JPH1090327A - Electric field sensor - Google Patents

Abstract

(57) [Problem] To provide an electric field sensor which does not take in noise or transmit noise to the environment other than reception by an antenna, and whose antenna is compatible with an electric electric field sensor. SOLUTION: An antenna 15 and a sensor head 1 each having a connector 3 which can be connected to and detached from each other,
The electric field sensor is connected by the connector 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a measuring instrument used for measuring radio waves and electromagnetic noise, and more particularly to an antenna for measuring the electric field intensity due to electromagnetic waves and as a receiving antenna for signal radio waves of a specific frequency such as broadcast radio waves. It relates to a functioning electric field sensor.

[0002]

2. Description of the Related Art Information devices and communication devices such as computers,
Alternatively, many electric devices such as FA devices such as robots and controllers for automobiles and railways always have a danger of being affected by malfunctions or the like due to external electromagnetic noise. Therefore, in the field of EMC, it is important to accurately measure the magnitude of noise that affects the external electromagnetic environment and others, the noise generated by itself, and the like.

Conventionally, for the measurement of the electromagnetic noise as described above, a method has been adopted in which reception is performed using an ordinary antenna, and the signal is guided to a measuring device through a coaxial cable and detected. Hereinafter, the electric field sensor according to this method is referred to as an electric electric field sensor.

Recently, a change in the electric field intensity is converted into a change in the light intensity by using an optical element configured to change the intensity of the incident light in accordance with the applied electric field intensity, and the light is received through an optical fiber. Methods have been developed to guide the device to the detector. Hereinafter, the electric field sensor according to this method is referred to as an optical electric field sensor.

[0005] The sensor head of the optical electric field sensor uses a crystal having an electro-optical effect as an optical element for converting an electric field intensity into a change in intensity of transmitted light, and has two types of element structures, a bulk element and a waveguide element. . The latter is 10 compared to the former
More than double the detection sensitivity.

FIG. 5 is a diagram showing a configuration of an optical electric field sensor using the electro-optic effect. FIG. 6 is a diagram showing a configuration of the waveguide type sensor head.

As shown in FIGS. 5 and 6, incident light from the light source 5 to the sensor head 1 through the single mode fiber 11 is incident on the incident optical waveguide 21 and then split into energy by the phase shift optical waveguide 22. Is done. When an electric field is applied, a voltage is induced in the modulation electrode 24 by the dipole antenna 15, and electric field components in the phase-shifted optical waveguide 22 are generated in opposite directions in the depth direction. As a result, the refractive index changes due to the electro-optic effect, and the phase difference between the light waves propagating through the two phase-shifted optical waveguides 22 changes according to the magnitude of the applied electric field. That is, the intensity of the light emitted to the single mode fiber 12 changes in accordance with the applied electric field intensity, and the light intensity change is converted into an electric signal by the light receiver 6, and then the intensity of the applied electric field is measured by the measuring device 7. You.

In the case of an optical electric field sensor, since the sensor head 1 and the photodetector 6 are connected by a single mode fiber 12, there is little attenuation even over long distances, and there is no transmission / reception of noise between the transmission line and the environment. There are such features.

[0009]

SUMMARY OF THE INVENTION An electric field sensor is
This method has been adopted for a long time, and is the most common method. However, there are problems that the electric field distribution is disturbed due to the presence of a coaxial cable or the like over a long distance, and that noise may enter the middle of the coaxial cable.

Also, in the case of an optical electric field sensor, the existence of the coaxial cable 18 from the antenna to the sensor head 1 presents a similar problem except that an optical fiber is used as a transmission line.

Also, the coaxial cable 18 is damaged due to deformation and wear due to routing, and the impedance is apt to change, so that periodic calibration is required or replacement is required.

Further, in the measurement of electromagnetic noise, since the electric electric field sensor and the optical electric field sensor have been used independently in the past, there is no compatibility in the configuration, and mutual comparison in the measurement is not considered. There was a problem that it was not easy.

An object of the present invention is to provide an optical electric field sensor which does not take in noise or transmit noise to the environment other than reception by an antenna and which antenna is compatible with an electric electric field sensor, based on the above problem. It is to be.

[0014]

SUMMARY OF THE INVENTION The present invention is directed to a sensor head, a light source for incident light of a sensor head, and a sensor, wherein the intensity of incident light is changed according to an applied electric field intensity and emitted. A light receiver for detecting light emitted from the head,
A measuring device that measures the electric field strength from the electrical output signal of the receiver,
An optical fiber that forms a light transmission path from the light source to the sensor head and from the sensor head to the light receiver, and an electric field sensor that consists of an antenna that receives an applied electric field and inputs it to the sensor head, can be connected to and disconnected from each other. An antenna and a sensor head having a simple connector are electric field sensors connected by the connector.

