The Horn Antenna as Gaussian Source in the mm-Wave Domain

Rising progress of mm-wave technology in spectroscopy, remote-sensing and its prospective application in communications requires accurate radiation beam characterization in quasi-optical systems. Gaussian approximation is a well-known practical model at optical and infrared wavelengths, and here we try to show the performance and limits of this method for the horn antenna as a classical mm-wave radiation source. This approach provides a compact and more practical analytical tool to design and optimize quasi-optical systems, compared to electromagnetic (EM) full-wave solutions. The radiation pattern (beam shape) and the phase distribution are studied analytically, both with the EM full-wave method and Gaussian approximation. Comparative results with measurements are presented to verify the analytical process and show the feasibility of the method for conventional horns.