Analysis of the effect of finite gap width on the admittance of solid circular dipole

The authors consider a center-fed solid circular cylindrical dipole radiating in a circular waveguide terminated in infinite ground planes. Numerical results show how the input admittance depends on the dipole length, feed gap width, and waveguide radius. From the input admittances of the enclosed system, the oscillations of which exhibit a decaying almost periodic variation as the radius increases, the input admittances of dipoles radiating in free space are estimated by averaging the admittances of the bounded system over two periods for large radius-to-wordlength ratios.<>