A Single-Layer Wideband Differentially-Fed Dual-Polarized Filtenna With Low Cross-Polarization

Abstract

In this paper, a single-layer differentially-Fed dual-polarized filtenna (DFDPF) with low cross-polarization is developed. The developed DFDPF consists of four shorted driven patches and four triangular parasitic patches. First, each single-feed driven patch resonates at its TM₁₀ mode (corresponding to the antiphase TM₂₀ mode of the two differentially-fed patches). Incorporating shorting pins on the driven patches leads to a lower radiation null. Then, the parasitic patches are embedded into the gap between the driven patches to introduce an extra in-band resonance operating in its TM_1/2,1/2 mode, along with an upper radiation null, while the footprint remains unenlarged. This improves operating bandwidth and roll-off rate on the upper passband edge. Finally, a pair of symbiotic open-ended l-shaped stubs are integrated into each driven patch to further enhance the suppression level of the upper stopband. The developed DFDPF was prototyped and measured for experimental verification. Experimental measurements validate the feasibility of the simulation results, demonstrating a wide –10 dB fractional impedance bandwidth of 19.5% and a peak realized gain of 6.6 dBi. In addition, the cross-polarization level is lower than –40 dB.