Design and Analysis of 3mm Multimode Monopulse Feed

The design and analysis of a monopulse multimode feed used in a cassegrain antenna at 3mm waveband is described in this paper. A new combination of higher modes has been given, which will result in a novel structure that is easier to fabricate and more aseismatic. A better way has been proposed to keep the modes in phase at the horn aperture. By adjusting the amplitude and phase of the modes and the length of the phase section, a good performance is achieved with low side lodes, radiation patterns in both the elevation plane and the azimuth plane are in good agreement.