A Compact Unidirectional Ultra-Wideband Circularly Polarized Antenna Based on Crossed Tapered Slot Radiation Elements

In this communication, a novel compact and unidirectional circularly polarized antenna based on the crossed printed tapered slot radiation elements is proposed with the ultra-wideband operation. The antenna consists of two crossed tapered slot radiation elements, a compact dual-feed network, and a dial-shaped parasitic metallic strip. The tapered slot element is applied and investigated for wideband coverage within a compact size. By using the proposed parasitic patches, an additional resonant point is formed to improve the operation bandwidth for the low band. To enhance the directivity in the low band, a dial-shaped parasitic metallic strip is loaded on the top substrate. With the proposed structure, a compact volume of 0.33λ × 0.33λ × 0.3λ is obtained, where λ is the free-space wavelength at the lowest frequency of 1.85 GHz. A prototype is fabricated and measured for validation. The overlapping bandwidth of the 10 dB impedance bandwidth and the 3 dB axial ratio bandwidth is 105.8% (1.85-6 GHz).