Design and Experimental Verification of a Compact Gaussian Beam Source for Parallel-Plate Waveguide Tests

We present a compact and efficient electromagnetic source able to generate a 2-D Gaussian beam in a parallel-plate waveguide. The parallel-plate waveguide is a typical guiding structure used to experimentally test in a laboratory the electromagnetic behavior of a device under test in terms of propagation, transmission, and reflection. The most common launcher for this waveguide is a quarter-wavelength monopole, which generates a cylindrical wave. However, in order to approximate the cylindrical wave to a plane-wave impinging on the device under test, this launcher needs electrically large setups. The proposed solution makes use of a metallic bidimensional parabolic reflector, which is able to transform the cylindrical wave radiated by the conventional launcher into a plane wave with the Gaussian amplitude distribution. We demonstrate that this setup can dramatically reduce the dimensions of a conventional launcher for a given directivity (i.e., planarity of the generated phase fronts). The optimum design and the experimental verification of the proposed compact launcher are presented.