JP2000059128A - Diversity antenna - Google Patents

Abstract

PROBLEM TO BE SOLVED: To receive both satellite waves and ground station waves of the same frequency band with excellent sensitivity. SOLUTION: This antenna is provided with a first antenna part 1 provided with radiation characteristics strong in a vertical direction to a horizontal plane and a second antenna part 2 provided with the radiation characteristics strong in a direction tilted from the vertical direction. A switching circuit 4 for receiving the reception signals of the antenna part of excellent reception sensitivity corresponding to the reception sensitivity of the first and second antenna parts 1 and 2 is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diversity antenna having at least two or more antenna units and capable of receiving, for example, both a wave received from a satellite in the same frequency band and a wave received from a ground station. More specifically, the antenna unit has an antenna unit that easily receives a wave received from a satellite and an antenna unit that easily receives a wave received from a ground station. The present invention relates to a diversity antenna that can receive signals with higher sensitivity in accordance with a received wave.

[0002]

2. Description of the Related Art Conventionally, for example, in a long-distance wireless transmission path, since the reception level generally fluctuates greatly depending on the location due to fading, diversity levels have been used to prevent the fluctuation of the reception level. I have. Conventional diversity antennas are, for example, to arrange several antennas having the same structure at predetermined intervals, to switch to an antenna in an optimal reception state, or to combine the outputs of a plurality of antennas in a phase-combined manner to transmit and receive sensitivity. Is configured to prevent fluctuations.

[0003] On the other hand, been developed in recent years is a digital audio system, for example, the frequency band of the L-band (for example, f ₁ ~
f ₃ ), f _{1 to} f ₂ are broadcast as ground waves by a ground station, f _{2 to} f ₃ are broadcast as satellite waves from satellites, and receiving antennas corresponding to the bands of f _{1 to} f ₃ are used. A system that receives both terrestrial station waves and satellite waves by using satellites has been considered. This system uses Eureka 147
It is called a DAB (Digital Audio Broadcasting) system, and is a hybrid system of a satellite and a ground station. Furthermore, especially in areas where it is difficult to receive radio waves from satellites, such as shadows of high-rise buildings, under highways, or in the mountains, there is also a method in which a terrestrial relay station that has once received satellite broadcast waves retransmits at the same frequency. Attempted.

[0004] Even with such a satellite wave or a ground station wave, the reception sensitivity greatly varies depending on the location such as the shadow of a building, so that a diversity antenna may be used.

[0005]

As described above, in the conventional diversity antenna, antennas having the same structure are arranged at regular intervals, and the antenna having the higher sensitivity or a combined wave from both antennas is used. It is structured to receive. However, as described above, in an antenna receiving both a satellite wave and a ground station wave, the traveling direction of the received wave of the satellite wave and the ground station wave comes from the sky, while the reception sensitivity varies depending on the location. Radio waves and horizontal direction (horizontal direction)
The directivity of the antenna is different from the radio wave coming from the antenna.To receive both the radio wave from the satellite wave and the radio wave from the ground station with high sensitivity, the effect can be obtained even if multiple antennas with the same structure are installed and switched. There is a problem that it cannot be sufficiently improved.

The present invention has been made in view of such a situation, and an object of the present invention is to provide a diversity antenna capable of receiving a satellite wave or a ground station wave in the same frequency band with high sensitivity.

[0007]

SUMMARY OF THE INVENTION A diversity antenna according to the present invention has a first antenna portion having a strong radiation characteristic (directivity) in a direction perpendicular to a horizontal plane, and a strong radiation characteristic in a direction inclined from the vertical direction. A second antenna unit having (directivity characteristics), and a switching circuit for receiving a reception signal of the antenna unit having the superior reception sensitivity according to the reception sensitivity of the first and second antenna units. I have.

Here, having a strong radiation characteristic (directional characteristic) in a direction inclined from the vertical direction means having a directional characteristic in a direction different from the vertical direction, for example, from a horizontal direction (90 °) to a vertical direction. With a center in a direction of about 45 ° with respect to.

