Numerical techniques for VHF/UHF cylinder radiators

The frequency response of a dipole with asymmetric radii fed in the sleeve via a coaxial aperture is computed. A numerical electromagnetics code (NEC4.1) wire grid model is compared with a body of revolution finite difference time domain (2.5FDTD) solid model after Fourier transformation. Directive gain patterns and source impedance show an effective approach to designing a broad range of omnidirectional TM/sub Z/ antennas for VHF/UHF spectrum.