JPH01191503A - Microwave output monitor circuit - Google Patents

Abstract

PURPOSE:To facilitate the mount and to monitor microwave output power properly by providing a directional coupler connecting to a monitor line having a length of a half the wavelength of an outputted miorowave or below by a resistor. CONSTITUTION:A directional coupler 19 is provided, which connects to a monitor line 12 having a length of a half the wavelength of an outputted microwave or below by at least a resistor 16. Thus, the chip resistor 16 is connected to decrease the length of line, that is, the coupling with a leaked radio wave is decreased in a case 14 is decreased negligibly, and when the length of the monitor line 12 is especially long, the number of resistors 16 is increased to decrease the length of each line more than lambda/2. The output as the monitor power is attenuated by the connection of the resistor 16 and a required monitor output is obtained by increasing the coupling coefficient of the directional coupler 19. Thus, the cost reduction and ease of mount are attained and the accurate microwave output is monitored.

Description

[Detailed Description of the Invention] [Summary] This invention relates to a microwave output monitor circuit equipped with a directional coupler for monitoring the microwave output of a microwave band transmitter, which has a simple configuration and is easy to install. The purpose of the present invention is to provide a microwave output monitor circuit that is inexpensive and can accurately monitor microwave output power, and has a line length that is less than 1/2 of the wavelength of the output microwave. The microwave output monitor circuit includes a directional coupler formed by connecting lines using at least one resistor.

[Industrial application field]

The present invention relates to a microwave output monitor circuit including a directional coupler for monitoring the microwave output of a microwave band transmitting device.

[Conventional technology]

A directional coupler is usually added to the output end of a microwave band high power amplifier (which is made of a compound semiconductor such as GaAs) for monitoring its output power. This directional coupler is often formed of a microstrip line, and an example of the directional coupler installed inside the housing is shown in the plan view of FIG. 4, in which 11 is an output line, 12 is a monitor line, 13 is a dummy resistor of, for example, 50Ω, and the monitor line 12 within the range surrounded by the broken line in the figure
The length of is set to λ/4 (λ is the wavelength of the output microwave).

Using this directional coupler, output line 11 and monitor line 1
Adjust the interval between 20 and 20 to 20
The microwave output is monitored by inputting it to a monitor device as a monitor output with a drop of ~30 decibels.

FIG. 5 is a cross-sectional view taken along the line V-V in FIG.
is a copper strip line with a thickness of 30 μm. The directional coupler shown in FIG. 4 is a coupler with good characteristics that exhibits flat frequency characteristics over a certain frequency band.

[Problem that the invention seeks to solve]

The directional coupler constructed from the microstrip line described above provides good characteristics when it is installed as a single unit in a closed space and separately from the amplifier.

Even in this case, a monitor system with a complicated configuration must be separately provided, and the directional couplers must be adjusted one by one, which requires a considerable amount of time. When a directional coupler is provided in the same housing as an amplifier circuit, there are problems such as variations in monitor output power and poor flatness of frequency characteristics. This is because the power coupled by the monitor line 12 with the leakage radio waves inside the housing becomes so large that it cannot be ignored compared to the coupled power in the portion of the directional coupler surrounded by the broken line in FIG. The frequency characteristics of leakage radio waves are complex in various ways, and this affects the originally flat frequency characteristics of the directional coupler, causing problems in monitoring the microwave output.

Therefore, the present invention has a simple configuration and is easy to install.
It is an object of the present invention to provide a microwave output monitor circuit that is inexpensive and can accurately monitor microwave output power.

[Means for solving problems]

The above problem is solved by a directional coupler formed by connecting a monitor line with a line length less than 1/2 of the wavelength of the output microwave using at least one resistor. This is accomplished by a microwave output monitor circuit.

[Effect]

In the present invention, a resistor is connected to the output line of a directional coupler formed by a strip line, and the length of the line is set to λ/
It is designed not to exceed 2.

〔Example〕

Hereinafter, the present invention will be specifically explained with reference to an illustrated embodiment.

Referring again to FIG. 4, in the directional coupler shown in the same figure, the longer the length of the monitor line 12, the greater the coupling with the leakage radio waves inside the housing, and it becomes particularly large when the length exceeds λ/2. It was confirmed through experiments that this is true. However,
Even if it is desired to shorten the monitor line 12, there is a limit due to the positional relationship between the amplifier circuits formed in the same housing and the monitor output ends.

Therefore, in the present invention, by connecting a resistor (chip resistor) 16 as shown in FIG. 2, the line is shortened, that is, the coupling with leakage radio waves inside the housing is made small enough to be ignored. . If the length of the monitor line 12 becomes particularly long, the length of each line is made shorter than λ/2 by increasing the number of resistors 16. The output as monitoring (monitor) power is attenuated by connecting the resistor 16, but this increases the coupling coefficient of the directional coupler (by doing so, the required monitoring output can be obtained.The monitoring output power is added to the detection diode). When the monitoring output is extracted as a DC output, the same processing as above is performed.

FIG. 1 is a plan view of an embodiment of the present invention.
is input and sent to the antenna as a microwave output via the output line 11 and the coaxial connector 18, and the output of the directional coupler 19 according to the present invention is input to a detector (not shown) as a monitoring output via the coaxial connector 18. be done. The illustrated example shows a case where two chip resistors 16 are used.

The manner in which the monitor line 12 is connected using the chip resistor 16 is shown in the cross-sectional view of FIG.
This electrode 21 is connected to the monitor line 12 by solder 22. Since the directional coupler 19 of the present invention is constructed by simply connecting the monitor line 12 with a chip resistor in this way, manufacturing costs can be reduced and installation is easy. This allows accurate monitoring of the microwave output.

〔Effect of the invention〕

As described above, according to the present invention, in response to the requirement for flat frequency characteristics in the output for monitoring microwave output power, the required flat frequency characteristics can be obtained without the need for individual adjustments. This solves the problems of the conventional example, which had large individual variations, poor frequency characteristics, and required a large amount of adjustment to obtain the desired characteristics.

[Brief explanation of the drawing]

Fig. 1 is a plan view of an embodiment of the present invention, Fig. 2 is a plan view showing the principle of the invention, Fig. 3 is a sectional view of a chip resistor connection section, Fig. 4 is a plan view of a conventional example, and Fig. 5 is a plan view showing the principle of the invention. FIG. 4 is a sectional view taken along the line V-V in FIG. 4; In the figure, 11 is an output line, 12 is a monitor line, 13 is a dummy resistor, 14 is a housing, 15 is a dielectric substrate, 16 is a chip resistor, 17 is an amplification transistor, 18 is a coaxial connector, and 19 is a directional coupler. , 20 is a resistive film, 21 is an electrode, and 22 is solder. Patent applicant: Fujitsu Ltd. Representative Patent Attorney Akigamoto Kuki, y7't! ll','LQn#1ffl 1
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Claims (1)

[Claims] A monitor line (12) having a line length less than 1/2 of the wavelength of the output microwave is connected to at least one resistor (16).
1.) A microwave output monitor circuit comprising a directional coupler connected using a directional coupler.