Dual-polarized L-probe patch antennas afford wide impedance bandwidth and increased channel capacity. However, due to the close proximity, the coupling between the two input ports remains an important problem. In this paper, we introduce the use of a novel 180deg broadband microstrip balun which delivers both balanced power splitting and consistent 180deg (plusmn5deg ) phase shifting over a wide band (>50%). We demonstrate that for the quadruple L-probe square patch antenna utilizing a "dual-feed" mechanism, the use of a pair of the proposed 180deg broadband baluns allowed for a wide input port isolation bandwidth (S21<-33 dB) of 46.97%, while also achieving low cross-polarization levels and stable co-polarization patterns