna 10 can selectively switch between feeding and termination for the three-element monopole antenna elements 2A, 2B, and 2C by the feeding circuit 5 having the configuration shown in FIG. Yes.

  The feeder circuit 5 includes three changeover switches WS1, WS2, WS3 each having two contacts per circuit, each movable terminal being connected to the feed points Port1, Port2, Port3 of the capacitively loaded monopole antenna elements 2A, 2B, 2C. A single-circuit three-contact changeover switch WS4 having a movable terminal connected to the power supply unit 50, and feedpoints Port1, Port2, and Port3 of the capacity-loaded monopole antenna elements 2A, 2B, and 2C. Three terminal resistors R1, R2, and R3 each terminated at 50Ω through WS3, and feeding the capacitively loaded monopole antenna elements 2A, 2B, and 2C through the changeover switches WS1, WS2, WS3, and WS4 It is possible to selectively switch power supply and termination for the points Port1, Port2, and Port3. It has become to so that.

  When the multi-beam antenna 10 configured as described above is fed to any one of the capacity-loaded monopole antenna elements 2A, 2B, and 2C, and the termination conditions of the remaining two radiating elements are changed, FIG. It exhibits the input characteristics as shown.

Here, FIG. 5 shows a case where power is supplied to Port 1 and Port 2 and Port 3 have the following three termination conditions a, b, and c.
Termination condition a: When Port 2 and Port 3 are terminated by 50Ω Termination condition b: When Port 2 and Port 3 are opened Termination condition c: When Port 2 and Port 3 are short-circuited Analyzing input characteristics using an electromagnetic field simulator (CST Microwave Studio) Shows the results. The diameters of the power supply pins 22A, 22B, and 22C and the short-circuit pins 24A, 24B, and 24C of the capacitively loaded monopole antenna elements 2A, 2B, and 2C are 1.0 mm, and the multi-beam antenna 10 has a relative dielectric constant of 2.6. The printed circuit board is printed on a dielectric substrate 11 made of a Teflon substrate having a thickness of 1.6 mm.

  As shown in FIG. 5, the multi-beam antenna 10 has two resonance characteristics. Henceforth, let this low resonant frequency be f1, and let a high resonant frequency be f2.

  The zx plane radiation directivity at each resonance frequency f1, f2 is shown in FIGS. 6 and 7, and the xy plane radiation directivity is shown in FIGS. At the resonance frequency f1, there is no significant change in each condition. On the other hand, at the resonance frequency f2, the F / B ratio in the termination condition b and the termination condition c is about 10 dB, whereas in the termination condition a, it is 20.1 dB. That is, high directivity can be obtained by terminating Port 2 and Port 3 by 50Ω.

  Here, the operation principle of the multi-beam antenna 10 will be described.

  The current distribution at the resonance frequencies f1 and f2 of the termination condition a of the multi-beam antenna 10 is shown in FIGS.

  As shown in FIG. 10, at the resonance frequency f1, the currents flowing through the patch A, that is, the patch A of the capacitively loaded monopole antenna element 2A, and the patches 2, 3 of the capacitively loaded monopole antenna elements 2B and 2C, are reversed. In the regular hexagonal patch D of the central parasitic patch antenna element 1, the current from Port 1 to Port 2 and 3 is strongly distributed. Therefore, the directivity of the patch antenna is shown, and it is slightly tilted due to the difference in the number of elements. When using at this resonance frequency, a plurality of waveguides are required. Further, as shown in FIG. 11, at the resonance frequency f2, the current of the patch A of the capacitively loaded monopole antenna element 2A and the currents of the ports 2, 3 patches B and C are in phase, and the positive six of the parasitic parasitic patch antenna element 1 is obtained. The square patch D has almost no current distribution. The current flowing through the patch A of the Port 1 is more strongly distributed than the Ports 2 and 3, that is, the patches B and C of the capacitively loaded monopole antenna elements 2B and 2C. As described above, at a high frequency, a three-element capacitively loaded monopole array is formed, and the directivity is tilted toward the Port 1 where the current is strongly distributed, that is, the patch A side of the capacitively loaded monopole antenna element 2A.

  As described above, in the multi-beam antenna 10, when any one of the capacitively loaded monopole antenna elements 2A, 2B, and 2C is excited, the other two elements are 50Ω terminated so that they are higher on the excitation element side. The directivity tilts at the F / B ratio. The directivity can be switched in three directions by selecting the excitation element, and the directivity is switched by switching the feeding to the capacitively loaded monopole antenna elements 2A, 2B, and 2C and the 50Ω termination by the feeding circuit 50. be able to.

