Kabushiki Kaisha Toshiba

Tokyo Shibaura Denki Kabushiki Kaisha

Furuno Electric Company Limited

Hideki Torizuka

Kenji Hirai

Shigekazu Hori

Tomohide Soejima

Koji Dai

Akio Funae

A microwave frequency converter for a radar receiver is provided in which a frequency of a local oscillator of the microwave frequency converter can be prevented from interfering with an oscillation frequency of a magnetron included in the radar receiver and which can receive a signal from a considerably short distance. A voltage of an RF amplifier connected to the microwave frequency converter is synchronized with an oscillation output of the magnetron. The gate and drain voltages of a FET used in the RF amplifier are simultaneously switched OFF only during times before and after the magnetron performs oscillation, thereby switching an amplification function of the FET to an attenuation function thereof to increase a switching loss of the microwave frequency converter. Thereby, an excessively large power RF signal directly input from the magnetron and an excessively large power RF signal reflected from a short distance are attenuated to prevent the microwave frequency converter from being saturated, and the frequency of the local oscillator from interfering with the oscillation frequency of the magnetron.

Microwave frequency converter

A frequency converter includes a mixer, a local oscillator connected to the mixer by a line which transmits a local oscillator signal to the mixer and a starter circuit for supplying a transient bias current to the mixer for insuring the start of the local oscillations.

Frequency converter

An FET oscillator wherein a bias circuit is connected to a drain of a field-effect transistor and a source circuit including a transmission line and a self-bias circuit is connected to a source of the transistor, so that the source is substantially open-circuited at an oscillation frequency and the field-effect transistor operates as a two-terminal (the gate and drain) element exhibiting a negative resistance, and wherein a resonant circuit is connected to the gate of the transistor. With the source circuit connected to the transistor source, the oscillator can have a high unloaded Q-value of Qo and a high externally-loaded Q-value of Q.sub.ext, whereby the oscillation frequency is stable. According to this oscillator, only a single bias circuit for the drain is required without the need of a bias circuit for the gate.

FET oscillator exhibiting negative resistance due to high impedance at

A microwave solid-state oscillator includes a casing hermetically enclosing a microwave oscillation device and a dielectric resonator electromagnetically coupled with the microwave oscillation device, an output terminal leading out an oscillation output from said casing, and a microwave terminal electromagnetically coupled to the dielectric resonator, one end of which is connected to a microwave line having a terminating admittance at the outside of the casing.

Growing community of inventors

Kawasaki, Japan

Hideki Torizuka