Wideband Omnidirectional Coplanar Waveguide-Fed Coaxial Dipole Antenna for VHF/UHF Communication Bands with Improved XPD

In this study, a blended coplanar waveguide-fed (BCPWF) coaxial dipole antenna with improved cross-polarization discrimination (XPD) is proposed. The proposed antenna composes of a BCWF, a metal cone and two stacked tubular metal cylinders. By blending CPWF, the effects of the current flowing through the top surface of CPWF can be minimized. This results in low XPD and wideband omnidirectional characteristics. The effects of blend radius and thickness of CPWF on bandwidth and XPD are investigated. Besides, ferrite material is utilized in the connector side to eliminate leakage currents at low frequencies. The effects of the ferrite material on the radiation pattern and VSWR are demonstrated for long cable applications. The proposed antenna operates 99-1202 MHz (VSWR <2.15; 169.8%) and has 0.48$\lambda$× 0.04$\lambda$ transverse dimensions. The peak gain of the proposed antenna is 6 dBi. The azimuth (H-plane) gain ranges from -1 dBi to 1.5 dBi for Airband (108-137 MHz) and Mode-S/ADB(800-1100 MHz) communication bands. Due to its wideband, omnidirectional, easy manufacturing, and low-cost properties, the proposed antenna can be used in high-tower, vehicle, shipboard, and air traffic control platforms in the VHF/UHF band.