Research on Circularly Polarized Leaky-Wave Antenna Based on Slotline
In this article,a circularly polarized leaky-wave antenna with beam-scanning from backward to forward is proposed based on the slotline structure.Each leaky-wave unit cell consists of a slotline and four short-ended slots loaded on the two strips.To realize the property of backward-to-forward beam scanning,the length of each short-ended slot is about half of the guided wavelength at the broadside frequency.By designing the location of the short-ended slots as well as the angle between the short-ended slot and the propagation direction of the guided wave,the circularly polarized ability is obtained.As a validation of the proposed circularly polarized leaky-wave antenna,a prototype with broadside frequency of 10 GHz is designed and fabricated.Both the simulated results and the measured results show that this antenna exhibits good properties of circular polarization and beam scanning.The measured results suggest that this antenna exhibits left-handed circular polarization in the upper-half space above the antenna plane,and scans from-27° to+25° with gain varia-tion of 7.0 to 10.9 dBic as the frequency varies from 9 GHz to 11 GHz.Symmetrically,this antenna features right-handed circular polarization in the lower-half space below the antenna plane,with beam scanning from-153° through±180° to+155°and gain variation of 8.4～12.3 dBic.Compared with the reported antennas,the proposed circularly polarized leaky-wave antenna features a simple configuration.Meanwhile,the proposed design based on the short-ended slot achieves a low transmission coefficient in the working band.
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