Study on energy recovery from substrate integrated waveguide circuits

Abstract

In this work, the energy recovery in microwave passive circuits from the power losses into heat is studied. For this purpose, a thermo-electric generator (TEG) based on the Seebeck effect principle is used, which converts part of the power dissipated into heat to DC electrical power. A solution integrating the TEG with a substrate integrated waveguide (SIW) circuit is proposed, and design guidelines in order to optimize the recovered power are provided. As will be shown, under moderate applied signal powers of just 1-5 W, the levels of recovered power in SIW passive circuits can be notable. As a demonstrator circuit, an integration device formed by an X-band SIW bandpass filter and a TEG is designed, fabricated and characterized (thermal and electrically). Different scenarios are considered, depending on frequency and thermal loads. For an applied inband CW input signal power of 2 W at 9.68 GHz, a recovered power of around 310 μW has been continuously supplied to the electrical load. Several aspects such as efficiency and future improvements are also discussed.