UWB UHF Dual-Polarized Dipole Antenna with Low-Profile Microstrip Balun

We present design and implementation results of a UHF (<tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$600-900 \text{MHz}$</tex>) antenna array for a high-power radar ice sounder followed by an improved array design concept. Results for a 64-element airborne array and a 16-element ground-based array are reported. Each antenna element consists of dualpolarized microstrip dipoles and aperture-coupled microstrip baluns that are soldered perpendicular to the dipole. Third order lumped-element impedance matching networks are used to increase the bandwidth. The operational bandwidth of the airborne array is limited to <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$675-725 \text{MHz}$</tex>, due in part to impedance mismatches from balun design, non-ideal element and ground plane separation, and mutual coupling. To address the electrical mismatch and integration challenges of the initial implementation, we present a revised antenna design with a nearplanar microstrip balun network. The total height of the antenna is reduced by <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\sim 57 \%$</tex>. Full-wave simulations show an improved return loss at the higher end of the bandwidth, and an increase in average nadir gain by <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\sim 1 ~\text{dB}$</tex> for both airborne and ground-based configurations.