A Wideband Circularly Polarized Periodic Leaky-Wave Antenna Using a Novel Unit Cell With X-Shaped Slot

Abstract

A wideband circularly polarized periodic leaky-wave antenna (PLWA) using a novel unit-cell with X-shaped slot is proposed. The X-shaped slot is fed by a 50 Ω microstrip line with an X-shaped stub closely on top of it. Furthermore, an equivalent circuit of the proposed unit-cell is established and verified. Approaches are introduced to enhance the impedance and CP bandwidths, which utilize a complementary X-shaped stub and displace one arm of it from the middle to another layer. A 1 × 16 PLWA is constructed with good CP performance. The open-stopband (OSB) is suppressed by using trapezoidal arms of the slot and stub and the CP performance of diffracted field is improved by introducing a pair of extra grounds. A 16 × 16 planar PLWA is further constructed using the 1 × 16 PLWA. And it has an impedance bandwidth of 52.5% (4.5 GHz – 7.7 GHz) and a CP bandwidth of 34.6% (4.5 GHz – 6.38 GHz) in the experiment. The frequency scanning range is from -58° to 48°, while the CP coverage is from -58° to 13°. The proposed antenna features a wide band and wide coverage, which could be a good candidate for wireless and radar applications.