| Summary: | 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.
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