International Symposium on Antennas and Propagation
Ultra-Wideband Circularly Polarized Spiral Antenna Using Integrated Balun
Jen-Chun Yeh, Shiou-Li Chen, Chia-Hsien Chen, Shau-Gang Mao,
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The proposed equiangular spiral antenna has been investigated theoretically and experimentally. The spiral antenna and the tapered microstrip balun printed onto one spiral arm are successfully integrated to achieve circular polarization with broad bandwidth. The measured results show 11 S < -10 dB from 3.75 to 18.6 GHz and axial ratio < 3 dB from 3 to 14.5 GHz. This antenna radiates both RHCP and LHCP waves on each side of the antenna plane with 3.5 to 7 dBic gain within the operating band. The presented antenna can be backed by an absorber-loaded cavity for some applications when unidirectional operation is required. The insignificant pulse response of the proposed antenna is validated by the measured results with high fidelity (> 0.89). The proposed spiral antenna is suitable for numerous applications, such as the high resolution and object identification radar sensor.