A Compact Light-Weight Gaussian-Beam Launcher for Microwave Exposure Studies

A new type of compact Iight-weight Gaussian-beam launcher for producing a focused-microwave exposure field in biological experiments is described. This launcher is identical to the structure described by the authors elsewhere, except that a simple circular waveguide aperture, instead of a corrugated pipe is used to illuminate a dielectric sphere lens with the result that a considerable weight and size reduction of the launcher is achieved. The proposed structure consists of a simple cylindrical waveguide excited with a balanced mixture of complementary modes and the diffracted field due to this waveguide aperture is made to illuminate a dielectric sphere (lens). It is shown that a near-circular Gaussian beam is then pruduced in the image space of the sphere with a high focusing factor. Design details, theoretical calculation, and experimental results concerning a practical launcher are presented. Suitability of this compact structure for diathermy applications at a frequency of 2450 MHz is mentioned.