With this configuration, an antenna capable of receiving both a satellite wave and a terrestrial station wave can receive a satellite wave by using an antenna having directivity in the direction of the satellite when receiving a satellite wave. In the case of receiving ground station waves, it is possible to automatically switch to the antenna unit having a directional characteristic in the horizontal direction and receive it, so even in a hybrid system that transmits and receives both satellite and ground station radio waves,
It can transmit and receive with very high sensitivity.

[0010] Specifically, the first antenna unit has a T
An antenna beam pattern of the M ₁₁ mode, the second
Can be configured by a combination of antenna units having an antenna beam pattern of a higher-order mode.

A plurality of at least one of the first antenna section and the second antenna section are provided, and each of the antenna sections has a structure which can be switched to one having high sensitivity by the switching circuit. Even if there is a difference in sensitivity depending on the location for the wave and / or for the ground station wave, an optimum antenna unit can be used according to the location, and the sensitivity can be further improved.

[0012]

Next, a diversity antenna according to the present invention will be described with reference to the drawings.

FIG. 1 shows a diversity antenna according to the present invention.
As shown in FIG. 1, a first antenna unit 1 having a strong radiation characteristic (directivity) in a direction perpendicular to a horizontal plane and a strong radiation characteristic (directivity) in a direction inclined from the vertical direction are shown in FIG. And a switching circuit for receiving a reception signal of the antenna unit having the higher reception sensitivity according to the reception sensitivity of the first and second antenna units 1 and 2. 4 are provided.

The first antenna section 1 is a patch antenna formed of a conductive film 1a provided on a dielectric substrate 3 made of, for example, ceramics, and can transmit and receive an L-band frequency band and has a directional characteristic. so it becomes beam pattern of the TM ₁₁ mode which is a fundamental mode, for example, when the relative dielectric constant of the dielectric substrate 3 is 20, 9-12
It is formed to have a size of about 9 mm to 12 mm and a thickness of about 5 to 10 μm. On the back surface of the dielectric substrate 3,
The ground plate 3a is provided by a metal film or the like. Through holes are provided in the dielectric substrate 3 and the ground plate 3a on the back surface side of the conductor film 1a, and the feeder line 5a is connected to the conductor film 1a via the through holes, and the feeder line 5a is connected to the switching circuit 4 Is connected to the changeover switch amplifier. The first antenna unit 1 has the same dimensions as a normal antenna that transmits and receives in a desired frequency band. As shown in FIG. 2A, the first antenna unit 1 has a directional characteristic in a direction perpendicular to the horizontal plane (θ = 0). As a result, it is possible to receive a signal with high sensitivity with respect to a received signal wave from a direction perpendicular to a horizontal plane (upward), such as a received radio wave from a satellite.

Similarly to the first antenna unit 1, the second antenna unit 2 is provided on the dielectric substrate 3 so that a beam pattern of, for example, a TM ₂₁ mode operating in a higher-order mode for the L band is formed. For example, it is formed by providing a conductive film 2a having a diameter of about 17 to 25 mmφ and a thickness of about 5 to 10 μm on the dielectric substrate 3 described above. The fact that the power supply line 5b is connected to the back surface of the conductive film 2a through the through holes of the dielectric substrate 3 and the ground plate 3a
This is the same as the first antenna unit 1 described above. The power supply line 5b is also connected to a changeover switch amplifier that is the changeover circuit 4. The second antenna unit 2 has the same structure as that of the TM ₁₁ except that the shape of the conductive film 2a and the connection position of the feeder line 5b are changed so that a higher-order mode beam pattern is obtained.
It has the same structure as the patch antenna of the mode beam pattern. This second antenna unit 2 is shown in FIG.
As shown in FIG. 2, no beam pattern is formed in the vertical direction with respect to the horizontal plane, but from θ = ± 30 ° to the horizontal direction (θ =
A beam pattern is formed in a direction between ± 90 °), and a received radio wave from this direction can be efficiently received. That is, it is possible to efficiently receive the received radio wave from the ground station that propagates from the lateral direction.

