A new broadband cross-dipole CP antenna with modified square-cavity reflector

Abstract

ABSTRACTA new broadband cross-dipole CP antenna with modified square-cavity reflector is proposed in this work. The cross-dipole CP antenna is composed of four rotated L-shaped patches, a pair of vacant-quarter feeding loops as sequential-phase feeding network, two modified trapezoid-microstrip lines as impedance tuner, and a square-cavity reflector with four parasitic strips. Different from the traditional vacant-quarter rings, the modified vacant-quarter loops with trapezoid-microstrip lines are utilized to increase the impedance bandwidth (IBW) and provide 90° phase difference. First, the rotated L-shaped patches are used to obtain wide CP operation. Second, a square-cavity reflector is utilized for enhancing the radiation gains. Moreover, four parasitic strips are inserted into the reflector to increase the CP bandwidth. Therefore, multiple CP resonant points could be stimulated simultaneously by fully utilizing these elements, resulting in a wide CP performance. Finally, the proposed cross-dipole CP antenna has a wider −10 dB IBW of 100% (1.0–3.0, 2.0 GHz), broader 3-dB ARBW of 71.2% (1.25–2.65, 1.95 GHz), and a higher radiation gain, which can cover the WiBro (2.3–2.39 GHz) and GPS (L1 1.575 GHz) bands.