  Here, in the multi-beam antenna 10, the structural parameters shown in FIG. 12, that is, the size ps of the entire conductor 21 covering the back surface of the ground plate, that is, the dielectric substrate 11, the regular hexagonal patch of the parasitic parasitic patch antenna element 1 at the center. D, the length of one side hs, the distance d between the parasitic patch antenna element 1 and the radiating element, that is, the capacitively loaded monopole antenna elements 2A, 2B, 2C, the feeding pins 22A, 22B, 22C of the radiating element and the shorting pins 24A, 24B, The interval rd of 24C greatly affects the antenna characteristics. Therefore, parameters for the F / B ratio (radiation gain front-to-back ratio) and the horizontal half-value width in the multi-beam antenna 10 used as the directivity switching antenna are examined.

  The length of one side of the patches A, B, C of the capacitively loaded monopole antenna elements 2A, 2B, 2C is fixed at rs = 10.8 mm, and the size of the entire conductor 21 covering the ground plate, that is, the back surface of the dielectric substrate 11 As shown in FIG. 13, the F / B ratio and the horizontal plane directivity when ps is changed are reduced as the size of the ground plate is reduced.

  FIG. 14 shows the F / B ratio and horizontal plane directivity when ps = 48 mm and the size hs of the central element is changed. The F / B ratio is most improved when hs = 9 mm.

  FIG. 15 shows the F / B ratio and horizontal plane directivity when the distance d between the central element and the radiating element is changed. From this result, the F / B ratio becomes maximum when d = 1.1 mm.

  Further, FIG. 16 shows the F / B ratio and the horizontal half-width when the distance rd between the power supply pins 22A, 22B, and 22C and the short-circuit pins 24A, 24B, and 24C of the radiating element is changed. Parameters with high F / B ratio are d = 1.1 mm, rd = 2.0 mm, and d = 0.8 mm, rd = 2.5 mm.

  The results are summarized in Table 1.

  Here, in this multi-beam antenna 10, the guide wavelength λg is given by λ√ε. Therefore, when the dielectric constant ε is taken into consideration, the antenna size can be reduced by using the dielectric substrate 11 having a large dielectric constant ε. In addition, when the resonance wavelength λ is shortened, the antenna size is also reduced. The optimum parameters in terms of the guide wavelength are ps = 1.3λg, hs = 0.25λg, d = 0.02λg, rd = 0.067λg, rs = 0.3λg.

(A), (B), and (C) of FIG. 17 show examples of mounting the multi-beam antenna 10.
As shown in FIG. 17A, the multi-beam antenna 10 includes a wireless LAN base station 31 (whether indoors or outdoors), and a notebook PC (information terminal) 32 (liquid crystal) as shown in FIG. 17), by mounting on a wireless TV (AV device) 33 as shown in FIG. 17C, interference waves generated by reflection on the wall or the like can be suppressed without increasing the transmission / reception system. can do.

  Here, in the above-described embodiment, the multi-beam antenna 10 having three beams is used. However, the number of beams is not limited to three, and a multi-beam antenna having an arbitrary number of beams can be configured. The parasitic patch antenna element 1 provided at the center is a regular hexagon. However, it is not necessarily a regular polygon, and may be a circle if a multidirectional beam is required.

  For example, as shown in FIG. 18, one parasitic patch antenna element 1 and eight capacitively loaded monopole antenna elements 2 </ b> A to 2 </ b> H arranged on the circumference around the parasitic patch antenna element 1. The 8-beam multi-beam antenna 30 can be configured by selectively switching the feeding or termination of the 8-element capacitively loaded monopole antenna elements 2A to 2H by a feeding circuit (not shown).

  Further, although rectangular capacitively loaded monopole antenna elements 2A to 2H are used as the radiating elements, the capacitively loaded monopole antenna elements 2A to 2H may be circular as in the multi-beam antenna 40 shown in FIG.

  Further, the capacitance loaded monopole antenna elements 2A to 2H can perform matching adjustment by providing a short-circuit pin, but the short-circuit pin can be omitted as in the multi-beam antenna 50 shown in FIG.

  Further, a monopole antenna element without the capacitive electrode 23 may be used instead of the capacitively loaded monopole antenna elements 2A to 2H in the multi-beam antennas 10, 30, and 40.

  Capacitance-loaded monopole antenna elements 2A to 2H do not have protrusions as compared with general monopole antenna elements, so that the height can be reduced.

