JPH09162792A - Diversity receiving antenna - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the effect of fading in the diversity receiving antenna system and to prevent production an induction noise, signal leakage and increase in a transmission loss. SOLUTION: Optical modulators 2, 12 are arranged respectively in the vicinity of reception antennas 1, 11 and signals received by the receiving antennas 1, 11 are respectively modulated by the optical modulators 2, 12 into optical intensity signals. The optical intensity signals are coupled by a photocoupler 9 and given to an optical signal detector 7 via an optical fiber. An output (electric signal) of the optical signal detector is given to a receiver 8. The optical signal detector is arranged in the vicinity of the receiver.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diversity receiving antenna device, and more particularly to a diversity receiving antenna device for improving the instability of the reception level.

[0002]

2. Description of the Related Art Generally, when the spatial condition changes during radio wave propagation, the intensity of the radio wave reaching a receiving antenna fluctuates, and as a result, the receiving level becomes unstable. Such a variation in the reception level poses a problem as deterioration of a reception signal, particularly in the field of relay and reception of broadcasting or the joint reception system or communication field.

The phenomenon in which the reception level fluctuates with time is generally called fading. This fading is mainly due to changes in the refractive index of radio waves in the atmospheric layer due to changes in the ionosphere and reflection due to ground. In addition to changes and the like, depending on the radio wave wavelength, the presence of clouds and the rainfall phenomenon also cause fading.

Conventionally, in order to deal with fading, an automatic gain circuit has been added to a receiver (further, a manual attenuator may be used together). However, when the automatic gain circuit is added, As a result, new noise is often generated, and the reception level cannot always be improved practically.

On the other hand, a diversity reception system is known as a reception system for coping with fading. In this diversity receiving method, a pair of receiving antennas are arranged at a predetermined distance, and the receiving signals (radio waves) received by the receiving antennas are combined or the receiving antennas are switched and controlled according to the receiving level. ing.

[0006]

By the way, in the diversity receiving system, since the radio waves are received in a good condition, the receiving antenna is often installed at a high tower or mountain peak. However, if the receiving antenna is installed on a high tower or mountaintop,
The distance between the receiving antenna and the receiver becomes long. That is, the coaxial cable connecting the receiving antenna and the receiver becomes long. As described above, when the coaxial cable becomes long, various problems such as induced noise, signal leakage, and damage to facilities due to lightning strikes occur.

In addition, when the coaxial cable becomes long, it is necessary to arrange an amplifier or the like at every predetermined distance in order to cope with transmission loss.

In any case, in the conventional diversity receiving system, if an attempt is made to receive a radio wave in a good condition, the coaxial cable connecting the receiving antenna and the receiver becomes long, resulting in the generation of inductive noise. However, various problems such as signal leakage and increase in transmission loss occur.

An object of the present invention is to provide a diversity receiving antenna device capable of reducing the influence of fading and preventing the generation of inductive noise, signal leakage and increase in transmission loss.

[0010]

According to the present invention, there are first and second receiving antennas, and the first and second receiving antennas receive the radio wave transmission signals respectively. A diversity receiving antenna device for receiving as a signal, and generating means for generating first and second optical modulation signals according to the first and second received signals, respectively.
An optical coupling unit that obtains an outgoing optical signal according to the first and second optical modulation signals, and a conversion unit that converts the outgoing optical signal into an electrical signal are provided, and the electrical signal is applied to a receiver. A diversity receiving antenna device characterized by the above is obtained.

Further, according to the present invention, the diversity antenna having the first and second receiving antennas and receiving the radio wave transmission signals as the first and second receiving signals at the first and second receiving antennas, respectively. A receiving antenna device,
The first and second signals are respectively received according to the first and second received signals.
Generating means for generating a second optical modulation signal, and the first means.
And conversion means for converting the second optical modulation signal into first and second electric signals, respectively, and combining the first and second electric signals to give to the receiver. A diversity receiving antenna device having the following is obtained.

[0012]

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described below with reference to the drawings.

Referring to FIG. 1, the diversity receiving antenna device shown in the drawing has first and second receiving antennas 1 and 1.
1 and these first and second receiving antennas 1
And 11 are arranged at a predetermined interval from each other.
First and second optical modulators 2 and 12 are arranged near the first and second receiving antennas 1 and 11, respectively. Then, the light from the light source 3 is given to the first modulator 2 through the optical fiber 4 and the polarizer 6. Similarly, the light from the light source 13 is given to the second modulator 12 through the optical fiber 14 and the polarizer 16.

