Low Cross-Polarization Gaussian Tapered Post-Wall Slotline Antenna for Short Pulse Applications

A Gaussian tapered slot antenna based on post-wall structured slotline for improvement of cross-polarization for ultra-wideband applications is proposed and experimentally demonstrated. The antenna is composed of two pairs of Gaussian tapered slotline which have the same structure printed on both sides of the PCB, two metallic via arrays positioned along the slot edges, and two terminal resistors. The metallic via arrays are used to reduce the characteristic impedance of the conventional slotline which forma post-wall slotline and thus can be fed by a coaxial connector directly. More importantly, the balanced symmetrical post-wall structure ensures low cross-polarization levels of the antenna. The Gaussian tapered edges and the terminal resistors diminish reflected signal and thus can enlarge the bandwidth significantly. Good agreements between the simulated and the measured results have been observed. Results show that the proposed antenna exhibits a - 10 dB impedance bandwidth from 1.5 GHz to 20 GHz, a maximum realized gain of 12 dBi, and the broadside cross-polarization level is averaged about -32 dB in the lower frequency band and -25 dB in the higher frequency band with a maximum value of -22 dB in the whole working frequency band.