A Broadband Dual-Element Folded Dipole Antenna With a Reflector

A wideband dual-element planar folded dipole antenna is proposed in this letter. It is composed of a pair of asymmetric coplanar strip folded dipoles. The dual-element folded dipole antenna is fed by a microstrip feedline. With suitable design of the asymmetric coplanar strip folded dipole and the microstrip feedline, a 10-dB return-loss operating bandwidth of 107% (1.23 ~ 4.07 GHz) is achieved. By adding a metal plate, a wideband unidirectional antenna can be obtained with a measured impedance bandwidth of 113% (1.15 ~ 4.07 GHz) with better than 10 dB return loss. Its fabricated prototype is also measured with stable unidirectional radiation patterns in working band 1.13 ~ 3.3 GHz with a gain in + z-direction higher than 8.2 dBi and a front-to-back ratio better than 11.5 dB.