Compact dual‐polarized dipole antenna with high isolation using hybrid balun circuit

In this article, a crossed dipole antenna with compact size (43 × 43 mm2) and high isolation (42 dB) is proposed using a hybrid balun circuit. The hybrid balun consists of a tapered balun and a Marchand balun. The tapered balun transforms the microstrip line into the parallel feeding lines for one pair of dipoles, and the Marchand balun transforms the stripline transmission line into a couple of out-of-phase feeding lines for the crossed pair of dipoles. Due to the low coupling between two different baluns, a high isolation of the antenna can be achieved when the crossed dipole antenna is cascaded with the hybrid balun. Moreover, these two baluns can improve impedance matching and therefore further miniaturize the size of the crossed dipole antenna. The impedance matching of two baluns can be controlled and adjusted independently. As a result, the proposed dual-polarized antenna has the bandwidth of 1.7 to 2.8 GHz for S11 < −15 dB with compact size and high isolation. The proposed antenna with the hybrid balun circuit are fabricated, and the simulated and measured results meet well.