According to the present invention, there is provided an optical waveguide device comprising a branch interference type optical waveguide formed on a substrate exhibiting an electro-optical effect, and a modulation electrode arranged near two phase shift optical waveguides of the branch interference type optical waveguide. It is an electric field sensor having a type sensor head.

[0016]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing a first embodiment of the present invention. In FIG. 1, connectors 3 are attached to the dipole antenna 15 and the sensor head 1, respectively. Both are connected through a connector 3. Therefore, a coaxial cable connecting between the dipole antenna 15 and the sensor head 1 becomes unnecessary, and the electromagnetic noise can be measured in a state where there is no room for noise to enter except for the reception by the dipole antenna 15. That is, since the coaxial cable is not used at all, as described above, problems such as deformation, abrasion, and change in impedance due to damage of the coaxial cable, which are problems in the related art, can be avoided.

FIG. 2 is a diagram showing a second embodiment of the present invention. FIG. 3 is a diagram showing a reflective waveguide sensor head constituting the optical electric field sensor of FIG.
A reflection section is provided in the sensor head 2, and incident light and outgoing light pass through the same single mode fiber 11 and are separated by an optical circulator 9. For this reason, since it is sufficient to connect one single mode fiber 11 to the sensor head 2, it is particularly advantageous to install the sensor head 2 and lay an optical fiber over a long distance.

Further, as shown in FIG. 4, the configuration of the optical electric field sensor having the dipole antenna 15 according to the present invention shown in FIG. 1 is solved, and the photoelectric conversion device is replaced with a biconical antenna 16 having the same type of connector 3. A configuration of a field sensor is possible. It is not necessary to explain that the configuration shown in FIG. 2 is completely the same.

As described above, if the connectors are unified to the same type of connector, the connection can be easily changed, and the calibration can be performed by comparing between the electric electric field sensor and the optical electric field sensor or between a plurality of optical electric field sensors. It is also possible to clarify the dependence of antennas by using different antennas.

[0021]

As described above, the electric field sensor according to the present invention is an optical electric field sensor that does not capture noise or emit noise to the environment. Easy. Also, by making it compatible with electric type electric field sensors,
The measurement can be switched to each other, and the characteristics of the electric field sensor can be compared, calibrated, and the dependence of the antenna on the electromagnetic noise measurement can be easily determined.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of an electric field sensor according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of an electric field sensor according to a second embodiment of the present invention.

FIG. 3 is a view showing a reflection type waveguide sensor head constituting the electric field sensor of FIG. 2;

FIG. 4 is a diagram showing a configuration of an optical electric field sensor when the antenna according to the second embodiment of the present invention shown in FIG. 2 is replaced with a biconical antenna.

FIG. 5 is an explanatory diagram showing a configuration of an electric field sensor using an electro-optic effect.

FIG. 6 is an explanatory diagram showing a configuration of a waveguide type sensor head.

[Explanation of symbols]

 Reference numerals 1 and 2 Sensor head 3 Connector 5 Light source 6 Light receiver 7 Measuring instrument 9 Optical circulator 11, 12 Single mode fiber 13 Polarization maintaining fiber 15 Dipole antenna 16 Biconical antenna 18 Coaxial cable 21 Incident optical waveguide 22 Phase shift optical waveguide 23 Outgoing optical waveguide 24 Modulation electrode 25 Substrate 28 Reflector

Claims (2)

[Claims] 1. A sensor head configured to change the intensity of incident light according to an applied electric field intensity and emit light, a light source of incident light of the sensor head, and a light emitted from the sensor head. A photodetector for detection, a measuring device for measuring the electric field intensity from an electric output signal of the photodetector, an optical fiber forming a light transmission path from the light source to the sensor head and from the sensor head to the photodetector, and an application In an electric field sensor including an antenna that receives an electric field and inputs the electric field to the sensor head, the antenna and the sensor head each include a connector that can be connected to and detached from each other, and are connected by the connector. Electric field sensor. 2. The sensor head comprises a branch interference type optical waveguide formed on a substrate exhibiting an electro-optic effect, and a modulation electrode arranged near two phase shift optical waveguides of the branch interference type optical waveguide. 2. The electric field sensor according to claim 1, wherein the sensor head is an optical waveguide element type sensor head.