A new design for CPW-fed broadband circularly polarized square slot antenna

In this paper, we propose a new antenna design of square slot antenna with broadband circular-polarization operations. By feeding an asymmetric T-shaped co-planar waveguide (CPW) and a grounded metal strip in the slot, two CP bands can be excited at the adjacent bands near the first resonant band of the square slot. By further embedding an L-shaped grounded metal strip, two CP bands can be combined to form a wide CP bandwidth. Finally, the impedance match of the wide CP band can be obtained by slitting the asymmetric T-shaped CPW. The proposed CP slot antenna can achieve a 3-dB axial bandwidth (CPBW) of 50%, which is completely enclosed by the VSWR ≤ 2 impedance band.