Cavity Backed Cross Dipole Antenna With Wide Axial Ratio Beamwidth and High Efficiency

Abstract

This paper presents the design and realization of broadband and wide-beam right hand circularly polarized (RHCP) cross dipole antenna. The crossed dipole is backed by a conical shaped cavity to achieve improved axial ratio beam-width over a wide frequency band with enhanced gain. The design incorporates a conventional feeding technique using a coaxial probe. A sleeve is designed which is soldered with the cable to ensure strength for the cable. The fabricated prototype of the proposed antenna has an overall size of $0.87 \lambda \mathrm{X} 0.87 \lambda \mathrm{X} 0.38\lambda$ ($\lambda$ is the free-space wavelength at the lowest CP operating frequency). The obtained impedance bandwidth (RL >15dB) is 18% (2-2.4GHz) and axial ratio bandwidth (AR <3dB) is 9%. The axial ratio (AR <3dB) beam-width achieved overall phi planes is 120° for 5.5% bandwidth. Efficiency achieved is above 90% for complete bandwidth.