A high power high efficiency integrated solid-state microwave heating structure for portable diagnostic healthcare applications

This paper presents a novel approach for designing solid-state microwave heating arrangement designed for portable and field-deployable microwave assisted health-care diagnostic application. The arrangement contains a purpose-build TM010 mode Circular microwave cavity driven by a 10W-LDMOS power transistor as microwave source. In this method, the natural impedance environment of the resonant cavity has been considered as a function of temperature, and used to present the inherent optimal loading conditions to the 10W LDMOS power transistor for achieving high-efficiency operation over the operational bandwidth of the cavity resonator. Significant reduction in the output matching network complexity using simple microstip series lines and straightforward integration into a microwave resonant cavity makes this structure suitable for portable health-care diagnostic applications. In this demonstrator, an in-built directional coupler has also been included at output stage of power amplifier to measure the RF power and to reduce the physical size of the microwave heating arrangement. Measurement results show more than 60% Power Added Efficiency, above 40dBm output power and above 20dB Gain over the targeted Bandwidth and expected temperature variation.