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A compact wideband four‐arm spiral antenna with dual modes
Author(s) -
Chang Lei,
Chen LingLu,
Chen ZhuangZhi,
Zhang JianQiang
Publication year - 2021
Publication title -
microwave and optical technology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.304
H-Index - 76
eISSN - 1098-2760
pISSN - 0895-2477
DOI - 10.1002/mop.32724
Subject(s) - spiral antenna , optics , logarithmic spiral , physics , wideband , antenna (radio) , ground plane , helical antenna , radiation pattern , coaxial antenna , engineering , telecommunications , geometry , mathematics
Abstract A compact wideband four‐arm circularly polarized (CP) spiral antenna with both sum mode (1) and difference mode (2) is presented. The antenna is composed of a modified four‐arm equiangular spiral, a four‐arm z‐directional helix, a ring‐shaped absorber, and a ground plane. By using the modified equiangular spiral and the z‐directional helix, the impedance matching of mode 1 and mode 2 is improved, and the cross‐polarization discrimination of mode 2 is also improved in the low frequency band. The z‐directional helix is also applied to achieve a compact size of the antenna and an enhanced AR bandwidth of mode 2. A prototype of the four‐arm spiral antenna is fabricated and measured with a beamformer operating at 0.5 to 2 GHz. It is shown that both sum and difference radiation patterns are generated in the whole frequency band of 0.5 to 2 GHz. The overall size is 0.486 λ 0.5 GHz × 0.097 λ 0.5 GHz (diameter × height, λ 0.5 GHz is the free‐space wavelength at 0.5 GHz).