SOLID STATE MICROWAVE POWER SOURCE FOR USE IN AN ELECTRODELESS LIGHT SOURCE

摘要

SOLID STATE MICROWAVE POWER SOURCE FOR USE IN AN ELECTRODELESS LIGHT SOURCE A solid state microwave power source for providing microwave power to excite an electrodeless lamp is designed so as to provide an acceptable impedance matching characteristic during lamp warm-up when the lamp impedance is high and changing with temperature to provide sufficient power to the lamp during the running state when the lamp impedance is matched to the source. The microwave power source includes a dc power source providing power at variable levels, a microwave oscillator receiving the dc power to produce a microwave signal, and a microwave power amplifier. The oscillator has a transistor in a common base configuration, a microstrip capacitive feedback element to sustain oscillations, and an output impedance matching arrangement formed from microstrip. The microwave signal is amplified in the solid state power amplifier having a power transistor in a common base configuration. An impedance matching section between the amplifier and the input of a termination fixture for the lamp includes a length of transmission line which transforms the input impedance of the fixture to a level at the collector of the power transistor in the amplifier so as to maximize the power delivered to the lamp at reduced power levels while maintaining the collector voltage within a safe limit.