Investigations on the Non-planar Log-periodic Antenna, having Tilted Dipoles

Abstract

This paper presents theoretical and experimental investigations on the non-planar log-periodic dipole antenna, whose upper and lower halves contain dipoles, inclined by angles α1 and α2 respectively. Using the fact that a tilted dipole is capable of receiving horizontally as well as vertically polarized signals, it is mathematically shown that the utility of the log-periodic dipole antenna (LPDA) can be increased by tilting the constituent dipoles. Using the linear antenna array theory, the expressions for the far field radiation patterns, power gain and aperture, are derived. Calculations were made to predict the effect of Ψ (angle between the two halves of the LPDA) and the tilt angles (α1, and β2) of the dipoles on the radiation pattern, power gain and aperture of the non-planar log-periodic dipole antenna. Comparison is made between the theoretical and experimental results. It is concluded that both the results agree reasonably.