Energy Recovery from Microstrip Passive Circuits

In this paper, the energy recovery in microstrip passive circuits from the power losses into heat is studied. For this purpose, a thermoelectric 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 the microstrip circuit is proposed, and design guidelines in order to optimize the recovered power keeping a good isolation between the RF signal and the TEG system are provided. As will be shown, under moderate applied signal powers of just 1–5 W, the levels of recovered power in microstrip passive circuits can be notable. As a demonstrator circuit, an integration device formed by an embedded microstrip bandpass filter for WiMAX applications 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 3.48 GHz, a recovered power of around 250 μW has been continuously supplied to the electrical load. Several aspects, such as efficiency and future improvements, are also discussed.This work was supported by the Euripides European Project MIDIMU-HD

Average Power Handling Capability of Microstrip Passive Circuits Considering Metal Housing and Environment Conditions

In this paper, the average power handling capability (APHC) of microstrip passive circuits considering the metal housing and environment conditions is investigated in detail. A systematic method is proposed for the computation of the APHC of microstrip circuits in open and enclosed metal housing configurations, typically used in microwave components. The method also yields an estimate of the maximum temperature in a microstrip circuit for a given input power. Closed-form equations accounting for external conditions, such as convection or radiation heat transfer are given to evaluate the APHC. For validation, two microstrip bandstop filters centered at 10 GHz are analyzed following the proposed model, and the results are compared with those simulated showing a good agreement. In addition, both circuits are fabricated and characterized. Thermal profile measurements are provided, confirming the predicted results. The effect of the topology layout and the electromagnetic performance on the APHC are also discussed.This work was supported by the Euripides European Project MIDIMU-HD