JPH0786825A - Directional diversity antenna - Google Patents

Abstract

PURPOSE:To provide a directional diversity antenna capable of controlling directivity. CONSTITUTION:On the surface of a printed board 45 whose backside is covered with a ground plate 44, a radiation element 42a and the radiation element 42b are provided with the distance of 1/4 the length of the wavelength l of microwaves. The radiation element 42a and the radiation element 42b are connected by micro strip lines 53 and 54 and the phase shift circuit 1 of l/4. The micro strip line 53 is connected to the micro strip line 55 at a connection point B and the micro strip line 54 is connected to the micro strip line 56 at the connection point C. One end of the micro strip line 51 connected to the micro strip line 52 at the connection point A is connected to an antenna output terminal 43. Electronic switches 11 and 12 are provided between the micro strip line 52 and the micro strip lines 55 and 56.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to directional diversity antennas, and more particularly to directional diversity antennas for receivers operating in the quasi-microwave band.

[0002]

2. Description of the Related Art A diversity antenna is a receiving antenna for performing high-quality communication by obtaining two or more signals with a fading situation having a correlation as small as possible by some method and selecting or combining them. Furthermore, we used the fact that the fading situation of the received signal electric field differs depending on the position of each antenna that constitutes the diversity antenna, the plane of polarization of the incoming radio wave, the angle of incidence for each propagation path of the radio wave, the frequency of the signal or the temporal difference. It is a thing.

By the way, there is a microstrip line antenna as described on page 109 of the Antenna Handbook published by Ohmsha, edited by The Institute of Electronics and Communication Engineers. FIG. 5 is a diagram showing an outline of the microstrip line antenna. In particular, FIG. 5A is a plan view of the microstrip line antenna, and FIG. 5B is a side view of the microstrip line antenna.

Referring to FIG. 5, the back side is ground ground plate 44.
An antenna output terminal 43 for outputting a microwave frequency signal to the receiver is provided on the surface of the printed circuit board 45 covered with. The antenna output terminal 43 is connected to one end of the microstrip line 41, and the other end of the microstrip line 41 is terminated by the radiating element 42. Next, the operation will be described. When microwaves are incident on the radiating element 42, a magnetic current flows between the periphery of the radiating element 42 and the ground ground plane 44. This magnetic current reaches the antenna output terminal 43 via the microstrip line 41. This allows the antenna output terminal 4
3 outputs a radio frequency signal to the receiver.

[0005]

The microstrip line antenna shown in FIG. 5 has only one radiating element, and therefore, it is caused by multipath delay dispersion or standing waves caused by propagation of radio frequency signals. There have been problems such as difficulty in receiving radio frequency signals in valleys of radio waves.

Therefore, the present invention solves the above problems and provides a directional diversity antenna capable of receiving a radio frequency signal in the quasi-microwave band.

[0007]

A directional diversity antenna according to the invention of claim 1 is a diversity antenna for outputting a radio frequency signal in the microwave band to a receiver, and a plurality of antennas are provided in a space or on a main plate. Of the radiating element, a phase shifter connected between the radiating elements, a switch circuit connected to the phase shifter, and an antenna output terminal connected to the switch circuit.

In the second aspect, each radiating element of the first aspect is provided so as to have symmetry with respect to the phase shifter.

According to a third aspect of the present invention, the phase shifter of the first aspect includes a lumped constant circuit, a strip line, or a combination thereof, and the phase shift angle of the phase shifter corresponds to the distance between the radiating elements. The sum of and is equal to the phase shift angle corresponding to an integral multiple of the half wavelength of the microwave.

According to a fourth aspect, at least one switch circuit according to the first aspect is provided between the antenna output terminal and each radiating element.

In a fifth aspect, the radiating element according to the first aspect is a printed circuit board such as a linear antenna or a plate antenna such as a unipole antenna, a helical antenna or an inverted F-shaped antenna, a microstrip antenna, a batch antenna or a slot antenna. Includes an antenna provided above, or a combination of these.

In a sixth aspect of the present invention, the directional diversity antenna according to the first aspect of the present invention further includes at least one circuit for impedance matching between each radiating element and the antenna output terminal.

[0013]

The directional diversity antenna according to the present invention can change the directivity by switching the phase shifter provided between a plurality of radiating elements.

[0014]

1 is a schematic view of a directional diversity antenna according to a first embodiment of the present invention. In particular, FIG. 1 (a) is a plan view of the directional diversity antenna. FIG. 1B is a side view of the directional diversity antenna.

