JP2002365321A - Field sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a field sensor into which high frequency noise will not enter. SOLUTION: In this field sensor comprising a dipole antenna 1, formed of two conductor bars 1A and 1B arranged linearly in a space 7, while being mutually turned in the opposite directions, the difference in the signals detected from the mutually facing end parts 8 of the conductor bars 1A and 1B is taken as the electric field of the space 7. The conductor bars 1A and 1B are covered with external conductors 2A and 2B, respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric field sensor for detecting an electric field in a space by using a dipole antenna.
In particular, it relates to an electric field sensor that does not contain high-frequency noise.

[0002]

FIG. 3 shows a conventional electric field sensor.
(A) is a perspective view showing the configuration, (B) is (A) of FIG.
3 is an equivalent circuit diagram of FIG. In FIG. 3A, a dipole antenna 1 in a conventional electric field sensor includes conductor rods 1A and 1B linearly arranged in a space 7 in opposite directions.
The end 8 on the side facing the conductor bars 1A and 1B is connected to the input terminal of the differential amplifier 3, and the output terminal of the differential amplifier 3 is connected to the input terminal of the waveform display device 4. Each of the radio signals picked up by the conductor bars 1A and 1B is input to the differential amplifier 3, and the differential amplifier 3 outputs a signal proportional to the electric field in the space 7 by taking the difference between the radio signals. The waveform display device 4 displays the signal output from the differential amplifier 3 as a waveform.

[0003] In FIG. 3 (B), a thick line represents a conductor bar 1.
A, 1B, and the capacitance C is the conductor rod 1A, 1B.
Stray capacitance and resistance R distributed between B and ground E, respectively.
Is the input resistance of the differential amplifier 3. When the dipole antenna 1 is an electric field sensor, a resistor having a large resistance value is used as the resistor R, and the capacitance C and the resistor R
Thus, the radio signals from the conductor bars 1A and 1B are integrated.

[0004]

However, the conventional electric field sensor as described above has a problem that high frequency noise is introduced. 4A and 4B show results of electric field waveform observation by the conventional electric field sensor of FIG. 3, wherein FIG. 4A is a waveform chart of an electric field obtained by a waveform display device, and FIG. 4B is a waveform chart of an electric field generated in space. In each case, the horizontal axis represents time (100 ns / d
iv), the vertical axis is the electric field. That is, in FIG.
In the observation of the electric field waveform, the dipole antenna 1 was disposed in the space 7 of an electric field generator (not shown), and an electric field rising in the space 7 for several hundred ns was generated. A waveform 6B in FIG. 4B is a waveform of a voltage used for forming an electric field from the electric field generator, and the waveform 6B corresponds to a true electric field waveform formed in the space 7.
The waveform 6A in FIG. 4A is from the electric field sensor in FIG. 3, but the high-frequency noise was superimposed on the waveform and the accuracy of waveform observation was poor.

An object of the present invention is to provide an electric field sensor free from high-frequency noise.

[0006]

According to the present invention, there is provided a dipole antenna in which two conductor rods are linearly arranged in space in opposite directions to each other. In an electric field sensor in which the difference between signals detected from the ends on the opposite side is an electric field in the space, it is preferable that each of the conductor bars is covered with an external conductor. Thus, the stray capacitance distributed between the outer conductor and the conductor bar integrates the radio signal, so that high-frequency noise is attenuated.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to embodiments. 1A and 1B show an electric field sensor according to an embodiment of the present invention, in which FIG. 1A is a perspective view showing the configuration, and FIG. 1B is an equivalent circuit diagram of FIG. In FIG. 1A, conductor rods 1A and 1B are covered with coaxial cylindrical outer conductors 2A and 2B, respectively. In FIG. 1B, the capacitance C ₀ is the external conductor 2 indicated by a thick line.
A, 2B and the stray capacitance distributed between the conductor rods 1A, 1B, respectively. Other parts of FIG. 1 are the same as the conventional case of FIG. 3, and the same parts as those of the conventional case are denoted by the same reference numerals, and the detailed description is omitted.

FIGS. 2A and 2B show the results of electric field waveform observation by the electric field sensor of FIG. 1, wherein FIG. 2A is a waveform chart of an electric field obtained by a waveform display device, and FIG. In each case, the horizontal axis represents time (100 ns / div), and the vertical axis represents electric field. That is, in FIG. 1, in observing the waveform of the electric field, the dipole antenna 1 is arranged in a space 7 of an electric field generator (not shown), and several hundred n
An electric field rising at s was generated. The waveform 5B in FIG. 2B is the same as the waveform 6B in FIG. 4B, the waveform of the voltage used to generate the electric field from the electric field generator, and corresponds to the true electric field waveform. . The waveform 5A in FIG. 2A is from the electric field sensor in FIG. 1, but the high-frequency noise has been removed and the accuracy of waveform observation has been improved compared to the related art. This is the outer conductor 2A,
Since the resistance formed in parallel with the capacitance C ₀ distributed between the outer conductors 2A and 2B and the conductor rods 1A and 1B is infinite and high, a radio signal is transmitted between the outer conductors 2A and 2B and the conductor rods 1A and 1B. Each is integrated and the high frequency noise is attenuated.

[0009]

As described above, according to the present invention, by covering each of the conductor rods with an external conductor, high-frequency noise is removed and the accuracy of electric field waveform observation is improved.

[Brief description of the drawings]

FIG. 1 shows an electric field sensor according to an embodiment of the present invention;
(A) is a perspective view showing the configuration, (B) is (A) of FIG.
Equivalent circuit diagram of

2A and 2B show the results of an electric field waveform observed by the electric field sensor of FIG. 1; FIG. 2A is a waveform diagram of the electric field obtained by a waveform display device;
(B) is a waveform diagram of the electric field generated in the space.

3A and 3B show a conventional electric field sensor, in which FIG. 3A is a perspective view showing a configuration thereof, and FIG. 3B is an equivalent circuit diagram of FIG.

4A and 4B show results of electric field waveform observation by the electric field sensor shown in FIG. 3, wherein FIG.
(B) is a waveform diagram of the electric field generated in the space.

[Explanation of symbols]

1: dipole antenna, 1A, 1B: conductor rod, 2A,
2B: outer conductor, 8: end

Claims (1)

[Claims] 1. A dipole antenna in which two conductor rods are linearly arranged in opposite directions in a space, and a difference between signals detected from an end of the dipole antenna on a side opposite to the conductor rods is determined. An electric field sensor for an electric field, wherein each of the conductor bars is covered with an external conductor.