A broadband 180° microstrip balun is employed as a feed network for the L-probe square patch antenna. The broadband balun delivers impedance matching, equal amplitude power division, and consistent 180° (±10°) phase shifting over a wide band (∼45%). We demonstrate that the use of the 180° broadband balun affords significant H-plane cross-polarization suppression across the wide impedance bandwidth designed for L-probe patch antennas. The antenna using the 180° broadband balun exhibits a measured impedance bandwidth (SWR < 2) of 37.15%, from 1.6 to 2.33 GHz. Across our bandwidth of interest (1.7 to 2.3 GHz), the measured boresight gain ranges from 6.16 to 8.5 dBi, and the measured H-plane cross-polarization levels are consistently well suppressed (<−20 dB).