The structure of the optical modulator 2 will be described with reference to FIG.

The illustrated optical modulator 2 is a transmissive optical modulator and includes a substrate 51. The substrate 51 is composed of a lithium niobate crystal that exhibits an electro-optical effect. The incident optical waveguide 52 and the incident optical waveguide 5 are provided on the substrate 51.
A pair of phase shift optical waveguides 53 branched from two, and an output optical waveguide 5 coupling the pair of phase shift optical waveguides 53
4 are formed, and the incident optical waveguide 52, the pair of phase shift optical waveguides 53, and the outgoing optical waveguide 54 constitute an interference type optical waveguide. Each phase shift waveguide 5
Corresponding to No. 3, a modulation electrode 55 is formed in the vicinity thereof, and an electric field is applied to the phase shift optical waveguide 53 by these modulation electrodes 55.

As shown, the incident optical waveguide 52 is connected to the optical fiber 4 (the polarizer 6 is not shown in FIG. 2), and the outgoing optical waveguide 54 is connected via the optical fiber 5 to the phase adjuster 19 (see FIG. Connected to 1). On the other hand, each modulation electrode 55 is connected to the receiving antenna 1.

As described above, light is incident on the optical modulator 2 from the light source 3 via the optical fiber 4. On the other hand, the radio wave (transmission signal) received by the receiving antenna 1 is a voltage signal (first signal).
Received signal) is given to the optical modulator 2. When the above voltage signal is applied to the modulation electrode 55, the incident light on the optical modulator 2 is modulated according to the voltage level of the voltage signal, and is modulated onto the optical fiber 5 as a light intensity signal (first light intensity signal). Is emitted.

The optical modulator 12 also has the same structure as the optical modulator 2, and light from the light source 13 is incident on the optical modulator 12 via the optical fiber 14. On the other hand, the receiving antenna 11
The radio wave received at is given to the optical modulator 12 as a voltage signal (second received signal). This voltage signal is the optical modulator 1
When the light is applied to the second modulation electrode, the incident light on the optical modulator 12 is modulated according to the voltage level of the voltage signal and is emitted onto the optical fiber 15 as a light intensity signal (second light intensity signal).

Referring again to FIG. 1, in the illustrated example, the first
The phase difference between the second light intensity signal and the second light intensity signal is adjusted by the phase adjuster 19. Specifically, the phase adjuster 19
The phase of the first light intensity signal is adjusted so that the phase of the first light intensity signal is in phase with the phase of the second light intensity signal.
The phase adjuster 19 is composed of, for example, an optical fiber, and is connected to the optical fiber 15 by adjusting the length of the optical fiber. In this example, the phase adjuster 19 used is one in which a coil-shaped optical fiber having connectors arranged at predetermined intervals between both ends of the optical fiber is housed in a case. Then, the connector to be connected to the optical fiber 5 was selected and the phase was adjusted. A plurality of optical fibers having different lengths may be used as the phase adjuster, and connectors may be provided at both ends of each optical fiber.

The first light intensity signal whose phase has been adjusted as described above is combined (combined) with the second light intensity signal by the combiner 9.
Is done. The output optical signal from the coupler 9 is given to the optical signal detector 7 via the optical fiber 25, and is converted into an electrical signal here. Then, this electric signal is given to the receiver 8. The optical signal detector 7 is arranged near the receiver 8.

Next, another example of the diversity receiving antenna apparatus according to the present invention will be described with reference to FIG.
In FIG. 3, the same components as those of the antenna device shown in FIG. 1 are designated by the same reference numerals.

Optical modulators 22 and 32 are arranged near the receiving antennas 1 and 11, respectively, and the receiving antennas 1 and 11 are connected to the optical modulators 22 and 32, respectively. The light from the light source 23 is emitted by the optical circulator 37.
And the light from the light source 23 is branched and provided to the optical modulator 22 via the optical fiber 24 and the optical fiber 34 and the phase adjuster 19. To the optical modulator 32.

Here, the configuration of the optical modulator 22 will be described with reference to FIG.

