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Application of a Parasitic Loop on Loosely Wound Short-Arm Spiral Antennas
Yasuhiro KAZAMA Nagayoshi MORITA Shinobu TOKUMARU
IEICE TRANSACTIONS on Communications
Publication Date: 1998/11/25
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Antennas and Propagation
loosely wound short-arm two-wire archimedean spiral antenna, axial ratio, power gain, current distribution,
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Loosely wound short-arm two-wire Archimedean spiral antennas are investigated. It is shown that good circularly polarized waves with axial ratio less than 2 dB are obtained when the outer circumference C of the spiral antenna is in the range of about 1. 3λ < C < 1. 5λ, where λ is the free-space wavelength. To improve the antenna characteristics further, spiral antennas combined with a parasitic loop are examined. It is clarified that the parasitic loop greatly contributes to the improvement of the axial ratio and power gain.