Broadband Dual-Polarized Planar Antennas for Radar With Printed Circuit Balun

This paper demonstrates the design and implementation of two dual-polarized ultra-wideband antennas for radar ice sounding. The first antenna operates at UHF (600-900 MHz). The second antenna operates at VHF (140-215 MHz). Each antenna element is composed of two orthogonal octagon-shaped dipoles, two inter-locked printed circuit baluns and an impedance matching network for each polarization. We built and tested one prototype antenna for each band and showed a VSWR of less than 2:1 at both polarizations over a fractional bandwidth exceeding 40 %. Our antennas display cross-polarization isolation larger than 30 dB, an E-plane 3-dB beamwidth of 69 degrees, and a gain of at least 4 dBi with a variation of +/- 1 dB across the bandwidth. We demonstrate peak power handling capabilities of 400-W and 1000-W for the UHF and VHF bands, respectively. Our design flow allows for straightforward adjustment of the antenna dimensions to meet other bandwidth constraints.