The illustrated optical modulator 22 is a reflection type optical modulator, and includes a substrate 61. The substrate 61 is composed of a lithium niobate crystal that exhibits an electro-optical effect. An input / output optical waveguide 62, a pair of phase shift optical waveguides 63 branched from the input / output optical waveguide 62, and a reflecting portion 66 are formed on the substrate 61.
2, the pair of phase shift optical waveguides 63, and the reflection section 66 constitute an interference optical waveguide. A modulation electrode 65 is formed in the vicinity of each phase shift waveguide 63, and an electric field is applied to the phase shift optical waveguide 63 by these modulation electrodes 65.

The input / output optical waveguide 62 is connected to the optical fiber 24, while each modulation electrode 65 is connected to the receiving antenna 1.

As described above, the light source 23 is included in the light modulator 22.
The light from is incident. On the other hand, the radio wave received by the receiving antenna 1 is given to the optical modulator 22 as a voltage signal.
When the above voltage signal is applied to the modulation electrode 65, the incident light on the optical modulator 22 is modulated according to the voltage level of the voltage signal and is transmitted onto the optical fiber 24 as a light intensity signal (first light intensity signal). Is emitted.

The light modulator 32 also has the same structure as the light modulator 22, and as described above, the light source 2 is included in the light modulator 32.
The light from 3 is incident. On the other hand, the radio wave received by the receiving antenna 11 is given to the optical modulator 32 as a voltage signal. When this voltage signal is applied to the modulation electrode of the optical modulator 32, the incident light on the optical modulator 32 is modulated according to the voltage level of the voltage signal and emitted as a light intensity signal (second light intensity signal). It

Referring again to FIG. 3, the phase of the second light intensity signal is adjusted by the phase adjuster 19, and then the optical branching / combining device 2 is used.
9 given. The first and second optical intensity signals are multiplexed by the optical branching / coupling device 29 and given to the optical circulator 37 via the optical fiber 14.

In the optical circulator 37, the output optical signal from the optical branching / coupling device 29 is given to the optical signal detector 7. In the optical signal detector 7, this output optical signal is converted into an electric signal and given to the receiver 8.

In the example shown in FIG. 3, since the reflection type optical modulator is used as the optical modulator, the incident light to the modulator and the emitted light from the modulator can be propagated to the same optical fiber, and as a result, , The configuration becomes simple.

Still another example of the antenna device according to the present invention will be described with reference to FIG. In FIG. 5, the same components as those shown in FIGS. 1 and 3 are designated by the same reference numerals.

In the illustrated example, as the light source 33, a single laser which emits two linearly polarized lights having polarization planes perpendicular to each other is used. The light from the light source 33 is the optical fiber 14
To the polarization splitter 49, where it is split into two linearly polarized lights. These linearly polarized lights are given to the optical modulators 2 and 22 via the optical fibers 24 and 34, respectively.

The output light from the optical modulators 2 and 22, that is, the first and second optical intensity signals are combined by the optical coupler 9 in the same manner as in the example shown in FIG. The output optical signal from is converted into an electric signal by the optical signal detector 7 and then given to the receiver 8.

In the example shown in FIG. 5, the optical fiber 14 from the light source 33 to the polarization separator 49 is a single mode optical fiber, and the optical fibers 24, 34, 5, and 15 are polarization plane maintaining optical fibers.

As described above, in the example shown in FIG. 5, the light source 3
Since a single laser that emits two linearly polarized lights having polarization planes perpendicular to each other is used as 3, there is no need to use an expensive polarization-maintaining optical fiber as the optical fiber 14.

The optical fiber 14 does not necessarily have to be a single mode optical fiber.

Still another example of the antenna device according to the present invention will be described with reference to FIG. In the antenna device shown in FIG. 6, the same components as those of the antenna device shown in FIG. 5 are designated by the same reference numerals, and the description thereof will be omitted.

In this example, after the output light (first light intensity signal) from the optical modulator 2 is phase-adjusted by the phase adjuster 19, the optical signal detector 27 outputs an electric signal (first electric signal). And the output light (second light intensity signal) from the optical modulator 12 is converted into an electrical signal (second electrical signal) by the optical signal detector 17.
Is converted to Then, these first and second electric signals are combined and then given to the receiver 8.

