A compact dual-polarized patch antenna using metamaterial-line based feeding network

A compact broadband dual-polarized patch antenna operating from 1.71 to 2.69 GHz for multi-functional services is presented. It has the total size of 100×100×22 mm3 (0.74λ0×0.74λ0×0.16λ0). Four fork-shaped probes are used to feed a square patch antenna to enhance the impedance bandwidth. A pair of broadband 180°-baluns designed using metamaterial transmission lines (MM TLs) is used in the feeding network to deliver two signals with equal power and 180° phase difference over a broad bandwidth. With the use of the baluns, the dual-polarized antenna can achieve a compact size, good isolation between two ports and low cross-polarization. The antenna is studied and designed using computer simulation. The simulated results shows that the proposed antenna has an impedance bandwidth of 48% (S11≤-10 dB) within the entire operating frequency band, and an isolation over 38 dB. The cross-polarization levels in both the E- and H-planes are less than -30 dB within the main lobe of the radiation patterns.