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Design of a Wideband Circularly Polarized Strip-Helical Antenna With a Parasitic Patch
oleh: Xihui Tang, Yejun He, Botao Feng
Format: | Article |
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Diterbitkan: | IEEE 2016-01-01 |
Deskripsi
A wideband strip-helical antenna with a parasitic circular patch for circular polarization is designed in this paper. A strip-helix with 2.5 turns and a pitch angle of 5° is placed over a ground plane and coaxial probe-fed by a 50-Ω SMA connector. A parasitic patch is electromagnetic-coupled to the open end of the strip-helix with an extremely small distance. By combining the strip-helix with the parasitic patch, two nearby circularly polarized (CP) resonances are produced and a wide axial ratio (AR) bandwidth is obtained. The strip-helix can excite a CP resonance in axial mode, while the parasitic patch can generate another nearby one in fundamental mode. Radiation characteristics of the proposed design, including current distributions, reflection coefficient (S<sub>11</sub>), AR, and radiation patterns, are studied. Measured results shows that the proposed antenna has an impedance bandwidth (S1<sub>1</sub> ≤-10 dB) of 53%, an AR bandwidth (AR 3 dB) of 44%, and a peak gain of 9.4 dBi in its volume of 0.43λ<sub>0</sub>× 0.43<sub>λ0</sub>× 0.25<sub>λ0</sub>, where λ<sub>0</sub> is the wavelength in free space at the center operation frequency.