Still another example of the antenna device according to the present invention will be described with reference to FIG. In the antenna device shown in FIG. 7, the same components as those of the antenna device shown in FIG. 5 are designated by the same reference numerals, and the description thereof will be omitted.

In this example, the output light (first light intensity signal) from the optical modulator 2 is phase-adjusted by the phase adjuster 19 and then supplied to the optical signal detector 7 and the optical modulator 1
The output light (second light intensity signal) from 2 is the optical signal detector 7
Has been given to. That is, in the illustrated example, the optical coupler is not used and only one optical signal detector 7 is provided.

As shown in FIG. 8, this optical signal detector 7
Is provided with a photodiode 70 and a condenser lens 72, and the emission ends of the optical fiber 15 and the optical fiber 5 (the optical fiber from the phase adjuster 19) are positioned on the condenser lens 72. Light emitted from the optical fiber 15 and the light emitted from the optical fiber 5 are condensed by a condenser lens 72, and are formed at another position on the light receiving surface 71 of the photodiode 70. The first and second light intensity signals are respectively the first and second light intensity signals.
After being converted into an electric signal of, the signal is combined as described above and given to the receiver 8.

With reference to FIG. 9, a diversity receiving antenna device for selecting and receiving only one receiving antenna according to the reception levels at the first and second receiving antennas 1 and 11 will be described.

In this example, the output light from the optical modulator 2 (first light intensity signal) is converted into an electric signal (first electric signal) by the photodetector 27, and the output light from the optical modulator 12 is converted. (Second
Light intensity signal) is converted into an electric signal (second electric signal) by the photodetector 17. The intensities of the first and second electric signals are compared by the comparator 10, and only one of the electric signals having high intensity is selectively given to the receiver 8.

In the above example, the space diversity in which the receiving antennas 1 and 11 are arranged at a predetermined interval has been described. However, if the two receiving antennas are directional antennas, radio waves in different directions are received. It can be used as an angle diversity receiving antenna device for.

Further, if two receiving antennas having polarization dependence are used, one for horizontal polarization and the other for vertical polarization, it can be used as a polarization diversity receiving antenna device for cross polarization. it can.

[0046]

As described above, according to the present invention, since the path from the receiving antenna to the receiver is substantially an optical fiber and the signal received by the receiving antenna is transmitted by using the optical signal, the diversity is achieved. Not only the effect of fading, which is a characteristic of the receiving method, can be reduced, but also the generation of induced noise, signal leakage, and increase in transmission loss can be prevented.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining a first example of a diversity receiving antenna device according to the present invention.

FIG. 2 is a diagram for explaining the configuration of the optical modulator shown in FIG.

FIG. 3 is a diagram for explaining a second example of the diversity receiving antenna device according to the present invention.

FIG. 4 is a diagram for explaining the configuration of the optical modulator shown in FIG.

FIG. 5 is a diagram for explaining a third example of the diversity receiving antenna device according to the present invention.

FIG. 6 is a diagram for explaining a fourth example of the diversity receiving antenna device according to the present invention.

FIG. 7 is a diagram for explaining a fifth example of the diversity receiving antenna device according to the present invention.

FIG. 8 is a diagram for explaining the configuration of the optical signal detector shown in FIG.

FIG. 9 is a diagram for explaining a sixth example of the diversity receiving antenna device according to the present invention.

[Explanation of symbols]

 1,11 Receiving antenna 2,12,22,32 Optical modulator 3,13,23,33 Light source 4,5,14,15,24,25,34, Optical fiber 6,16 Polarizer 7,17,27 Light Signal detector 8 Receiver 9 Optical coupler 10 Comparator 19 Phase adjuster 29 Optical branching coupler 37 Optical circulator 49 Polarization separator 51, 61 Substrate 52 Incident optical waveguide 53, 63 Phase shift optical waveguide 54 Emission optical waveguide 55, Reference numeral 65 Modulation electrode 62 Input / output optical waveguide 66 Reflecting portion 70 Photodiode 71 Light receiving surface 72 Condensing lens

Continuation of front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display area H04B 10/06

Claims (15)