Referring to FIG. 1, the bottom side is ground ground plate 44.
The surface of the printed circuit board 45 covered with the radiating element 42 is
a and the radiating element 42b are provided at a distance of ¼ of the wavelength λ of the microwave. The radiating element 42a and the radiating element 4
A λ / 4 phase shift circuit (hereinafter, abbreviated as λ / 4 circuit) 1 is provided between the 2b and 2b. Radiating element 42a and λ / 4
The circuit 1 is connected by a microstrip line 53, and the radiating element 42b and the λ / 4 circuit 1 are connected by a microstrip line 54. The microstrip lines 53 and 54 have connection points B and C, respectively, and are connected to the L-shaped microstrip lines 55 and 56 at the connection points B and C, respectively. The antenna output terminal 43 is provided on the side where the microstrip lines 55 and 56 are provided.
One end of is connected. The other end of the microstrip line 51 is connected to the microstrip line 52 at the connection point A.
, And the two connected microstrip lines 51, 52 are T-shaped. The electronic switch 11 is provided between the microstrip line 52 and the microstrip line 55, and the electronic switch 12 is provided between the microstrip line 52 and the microstrip line 56. The microstrip lines 51 to 56 are connected to the radiating elements 42a and 42a.
It can also play a role of impedance matching between b and the antenna output terminal 43.

FIG. 2 is a diagram for explaining the operation of the directional diversity antenna according to the first embodiment of the present invention. The operation will be described below.

When both the electronic switches 11 and 12 are turned on, the radiating elements 42a and 42b are excited in the same phase. Therefore, sharp directivity appears in the front direction 31 with respect to the left-right direction of the antenna. When the electronic switch 11 is in the ON state and the electronic switch 12 is in the OFF state, the radiating element 42a is excited outward in the opposite phase and the radiating element 42b is excited outward in the same phase. Therefore, the directivity of the antenna appears as a sharp directional characteristic in the left front direction 32.
Explaining this in detail, first, the radiating element 4
The electric field outside 2b is a combination of the electric fields emitted from the radiating elements 42a and 42b. When the electronic switch 11 is in the ON state, the phase of the radio wave fed to the radiating element 42b is λ /
4 The circuit 1 is delayed by 90 ° from that supplied to the radiating element 42a, and the phase of the electric field radiated from the radiating element 42a to the outside of the radiating element 42b is also the spatial distance between the radiating element 42a and the radiating element 42b. Is λ / 4, the phase is 90 ° behind that of the element fed to the radiating element 42a. That is, outside the radiating element 42b, in-phase electric fields are combined, so that the electric field becomes stronger. Similarly, on the outside of the radiating element 42a, electric fields of opposite phases are combined, so that the electric field becomes weak. Therefore, when the electronic switch 11 is on and the electronic switch 12 is off, the directivity of the antenna sharply appears in the left front direction 32. When the electronic switch 11 is in the off state and the electronic switch 12 is in the on state, the radiating element 42a is excited outward in the same phase, and the radiating element 42b is excited.
Is excited in the opposite phase to the outside. Therefore, the directivity of the antenna appears as a sharp directional characteristic in the right front direction 33.

By controlling the on / off states of the electronic switches 11 and 12 in this manner, the antenna can have directivity in the three directions of front, left front, and right front.

FIG. 3 is a schematic block diagram of a diversity antenna according to a second embodiment of the present invention.
FIG. 3A is a plan view of the diversity antenna, and FIG. 3B is a side view of the diversity antenna.

Referring to FIG. 3, the back side is ground ground plate 44.
Radiating elements 42a, 42b, 42c, and 42d are provided at intervals of λ / 4 at four corners of the surface of the printed circuit board 45 covered with. The radiating elements 42a, 42b, 42c,
The λ / 4 circuit 1 is provided in the center of 42d. The radiating elements 42a and 42c are connected by a microstrip line 58, and the radiating elements 42b and 42d are connected by a microstrip line 59. The microstrip line 58 has a connection point D, and one end thereof is connected to the microstrip line 53 connected to the λ / 4 circuit 1. The microstrip line 59 has a connection point E and has one end connected to the microstrip line 54 connected to the λ / 4 circuit 1. The microstrip lines 53 and 54 have connection points B and C, respectively, and the configuration from the connection points B and C to the antenna output terminal 43 is almost the same as that of the embodiment shown in FIG. The only different parts are radiating elements 42a, 4
Since 2b, 42c, and 42d are provided on the printed circuit board 45, the microstrip line 57 connecting the microstrip line 52 and the antenna output terminal 43 is formed as shown in FIG.
It is longer than the microstrip line 51 shown in FIG. Incidentally, the microstrip lines 52 to 59
Can also play a role of impedance matching between the radiating elements 42a, 42b, 42c, 42d and the antenna output terminal 43.

