A Low-Profile Broadband Circularly Polarized Microstrip Antenna With Wide Beamwidth

A low-profile broadband circularly polarized (CP) microstrip antenna with a wide beamwidth is proposed for a global navigation satellite system. Four claw-shaped parasitic branches are placed on the corners of the ground to widen the impedance bandwidth (IBW) and half-power beamwidth (HPBW) simultaneously. Several slots are etched on the radiation patch to obtain impedance matching. The proposed antenna is fabricated and measured. The experimental results show that the IBW for VSWR ≤ 2 is 72.5% from 1.02 to 2.18 GHz, and the 3 dB axial-ratio bandwidth is 54% from 1.15 to 2 GHz. The HPBW is beyond 100° overall CP bandwidth. Its dimensions are 70 mm × 70 mm × 12 mm, (0.35 × 0.35 × 0.06) λ
₀
³
, where λ
₀
is the wavelength of the center frequency.