Tri-mode horn antenna for directive 3D-imaging

A horn antenna fed by three circular waveguide modes is presented enabling directive imaging. The feed excites the E
01
and two orthogonal H
11
modes with good mode purity within 2 GHz around the center frequency of f
c
= 25 GHz. The modes are radiated by a linear tapered horn antenna. The fundamental limits of modal beamsteering are analyzed with the focus on level gauging. Imaging enables the localization of parasitic reflectors even within the beamwidth of the fundamental H
11
pattern making it a promising candidate for next generation level radars.