Two New Ultra Wideband Dual Polarized Antenna-Feeds Using Planar Log Periodic Antenna and Innovative Frequency Independent Reflectors

Abstract

Two new design algorithms of ultra wideband antenna-feeds for applications in the VHF/UHF/microwave communication systems, radio astronomy, spectrum monitoring etc. are presented. The designs are based upon two new frequency independent reflectors named as Step-Lane and Pyramidal. These are individually attached behind a pair of orthogonally polarized trapezoidal toothed planar log periodic antennas, resulting to an unidirectional radiation pattern with a considerable improvement in gain over the entire ultra wideband. The basic concept and mathematical design equations of these reflectors are presented. A very light weight real design of an ultra wideband dual polarized feed in the VHF/UHF range using a Step-Lane reflector has been presented together with results. It is felt that this kind of designs can work at microwave frequencies too. In the computational model of the antenna, the Step-Lane reflector was later replaced by the Pyramidal reflector and a pattern comparison was done. A close resemblance was found between the two results.