First antenna unit 1 and second antenna unit 2
Is not particularly limited, and can be arranged side by side. However, if spaced at lambda _0/4, it becomes more effective.

As shown in an equivalent circuit diagram of FIG. 3, for example, the changeover switch amplifier 4 includes a changeover switch 41 and an amplifier 42. The input portions of the changeover switch 41 have first and second switches, respectively. The feeder lines 5a and 5b connected to the antenna units 1 and 2 are input, and the switch 41 is used to input any received radio wave. The changeover switch 41 can be configured so that, for example, the levels of the reception signals of the first and second antenna units are compared by a comparator and automatically connected to the larger one, or can be manually switched. . The amplifier 42 amplifies a signal within a predetermined band of the received radio wave in the same manner as the normal signal processing, and the output is connected to the signal processing circuit via the connection line 5c so that the signal is processed. ing.

According to the diversity antenna of the present invention, the first antenna section has a directional characteristic upward,
It is possible to receive radio waves received from satellites with particularly high sensitivity. On the other hand, the second antenna unit has a directional characteristic in the lateral direction, and can receive a radio wave from the lateral direction, that is, a ground station wave with particularly high sensitivity. Therefore, in a place where it is difficult to receive a satellite wave, it is possible to use a ground station wave antenna unit to receive a received radio wave received and retransmitted by the ground station. For example, when broadcasting from a satellite and broadcasting from a ground station are performed in the L band, the first antenna unit is used for broadcasting from a satellite, and the second antenna is used for broadcasting from a ground station. By switching the receiving antenna unit to the above antenna unit, both broadcasts can be received with high sensitivity. Therefore, even in the case of being used by a car or a pedestrian, or fixedly used in a building, the antenna unit can be freely switched to a highly sensitive antenna unit according to the location.

Further, in the above-described example, the first antenna unit and the second antenna unit are each constituted by one. However, for the satellite wave and / or the terrestrial station wave, two antennas are provided at regular intervals. By configuring more than two antenna units and switching to a more sensitive antenna unit between them,
It can also function as the original diversity antenna.

[0020]

According to the present invention, as described above, the antenna has an antenna part that radiates strongly in the upward direction and an antenna part that radiates strongly in the lateral direction, and can be switched and used according to its sensitivity. In a place where radio waves arriving from satellites and radio waves arriving from ground stations are mixed,
Any of the radio waves can be received with high sensitivity, which is particularly effective.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of one embodiment of a diversity antenna of the present invention.

FIG. 2 is a diagram illustrating an example of a beam pattern of first and second antenna units in FIG. 1;

FIG. 3 is a block diagram of an example of a changeover switch amplifier of FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 1st antenna part 2 2nd antenna part 4 Changeover switch amplifier

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5J021 AA02 AA13 AB06 DB04 EA01 EA04 FA21 FA26 FA31 GA01 GA08 HA05 HA06 HA10 5J047 AA03 AB10 FD00 FD01 5K059 CC05 DD02 DD16 DD27

Claims (3)

[Claims] A first antenna unit having a strong radiation characteristic in a direction perpendicular to a horizontal plane; a second antenna unit having a strong radiation characteristic in a direction inclined from the vertical direction;
And a switching circuit for receiving a reception signal of the antenna unit having the higher reception sensitivity in accordance with the reception sensitivity of the second antenna unit. Wherein said first antenna section has an antenna beam pattern of the TM ₁₁ mode, the second antenna portion, the diversity antenna according to claim 1, further comprising an antenna beam pattern of the higher order mode. 3. The switching circuit according to claim 1, wherein a plurality of at least one of the first antenna unit and the second antenna unit are provided, and each of the antenna units can be switched to one having high sensitivity by the switching circuit. Diversity antenna.