A Wideband Circularly Polarized Tightly Coupled Array

Tightly coupled arrays (TCAs) have received considerable interests recently. Although various TCAs have been reported, they are generally limited to single or dual linear polarizations. Considering the importance of circularly polarization in various wireless systems, it is meaningful to design a circularly polarized (CP) TCA with a simple configuration. This communication presents a CP tightly coupled crossed dipole array (CP-TCCDA) with intrinsic CP feeding structure, which achieves wide overlapped impedance bandwidth and axial ratio (AR) bandwidth. An analysis is given to explain the principles of AR bandwidth improvement and is validated by the comparison of radiated E-fields between a CP-TCCDA and a conventional CP crossed dipole array. To verify the design concept, a 4 × 4 CP-TCCDA with elaborate feeding network is fabricated and measured. The measured results confirm that the proposed array achieves VSWR <; 3 bandwidth from 2.06 to 6.46 GHz (3.14:1) and 3 dB AR bandwidth from 2.35 to 5.6 GHz (2.38:1), which are much wider than the bandwidth of an isolated element and a conventional array using the same element.