A Broadband Low-Profile Multiple Folded Loop Antenna

A low-profile base station antenna based on artificial magnetic conductor (AMC) is proposed in this paper. The base station antenna is composed of a pair of multiple folded loop antennas, a coaxial balun, and a wideband AMC reflector. The radiator of the antenna is composed of two layers of loop metallic patches on the upper and lower layers of the substrate, and the reflector is composed of a metallic floor and an AMC. The coaxial balun is used as the excitation of the loop antenna, which has a wide impedance bandwidth of 37.45% (2.3-3.36 GHz). The impedance bandwidth of the AMC reflector is 40.71% (2.23-3.37 GHz), which is basically consistent with the bandwidth of the loop antenna. Compared with the antenna without AMC, its height changes from 31 mm to 19.5 mm. In the whole operating band, the antenna has a beam coverage of 80° in the H planes and V planes, an impedance bandwidth of 2.12-3.5 GHz (49.11%), a cross-polarization discrimination of more than 20 dB, and a gain of up to 7.4 dBi.