A homodyne Doppler radar module is designed and fabricated in an X-band waveguide where a Gunn diode oscillator and a point contact mixer are installed and a pyramidal horn antenna is connected.
Doppler shifted signal is amplified and its frequency is counted to display the target speed in KPH (kilometer per hour).
The Gunn diode oscillator oscillates in the frequency band from 7.5GHz to 11.8GHz (which corresponds to X-band) and gives RF power about 100mW at 10.525GHz.
The supporting post for the Gunn diode in the waveguide is located at the distance of about half wavelength from the waveguide short, which is explained theoretically from the equivalent circuit description and is verified experimentally.
A rotating circular cylinder having periodically corrugated surface is used as a target in the laboratory.
The noisy detected signal is amplified and its SNR is improved by PLL and frequency duplication circuit.