Next, the operation will be described. Since the distance between the radiating element 42a and the radiating element 42c is λ / 4, the radiating element 42a and the radiating element 42c are excited in the same phase. Since the radiating element 42b and the radiating element 42d have the same relationship, the antenna should exhibit sharp directivity in the front direction with respect to the vertical direction. On the other hand, the distance between the radiating elements 42a and 42c and the radiating elements 42b and 42d is also λ / 4, but the directivity of the antenna changes depending on the on / off states of the electronic switches 11 and 12. That is, if both the electronic switches 11 and 12 are in the ON state, the radiating element 42
The a and 42c and the radiating elements 42b and 42d are excited in the same phase. Therefore, the directivity of the antenna shows a sharp directional characteristic in the front direction 31 shown in FIG. This directional characteristic is sharper than that of the embodiment shown in FIG. When the electronic switch 11 is in the on state and the electronic switch 12 is in the off state, the radiating elements 42a and 42c are excited outward in the opposite phase, and the radiating elements 42b and 42d are excited outward in the same phase. Therefore, the directivity of the antenna is the left-front direction 32 shown in FIG. 2 with respect to the left-right direction, but shows a sharper directional characteristic than the embodiment shown in FIG. When the electronic switch 11 is in the off state and the electronic switch 12 is in the on state, the radiating elements 42a and 42c are excited outward in the same phase, and the radiating elements 42b and 42d are excited outward in the opposite phase. Therefore, although the directivity of the antenna is the right front direction 33 shown in FIG. 2 with respect to the left-right direction, it shows sharper directivity characteristics as compared with the embodiment shown in FIG.

As described above, also in this embodiment, by controlling the on / off states of the electronic switches 11 and 12,
The antenna can be provided with sharper directivity than in the embodiment shown in FIG. 1 and directivity in three directions of front, left front, and right front.

FIG. 4 is a schematic block diagram of a diversity antenna according to a third embodiment of the present invention.
FIG. 4A is a plan view of the diversity antenna and a side view of the diversity antenna. With reference to FIG. 4, portions different from the embodiment shown in FIG. 3 will be described.

The radiating element 42a and the radiating element 42c are not connected by a microstrip line, but the λ / 4 circuit 2 is provided. The λ / 4 circuit 2 and the radiating element 42a are connected by the microstrip line 66, and the λ / 4 circuit 2 and the radiating element 42c are connected by the microstrip line 67. The microstrip line 66 is connected to the L-shaped microstrip line 62 at the connection point H, and the microstrip line 67 is connected to the L-shaped microstrip line 63 at the connection point I. One end of the microstrip line 53 that is not connected to the λ / 4 circuit 1 is connected to the microstrip line 60 at a connection point F. Electronic switches 15 and 14 are provided between the microstrip line 60 and the microstrip lines 63 and 62, respectively.

Similarly, radiating element 42b and radiating element 42d
To the microstrip line,
/ 4 circuit 3 is provided. The λ / 4 circuit 3 and the radiating element 42b are connected by the microstrip line 68, and the λ / 4 circuit 3 and the radiating element 42d are connected by the microstrip line 69.
Connect with. The microstrip line 68 is connected to the L-shaped microstrip line 64 at the connection point J, and the microstrip line 69 is connected to the L-shaped microstrip line 63 at the connection point K. One end of the microstrip line 54 which is not connected to the λ / 4 circuit 1 is connected to the microstrip line 6 at a connection point G.
Connected to 1. Between the microstrip line 61 and the microstrip lines 64 and 65,
Electronic switches 17, 18 are provided. The microstrip lines 52 to 57 and 60 to 69 are connected to the radiating elements 42a, 42b, 42c and 42d and the antenna output terminal 4 respectively.
It can also play the role of impedance matching between the three.

Next, the operation will be described. If the electronic switches 14, 15, 17, 18 are on, this state is the same as the second embodiment shown in FIG. That is,
When both electronic switches 11 and 12 are on,
The radiating elements 42a and 42c and the radiating elements 42b and 42d are excited in the same phase. Therefore, the antenna exhibits sharp directivity in the forward direction. When the electronic switch 11 is on and the electronic switch 12 is off, the radiating element 42a,
42c is excited in the opposite phase in the outward direction, and the radiating element 42b,
42d is excited in the same phase in the outward direction. Therefore, the directivity of the antenna shows a sharp directional characteristic in the front left direction.
When the electronic switch 11 is in the off state and the electronic switch 12 is in the on state, the radiating elements 42a and 42c are excited outward in the same phase, and the radiating elements 42b and 42d are excited outward in the opposite phase. Therefore, the directivity of the antenna is
A sharp directional characteristic is shown in the front right direction.

