JPH0216601B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a microwave integrated circuit (abbreviated as MIC) used in a frequency converter of a microwave communication device or an SHF receiver.

Conventional configuration and its problems When constructing a frequency converter by forming a frequency mixer and a local oscillator on a MIC board, a dielectric resonator is usually used as the local oscillator. On the other hand, the frequency converter is placed inside a metal housing, but at this time, the dielectric resonator used in the local oscillator and the waveguide mode resonating inside the metal housing combine, causing the local oscillator to stop oscillating. Alternatively, this phenomenon appears as an extreme decrease in the diode current of the frequency mixer, which is thought to be due to a decrease in the oscillation output.

In order to avoid such coupling between the dielectric resonator and the waveguide mode of the metal housing, the entire local oscillator including the dielectric resonator is housed in a metal housing separate from the metal housing of the frequency converter. First, place the local oscillator and frequency mixer in one metal housing, or house only the dielectric resonator in the metal housing, and then place the local oscillator and frequency mixer in one metal housing. The conventional method was to place it inside the body.

However, with the conventional method of duplicating the metal casing,
Two types of metal casings are required, which not only complicates the configuration of the metal casing, but also makes the inner metal casing
The disadvantages are that the microwave integrated circuit structure inside the housing is subject to various layout restrictions, and the outer metal housing becomes extremely large in size.

Purpose of the Invention The purpose of the present invention is to remove the inner metal casing that surrounds only the local oscillator or the dielectric resonator, and to remove the dielectric resonator and the outer metal casing that are generated when this metal cylindrical body is removed. The objective is to provide a MIC that easily prevents coupling with the waveguide mode that resonates in the MIC.

Structure of the Invention In the present invention, a local oscillator and a frequency mixer are placed in the same metal housing, and a radio wave absorber is placed at an appropriate position within the metal housing.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of the present invention will be described based on the drawings.

1A and 1B are diagrams showing an embodiment of a microwave integrated circuit according to the present invention, in which FIG. 1A is a plan view and FIG. 1B is a sectional view. A local oscillator 4 is configured by a GaAsFET 2 and a dielectric resonator 3 arranged on a microwave integrated circuit board 1. A frequency mixer 5 is configured on the same microwave integrated circuit board 1 as the substrate on which the local oscillator 4 is configured, but the frequency mixer 5 mainly consists of three open-ended stubs 6. It consists of a signal blocking filter 7 and a mixer diode 8. Reference numeral 9 denotes a rectangular metal casing, and within the metal casing 9 a frequency converter 10 consisting of a local oscillator 4 and a frequency mixer 5 is arranged. A radio wave absorber 11 is arranged along the inner wall surface of the metal casing 9 and near the image signal blocking filter 7.

In the embodiments shown in FIGS. 1a and 1b, the waveguide mode resonating within the metal casing 9 is suppressed by the radio wave absorber 11, and moreover, the radio wave absorber 11 is placed away from the dielectric resonator 3. The resonant electromagnetic field of the dielectric internal resonator 3 is not affected by the radio wave absorber 11, and the local oscillator 4 operates normally. In other words, the oscillation power of the local oscillator 4 is normally applied to the mixer diode 8. Furthermore, since the radio wave absorber 11 is placed near the image signal blocking filter 7, the coupling between the image signal blocking filter 7 and the waveguide mode resonating within the metal casing 9 is simultaneously suppressed, and the frequency converter The conversion loss characteristics and image suppression ratio characteristics of No. 10 have the effect of eliminating the adverse effects from the metal casing 9.

Effects of the Invention As described above, according to the present invention, the coupling between the waveguide mode resonating within the metal housing and the dielectric resonator is suppressed by the radio wave absorber disposed within the metal housing, and the local oscillator is abnormal. In addition to preventing movement, the radio wave absorber placed inside the metal casing allows
The waveguide mode that resonates inside the metal housing is suppressed,
It is possible to eliminate the adverse effects of the metal casing on the conversion loss characteristics and image suppression ratio characteristics of the frequency converter. Furthermore, since the local oscillator output is efficiently applied to the mixer diode and a sufficient mixer current flows, a stable frequency conversion circuit can be constructed, the local oscillator output can be small, and local signal leakage to the RF input side is reduced.

[Brief explanation of drawings]

FIGS. 1a and 1b are a plan view and a sectional view showing a microwave integrated circuit according to an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Microwave integrated circuit board, 3... Dielectric resonator, 4... Local oscillator, 5... Frequency mixer, 6... Open termination stub, 7... Image signal blocking filter, 9... Metal casing Body, 10... Frequency converter, 11... Radio wave absorber.

Claims (1)

[Claims] 1. A local oscillator whose oscillation frequency is controlled by a dielectric resonator and a frequency mixer including an image signal blocking filter configured with an open-ended stub are formed on a microwave integrated circuit board, and the microwave integrated circuit is A microwave integrated circuit characterized in that the substrates are arranged in the same metal casing, and a radio wave absorber is arranged near the image signal blocking filter.