Abstract
A dual-band omnidirectional circularly polarized (CP) antenna using composite right/left-handed (CRLH) transmission line (TL) with miniaturized size is presented. The antenna consists of a circular radiation patch and a circular ground connected by three copper shorting vias, on which three rectangular slits are etched. Two sets of opposite branches are arranged in sequence around the radiation patch and ground to widen the impedance bandwidth (BW). The zeroth-order resonance (ZOR) structure by CRLH-TL and meandering technology allow miniaturization of the antenna, and rectangular slits realize wide low axial-ratio (AR) performance in the azimuth plane. The dual-band antenna is fabricated and measured. The overall size of the antenna prototype is only 0.208λ L × 0.208λ L × 0.026λ L , where λ L is the free-space wavelength at the center working frequency of the low band. The BW in the lower band has a range of 2.39 GHz to 2.42 GHz, equivalent to 1.25%, and that of the upper band has a range of 5.6 GHz to 6.0 GHz, equivalent to 6.90%. The AR bandwidth (ARBW) has ranges of 1.9 GHz to 2.6 GHz at 2.4 GHz, approximately 29.2%, and 4.6 GHz to 7.3 GHz at 5.8 GHz, equivalent to 46.6%. The overlap BW covers the two frequencies of unmanned aerial vehicle (UAV) image transmission, 2.4 GHz and 5.8 GHz in China.
Highlights
Omnidirectional circularly polarized (CP) antennas are widely used in systems with high signal requirements, such as spacecraft, television systems and remote sensing systems, because they omnidirectionally radiate CP waves in plane
Frequency bands based on the omnidirectional CP antenna, can effectively increase the practicality of the antenna and serve the image transmission unmanned aerial vehicle (UAV) operating at 2.4 GHz and 5.8 GHz
THE REALIZATION OF DUAL-BAND AND WIDE AR bandwidth (ARBW) The antenna achieves omnidirectional CP at dual-band of 2.4 GHz and 5.8 GHz, the upper of which is controlled by zeroth-order resonance (ZOR) and the lower is controlled by the orthogonal mode produced by the arc branches
Summary
Omnidirectional CP antennas are widely used in systems with high signal requirements, such as spacecraft, television systems and remote sensing systems, because they omnidirectionally radiate CP waves in plane. B. THE REALIZATION OF DUAL-BAND AND WIDE ARBW The antenna achieves omnidirectional CP at dual-band of 2.4 GHz and 5.8 GHz, the upper of which is controlled by ZOR and the lower is controlled by the orthogonal mode produced by the arc branches. The characteristic of CP and the control of dual bands are mainly realized by adjusting arc branches and resonant cavity composed of the radiation patch, ground and shorting vias. This may occur because increasing R2 results in the reduction of radiation patch area, which reduces the inductance of the coupling or series. Simulated and measured (a) S11 and (b) AR of the fabricated prototype
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
