Multimode cavity efficiency optimization by optimum load location--experimental approach

In this paper, a novel load-matching procedure for microwave-heating applicators is presented and tested. In order to accomplish the optimization procedure, an optimization method based on the use of the Lebenverg-Marquardt technique has been specifically developed and tested on two different microwave ovens. The proposed procedure allows an efficient optimization of three-dimensional microwave applicators by means of the dielectric sample relocation as a function of its complex permittivity, size, and operating frequency. Experimental measurements of the reflection coefficient are presented and analyzed over several samples and multimode cavities. Results indicate that high power efficiencies can be obtained provided that operating frequency is not just below TM-mode cutoff frequencies for the transverse dimensions of the oven. Index Terms--Electromagnetic heating, load matching, multimode applicator, power efficiency.