A single-fed circularly polarized using water substrate patch antenna with small size low-profile and broadband

A single-feed circularly polarized (CP) patch antenna, characterized by small-size, low-profile and broadband, is proposed for UHF band applications (389MHz-610MHz). Its substrate, made up of water and rogers4003a, will greatly reduce the value of Q, so it can achieve wider bandwidth. The radiation structure consists of four planar spirals, a cross shaped microstrip line, and a T-shaped dipole The final prototype of the antenna, with an overall size of 200 mm× 200 mm× 1.732 mm (0.25 λ
0
×0.25 λ
0
×0.002 λ
0
at 389 MHz) is simulated. The −10 dB bandwidth of the antenna is closed to 44%, and a 3 dB axial ratio (AR) bandwidth of 19%, the gain of this antenna can achieve to −1.5dB.