Recent Progress on Design Method of Microwave Power Amplifier and Applications for Microwave Heating

Abstract

Recently, GaN devices are often adopted in microwave power amplifiers to improve the performances. And many new design methods of microwave power amplifier were proposed. As a result, a highefficiency and super compact microwave signal source has become easily available. It opens up the way for new microwave heating systems. In this paper, the recent progress on design methods of microwave power amplifier and the applications for microwave heating are described. In the first, a device model of GaN transistor is explained. An equivalent thermal model is introduced into the electrical non-linear equivalent device model. In the second, an active load-pull (ALP) measurement system to design a highefficiency power amplifier is explained. The principle of the conventional closed-loop ALP system is explained. To avoid the risk of oscillation for the closed-loop ALP system, novel ALP systems are proposed. In the third, a microwave heating system is explained. The heating system monitors the reflection wave. Then, the frequency of the signal source and the phase difference between antennas are controlled to minimize the reflection wave. Absorption efficiency of more than 90% was obtained by the control of frequency and phase. In the last part, applications for a medical instrument is described. key words: GaN power amplifier, pulse-mode operation, active load-pull, microwave heating, frequency and phase control, medical instrument † The authors are with Ryukoku University, Otsu-shi, 520-2194 Japan.

Microwave Hyperthermia Application with Bioimplant Single Slot Coaxial Antenna Design for Mouse Breast Cancer Treatment

“…In most of the studies such as [20][21][22], important design parameters, such as the electrical characterization of the radiating antenna, reflection coefficient graphics, farfield radiation, SAR values on the tissue and other primary details that concern the engineers who will make the design, are not given sufficiently. In many studies showing details about the engineering aspects, publications are mostly limited to theoretical or simulation, antenna fabrication or measurements for application are not given [23][24][25][26][27] or the proposed designs are costly, far from being compact or production techniques of them are not suitable for mass production [25,26,[28][29][30]. In this study, different from the others, all details concerning electrical and electronic engineering, such as theoretical background, simulation, fabrication, and measurements related to the microwave heating and hyperthermia are presented.…”