Design of a Miniatured, Electromagnetic Quasi-Yagi Antenna with Circularly Polarized Characteristics

Abstract

A novel low-profile circularly polarized (CP) quasi-Yagi antenna with a wide 3-dB axial ratio (AR) bandwidth is proposed, which generates the endfire beam by combining magnetic microstrip cavity and folded electric dipoles with a 90∘ phase difference. The proposed antenna includes two shorting pins, which are employed to attain wider impedance bandwidth. Then, a phase delay line is added to connects two pairs of folded dipoles and a magnetic microstrip cavity to realize righthanded circularly polarized (RHCP). After optimization, a prototype with an overall size of 1.17×0.91× 0.0387λ30 is designed. Simulated results demonstrate that the final model has 18.1% (5.01-6.01 GHz) 3-dB AR bandwidth and −10dB impedance bandwidth of 5.2%(5.67−5.97GHz), respectively. In addition, experimental results demonstrate that the designed antenna is very applicable to the RFID system.