Multimode Horn with Spherical Wavefront for Constant Beamwidth

This paper presents a design method for a wideband multimode primary horn by controlling the wavefront on the aperture. This approach minimizes frequency-dependent variations in gain and beamwidth through curved taper optimization. As a design example, we present a spline-profile horn antenna optimized over a frequency range of 9-16 GHz (fractional bandwidth 56 %), achieving rotationally symmetrical radiation patterns with minimal variations in beamwidth and gain.