  In the multi-beam antennas 10, 30, and 40 having the above-described configuration, the parasitic patch antenna element 1 provided at the center is shared as a reflector, so that a plurality of reflectors are not required and the size can be reduced. Further, by adopting a capacitively loaded monopole antenna element 2 as an N element (N: natural number) monopole antenna element arranged on the circumference centered on the parasitic patch antenna element 1, the thickness is further reduced. Can be achieved. The F / B ratio can be improved by selectively feeding the capacitively loaded monopole antenna element 2 as a radiating element and terminating the radiating element by 50Ω. Further, by optimizing the distance d between the center parasitic patch antenna element 1 and the capacitively loaded monopole antenna element 2 and the distance rd between the feeding pin 22 and the shorting pin 24 of the capacitively loaded monopole antenna element 2, a high F / B ratio can be realized.

  Further, since the multi-beam antennas 10 and 20 are formed on the dielectric substrate 11 whose back is covered with the entire conductor 21, there is an advantage that it is easy to mount a switch or the like for switching the beam direction.

It is a typical top view of the example of composition of the multi-beam antenna concerning the present invention. It is a typical longitudinal cross-sectional view of a multi-beam antenna.

the above
It is a typical perspective view which shows the basic composition of the capacity | capacitance loading monopole antenna element which comprises the said multi-beam antenna, and a monopole antenna element. It is a circuit block diagram which shows typically the structure of the electric power feeding circuit of the said multi-beam antenna. It is a characteristic view which shows the input characteristic of the said multi-beam antenna. It is a characteristic view which shows the zx surface radiation directivity in the low resonance frequency f1 in the input characteristic of the said multi-beam antenna. It is a characteristic view which shows the zx surface radiation directivity in the high resonant frequency f2 in the input characteristic of the said multi-beam antenna. It is a characteristic view which shows the xy plane radiation directivity in the low resonance frequency f1 in the input characteristic of the said multi-beam antenna. It is a characteristic view which shows xy plane radiation directivity in the high resonant frequency f2 in the input characteristic of the said multi-beam antenna. It is a figure which shows typically the electric current distribution in the low resonance frequency f1 in the termination conditions a of the said multi-beam antenna. It is a figure which shows typically the electric current distribution in the high resonant frequency f2 in the termination conditions a of the said multi-beam antenna. 3 is a schematic plan view showing structural parameters of the multi-beam antenna 10. FIG. The F / B ratio and horizontal plane directivity when the length of one side of the patch of the capacitively loaded monopole antenna element in the multi-beam antenna is fixed at rs = 10.8 mm and the size ps of the ground plate is changed are shown. FIG. It is a characteristic view which shows F / B ratio and horizontal plane directivity when the magnitude | size hs of a center element is changed by the magnitude | size ps = 48mm of a ground plate. It is a characteristic view which shows F / B ratio and horizontal plane directivity when the space | interval d of a center element and a radiation element is changed. It is a characteristic view which shows F / B ratio and horizontal plane half value width when changing the space | interval rd of the feed pin and short circuit pin of a radiation element. It is a figure which shows the example of mounting of the said multi-beam antenna 10 typically. It is a typical top view of the other structural example of the multi-beam antenna which concerns on this invention. It is a typical top view of the other structural example of the multi-beam antenna which concerns on this invention. It is a typical top view of the other structural example of the multi-beam antenna which concerns on this invention. It is a typical perspective view which shows the structure of the Yagi-Uda antenna used for television reception etc. as a directional antenna. It is a characteristic view which shows the directivity of the said Yagi-Uda antenna.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Parasitic patch antenna element, 2 Capacity loading monopole antenna element, 10, 30, 40 Multi-beam antenna, 11 Dielectric substrate, 21 Ground board, 22 Feeding pin, 20 Monopole antenna element, 23 Capacitance electrode, 24 Short-circuit pin 5 Feeding circuit, WS1, WS2, WS3, SW4 selector switch, R1, R2, R3 Terminating resistor

Claims (3)

A single parasitic patch antenna element;
N element (N: natural number) monopole antenna elements arranged on the circumference centered on the parasitic patch antenna element;
A multi-beam antenna comprising switching means for selectively switching between feeding and termination of the N element (N: natural number) monopole antenna element.   2. The multi-beam antenna according to claim 1, wherein the monopole antenna element is a capacitively loaded monopole antenna element. 3. The multi-beam antenna according to claim 2, wherein the monopole antenna element comprising the capacitively loaded monopole antenna element includes a shorting pin for matching.

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