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

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- $\Omega $ 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 circular polarization (CP) bandwidths, which utilize a complementary X-shaped stub and displace one arm of it from the middle to another layer. A $1\times16$ 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 $16\times16$ planar PLWA is further constructed using the $1\times16$ PLWA. Also, it has an impedance bandwidth of 52.5% (4.5–7.7 GHz) and a CP bandwidth of 34.6% (4.5–6.38 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 wideband and wide coverage, which could be a good candidate for wireless and radar applications.