[Claims] 1. A diversity receiving antenna apparatus having first and second receiving antennas, wherein the first and second receiving antennas receive radio wave transmission signals as first and second receiving signals, respectively. , Generating means for respectively generating first and second optical modulation signals in response to the first and second received signals, and obtaining an outgoing optical signal in response to the first and second optical modulation signals A diversity receiving antenna device comprising an optical coupling means and a conversion means for converting the emitted optical signal into an electric signal, and applying the electric signal to a receiver. 2. The diversity receiving antenna apparatus according to claim 1, wherein the optical coupling means selects one of the first and second optical modulation signals to obtain the emission optical signal. A diversity receiving antenna device characterized in that 3. The diversity receiving antenna device according to claim 2, wherein the optical coupling means selects one of the first and second optical modulation signals according to a reception level and outputs the signal. A diversity receiving antenna device, characterized in that a light-emitted signal is obtained. 4. The diversity receiving antenna apparatus according to claim 1, wherein the optical coupling means is configured to combine the first and second optical modulation signals to obtain the outgoing optical signal. Diversity receiving antenna device. 5. The diversity receiving antenna apparatus according to claim 4, further comprising a phase adjusting unit that makes the phases of the first and second optical modulation signals in-phase, and the phase adjusting unit includes the generation unit. A diversity receiving antenna device, wherein the diversity receiving antenna device is arranged between the means and the optical coupling means. 6. The diversity receiving antenna device according to claim 5, wherein the phase adjusting means receives at least one of the first and second optical modulation signals, and the phase adjusting means is an optical fiber. A diversity receiving antenna device, comprising: and adjusting the length of the optical fiber so that the first and second optical modulation signals have the same phase. 7. The diversity receiving antenna apparatus according to claim 1, wherein the generating unit receives a light source and light emitted from the light source, and receives the first received signal. A first optical modulator that modulates the outgoing light with one reception signal to generate the first optical modulation signal; and a first optical modulator that receives the outgoing light from the light source and receives the second reception signal. And a second optical modulator that modulates the emitted light with a received signal to generate a second optical modulated signal. 8. The diversity receiving antenna device according to claim 7, wherein the first and second optical modulators each have a substrate having an electro-optical effect, an optical waveguide and a modulation formed on the substrate. Diversity receiving antenna device, characterized in that the light emitted from the light source is given to the optical waveguide, and the first or second received signal is given to the modulation electrode. . 9. The diversity receiving antenna device according to claim 7, wherein the first and second optical modulators are arranged in the vicinity of the first and second receiving antennas, respectively, and the conversion means is provided. Is arranged in the vicinity of the receiver. 10. The diversity receiving antenna device according to claim 7, wherein the light source emits two linearly polarized lights whose planes of polarization are perpendicular to each other, and the two linearly polarized lights are branched and one of the two is polarized. A diversity receiving antenna device comprising: a polarization splitter that gives the emitted light to the first optical modulator and gives the other to the second optical modulator as the emitted light. 11. The diversity receiving antenna device according to claim 10, wherein the light source, the polarization separator, the first and second optical modulators, the optical coupling means, and the conversion means are combined. An optical transmission line is formed, and an optical transmission line connecting the polarization separator and the first and second optical modulators, the first and second optical modulators, and the optical coupling means are provided. The diversity receiving antenna device, wherein each of the optical transmission lines to be connected is a polarization maintaining optical fiber. 12. The diversity receiving antenna apparatus according to claim 11, wherein a transmission line connecting the light source and the polarization separator is a single mode optical fiber. 13. Having first and second receiving antennas,
A diversity receiving antenna device for receiving a radio wave transmission signal as a first reception signal and a second reception signal at the first and second reception antennas, respectively.
Generating means for generating the first and second optical modulation signals in accordance with the received signals, and converting means for converting the first and second optical modulation signals into first and second electric signals, respectively. And a diversity receiving antenna device, characterized in that the first and second electric signals are combined and given to a receiver. 14. The diversity receiving antenna apparatus according to claim 13, wherein the converting means is the first
A first optical signal detector for converting the second optical modulation signal into the first electric signal, and a second optical signal detector for converting the second optical modulation signal into the second electric signal. A diversity receiving antenna device characterized by the above. 15. The diversity receiving antenna device according to claim 13, wherein the conversion means includes a photoelectric conversion section having a predetermined light receiving surface and the first optical modulation signal at a first position of the light receiving surface. And a guide means for guiding the second optical modulation signal to the second position of the light receiving surface, and a diversity receiving antenna device.