Microwave power sources for industrial, scientific and medical applications

The industrial, scientific and medical (ISM) sector has been a growth area in recent years for applications of microwave engineering. These applications include various forms of heating and more controversial uses that exploit so-called 'non-thermal' effects of microwave exposure on biological and chemical samples. Given the non-thermal nature of these effects, the microwave power source may be adequate in pulsed, rather than continuous form. This paper will not attempt to address the questions surrounding the provenance of such effects but will discuss the challenges presented to the microwave circuit designer in delivering substantial amounts of microwave power, both continuous and pulsed, to targets that vary in size and microwave impedance properties. ISM applications may represent a large new market for radio frequency power amplifier (RFPA) products that may utilize alternative technologies and design approaches over those that have evolved for the conventional microwave applications such as telecommunications and radar.This article is part of the discussion meeting issue 'Microwave science in sustainability'.