Microwave Quasi-Optical High Power Hybrid MESFET Grid Array Oscillator

• Main Authors: Chen Chiong Hong, 陳火冏宏
• Other Authors: Christina F. Jou
• Format: Others
• Language: en_US
• Published: 1994
• Online Access: http://ndltd.ncl.edu.tw/handle/41883626211441634228

碩士 === 國立交通大學 === 電信研究所 === 82 === Solid-state devices can not generate large power at very high frequency,it is necessary to combine many solid-state devices to obtain high power. In the thesis, the quasi-optical high power hybrid MESFET grid array oscillator is designed. The fabrication and measurement are also present. The project is based on the circuit designed by Prof. Rutledge's group in California Institute of Technology. The frequency of oscillator is determined by the period and the lead width of grid, and the substrate used. Therfore, it is necessary to study the electromagnetic field in the grid and obtain the equivalent circuit. The equivalent circuit of oscillator is simulated by Libra. When bias at Vds=3 V, Vgs=-0.9V, Fabry-Perot mirror locate at the back of grid at about 3.5mm, the oscillation frequency is measured to 4.1GHz. Because the grid require high symmetry, we sampled 50 MESFET to find 16 FET with similar quality. The duroid has a dielectric constant of 10.5, and the thickness is 100mil. The oscillator is formed by combining 16MESFET in Fabry-Perot cavity. The distance between horn and grid is 22cm. Using the spectrum analyzer, at Vds=3V, Id=12.5mA, the oscillation frequency is measured at 4.0GHz. The power received by spctrum analyzer is 7.66dBm, it is about more than 150mW. The harmonic distortion is less -35dBc. If use the monolithic technique, it will generate much more power.