Next, the electronic switches 11 and 12 are turned on, and the states of the electronic switches 14, 15, 17 and 18 are controlled. First, when the electronic switches 14 and 17 are in the ON state and the electronic switches 15 and 18 are in the OFF state, the radiating elements 42a and 42b are excited in the outward phase in the opposite phase, and the radiating elements 42c and 42d are excited in the outward direction in the same phase. To be done. Therefore, the directivity of the antenna shows a sharp directional characteristic in the front lower direction. When the electronic switches 14 and 17 are off and the electronic switches 15 and 18 are on, the radiating element 42
a and 42b are excited outward in the same phase, and the radiating element 42a
c and 42d are excited in the opposite phase in the outward direction. Therefore, the directivity of the antenna shows a sharp directional characteristic in the upper front direction.

Next, the above matters will be combined.
That is, when the electronic switches 11, 14, 17 are in the on state and the electronic switches 12, 15, 18 are in the off state, the directivity of the antenna shows a sharp directional characteristic in the lower left direction. When the electronic switches 11, 15 and 18 are in the ON state and the electronic switches 12, 14 and 17 are in the OFF state, the directivity of the antenna shows a sharp directional characteristic in the upper left direction. When the electronic switches 12, 14, 17 are on, the electronic switch 1
When 1, 15, 18 are in the off state, the directivity of the antenna shows a sharp directional characteristic in the lower right direction. Electronic switch 1
2, 15, 18 are in the ON state, the electronic switch 11, 1
When the antennas 4 and 17 are off, the directivity of the antenna shows a sharp directional characteristic in the upper right direction.

As described above, the electronic switches 11, 12,
By controlling the on / off states of 14, 15, 17, and 18, it is possible to control the directivity in nine directions, which is a combination of the forward direction and the vertical and horizontal directions.

In this embodiment, the case where the microstrip antenna is used as the radiating element has been described. However, as the radiating element, a linear antenna such as a unipole antenna, a helical antenna, an inverted F-shaped antenna or a plate antenna, or The same effect can be obtained by using an antenna provided on a printed circuit board such as a batch antenna or a slot antenna, or a combination thereof.

The same effect can be obtained by using a microstrip line, a lumped constant circuit, a distributed constant circuit, or the like as the phase shift circuit. The phase shift angle of the phase shift circuit is related to the distance between the antenna radiating elements. Just decide.

Further, even if a part of the electronic switch circuit is deleted or added depending on the required directivity, the required directivity can be obtained.

Further, in order to match the impedance, the microstrip line may be provided with the role in the embodiment, but another matching circuit is provided between the radiating element and the phase shifter or the phase shifter is connected. It may be provided between the output terminals.

[0034]

As described above, according to the present invention, since the directivity can be controlled, good reception can be performed even in the valley of the standing wave in the propagation of the low frequency signal. The antenna diversity effect can be realized.

[Brief description of drawings]

FIG. 1 is a schematic block diagram of a diversity antenna according to a first embodiment of the present invention.

FIG. 2 is a diagram for explaining the directivity of the diversity antenna according to the embodiment of the present invention.

FIG. 3 is a schematic block diagram of a diversity antenna according to a second embodiment of the present invention.

FIG. 4 is a schematic block diagram of a diversity antenna according to a third embodiment of the present invention.

FIG. 5 is a schematic block diagram of a conventional microstrip antenna.

[Explanation of symbols]

1, 2, 3 λ / 4 phase shift circuit 11, 12, 14, 15, 17, 18 Electronic switch 41, 51, 52, 53, 54, 56, 57, 58, 5
9, 60, 61, 62, 63, 64, 65, 66, 6
7, 68, 69 Microstrip line 42, 42a, 42b Radiating element 43 Antenna output terminal 44 Ground ground plate 45 Printed circuit board

Claims (6)

[Claims] 1. A directional diversity antenna for outputting a radio frequency signal in the microwave band to a receiver, the plurality of radiating elements provided in a space or on a ground plane, and a phase shift connected between the radiating elements. Directional diversity antenna including a switch, a switch circuit connected to the phase shifter, and an antenna output terminal connected to the switch circuit. 2. The directional diversity antenna according to claim 1, wherein each of the radiating elements is provided so as to have symmetry with respect to the phase shifter. 3. The phase shifter includes a lumped constant circuit, a strip line, or a combination thereof, and calculates a sum of a phase shift angle of the phase shifter and a phase shift angle corresponding to an interval between the radiating elements. The directional diversity antenna according to claim 1, wherein the phase shift angle is equal to an integral multiple of a half wavelength of the microwave. 4. The directional diversity antenna according to claim 1, wherein at least one switch circuit is provided between the antenna output terminal and each of the radiating elements. 5. The radiating element is a unipole antenna,
A linear antenna such as a helical antenna or an inverted F-shaped antenna or a plate-shaped antenna, an antenna provided on a printed circuit board such as a microstrip antenna, a batch antenna, a slot antenna, or a combination thereof. Directional diversity antenna. 6. The directional diversity antenna according to claim 1, further comprising at least one circuit for impedance matching between each of the radiating elements and the antenna output terminal.