A Dual Linear Polarization Highly Isolated Crossed Dipole Antenna for MPAR Application

The design of a dual-polarization antenna with high isolation between ports has always been a challenge in the antenna community. To overcome this issue, a pair of printed collocated bent dipoles with a unique excitation method, is introduced in this letter. A balun and parallel transmission line are concurrently designed for multifunction phased array radar in the frequency bandwidth of 2.7-3 GHz. To maximize the polarization purity of the antenna and eliminate the parasitic radiation of the balun, the radiating element is isolated from the balun by a set of ground planes. A better than 10-dB return loss and a measured port-to-port isolation of 52 dB over the whole bandwidth are achieved. The cross-polarization pattern remains 40 dB below the copolarization peak in the principal planes. Having a compact geometry, the proposed antenna can readily be extended to form an array.