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A broadband omnidirectional circularly polarized antenna

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Original languageEnglish
Article number6401161
Pages (from-to)2363-2370
Number of pages8
JournalIEEE Transactions on Antennas and Propagation
Issue number5
Publication statusPublished - 2013
Publication typeA1 Journal article-refereed


A broadband circularly polarized (CP) antenna is developed with an omnidirectional radiation pattern in the horizontal plane. Four broadband CP rectangular loop elements are employed for broadband omnidirectional CP radiation. The four rectangular loop elements are first printed on a flexible thin dielectric substrate and then rolled into a hollow cylinder. A conducting cylinder is introduced inside the hollow cylinder for achieving desired omnidirectional CP performance. A feeding network consisting of four broadband baluns and an impedance matching circuit is designed to feed the four rectangular loop elements. The omnidirectional CP antenna has a circular cross section with diameter of 0.38 λ0. Experimental results show that the omnidirectional CP antenna has bandwidths of 41% (1.65-2.5 GHz) for axial ratio <3 dB and 45% (1.58-2.5 GHz) for return loss 10 dB. The gain variation in the omnidirectional plane is less than 1 dB for the frequency range from 1.65 to 2.5 GHz. Good agreement is obtained between simulated and measured results.


  • Broadband antenna, circularly polarized (CP) antenna, mobile communications, omnidirectional antenna