Broadband Tri-Polarized Antenna for Ku-Band Radar Seeker

This paper presents a tri-polarized antenna operating at a central frequency of 16 GHz. The antenna is composed of a dual-layer microstrip patch antenna and a monopole antenna, with a size of 12.2mm × 12.2mm × 6.54mm and an impedance bandwidth of 14.42 GHz to 17.44 GHz (19%) with VSWR<2. Due to the small absolute size of the antenna at high frequencies and to ensure structural stability, the radiating elements of the antenna are entirely embedded within the dielectric substrate. By exciting three ports, the antenna generates three mutually orthogonal polarizations (along the x-axis, y-axis, and z-axis), enabling significant gain at low elevation angles and achieving ±90° beam coverage. At 16 GHz, the antenna exhibits gains greater than 7 dB for x-axis and y-axis polarizations, while the maximum gain for the z-axis polarization is 1.7 dB.