JPH0715241A - Amplitude modulator - Google Patents

Abstract

PURPOSE:To reduce a loss and to modulate an amplitude by controlling the no load Q of a resonator at an interdigital band-pass filter composed of a high- temperature super-conductive microstrip line resonator. CONSTITUTION:At the interdigital band-pass filter, which is composed of a high-temperature superconductive microstrip line 1, mutually inversely parallelly coupling resonators, for which one resonator is short and the other resonator is open, provided with the length of a 1/4 wavelength, the loss of insertion can be changed by changing the superconductive microstrip line from a superconductive state to a normally conductive state at high speed by irradiating the line with light. On the other hand, by increasing the number of filter steps and changing the combination of light irradiation, the amplitude modulator can be used as the modulator of the variable amplitude provided with a filter function.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an amplitude modulator, and more particularly to a modulator which requires band limitation for an output modulated wave.

[0002]

2. Description of the Related Art Conventionally, a modulator of this type is usually constructed by using a switching element such as a diode. The spectrum of is unnecessarily spread out of the band, which causes interference to other lines. Therefore, a method has been taken to prevent unnecessary spread spectrum outside the band by installing a bandpass filter after the modulator.

Such a method is described in "Communication Transmission Engineering," written by Gen Marubayashi, edited by the Institute of Electronics and Communication Engineers, IEICE Conference Series F-.
5, Corona Publishing Co., 1981, P. 87 ”.

[0004]

This conventional modulator using a diode requires two functional elements, a diode and a bandpass filter, resulting in a large insertion loss and a large shape. There are drawbacks.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an amplitude modulator capable of high-speed amplitude modulation by controlling insertion loss, that is, no-load Q.

[0006]

The amplitude modulator of the present invention comprises:
A high-temperature superconductor having a length of 1/4 wavelength provided on a dielectric substrate is used, and two or more microstrip line resonators with one end opened and one end shorted are arranged in antiparallel and coupled to each other. The digital bandpass filter is characterized in that the high temperature superconducting microstrip line is irradiated with light to change the unloaded Q.

Further, the amplitude modulator of the present invention uses a high temperature superconductor having a length of ½ wavelength provided on a dielectric substrate,
In an interdigital bandpass filter configured by arranging and coupling two or more microstrip line resonators with both ends opened in parallel, the high temperature superconducting microstrip line is irradiated with light to change the unloaded Q. It is characterized in that it has a structure.

[0008]

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

FIG. 1 is a top view of an embodiment of the present invention.
FIG. 2 is a vertical sectional view.

The amplitude modulator of this embodiment uses an interdigital bandpass filter, and one side is short-circuited and the other side is open on the dielectric substrate 6 by the high temperature superconducting microstrip line 1. (Open), length 1
The quarter-wavelength resonators are arranged in antiparallel.

The first-stage resonator is soldered to the connector 4 and connected to an external circuit. Further, the case 2 is provided with a vacuum exhaust port 3 for preventing dew condensation inside the case.

Further, the case portion on the microstrip line resonator is provided with a light irradiation port 5 so that each resonator can be changed from a superconducting state to a normal conducting state. A cooling plate 7 is attached to the bottom surface of the case to control the temperature of the entire filter.

Although the embodiment of the present invention has been described above, the length of the microstrip line resonator is reduced to 1/2.
It is also possible to use an interdigital band-pass filter that is configured by opening both ends as a wavelength and arranging and coupling two or more resonators in parallel.

[0014]

In the interdigital bandpass filter having the high temperature superconducting microstrip line resonator having the above-mentioned structure, the insertion loss of the filter can be reduced by using the high temperature superconductor.

Further, it is possible to control the no-load Q by irradiating the superconductor with light and making a transition from the superconducting state to the normal conducting state at a high speed.

Further, by increasing the number of stages of the filter and changing the combination of light irradiation, it can be used as a variable amplitude modulator having the function of the filter.

[Brief description of drawings]

FIG. 1 is a top view of an embodiment of the present invention.

FIG. 2 is a vertical sectional view of an embodiment of the present invention.

[Explanation of symbols]

 1 High temperature superconducting microstrip line 2 Case 3 Vacuum exhaust port 4 Connector 5 Light irradiation port 6 Dielectric substrate 7 Cooling plate

Claims (2)

[Claims] 1. A microstrip line resonator having one end opened and one end shorted, which is made of a high-temperature superconductor having a length of ¼ wavelength provided on a dielectric substrate, is arranged in antiparallel with each other and coupled. In the interdigital bandpass filter thus configured, an amplitude modulator having a structure in which the high temperature superconducting microstrip line is irradiated with light to change the unloaded Q. 2. A high-temperature superconductor having a length of ½ wavelength provided on a dielectric substrate is used, and two or more microstrip line resonators whose both ends are open are arranged in parallel and coupled to each other. In the interdigital bandpass filter, an amplitude modulator having a structure in which the high temperature superconducting microstrip line is irradiated with light to change the unloaded Q.