Optical study of the EH_11 mode in a hollow circular oversized waveguide and Gaussian approximation of the far-field pattern

This paper gives the main characteristics and an optical description of the fundamental EH11 mode propagating in hollow circular oversized waveguides. The quasi-Gaussian beam radiated by this mode in the far field is derived from a recently developed optical model to calculate the Gaussian beam transmission through hollow circular oversized waveguides. A simple relation is found between optical characteristics of the EH11 mode in the waveguide and the quasi-Gaussian beam in the far field. The results agree well with previous theoretical and experimental works.