Beam pattern of coaxial exciter for multiband mirror antennas

The far field pattern analysis by the Kirchhoff method for a quasi-omnidirectional radiator in the form of ancoaxial waveguide opened end excited with an H/sub 11/-wave is performed. The comparison of directivity characteristics for the coaxial radiator and the open ended circular waveguide both excited with H/sub 11/ waves is also carried out. The possibility of these radiators forming the far field main lobes with equal width at a certain level and for given different frequencies was shown.