EXPERIMENTAL INVESTIGATIONS ON A QUASI- OG PERIODIC PRINTED SLOT ARRAY

Abstract

Printed antennas were first demonstrated in the early seventies. Since then, they have gained great popularity owing to their numerous advantages particularly low cost, light weight, thin profile, ease ofmanufacture etc. However, these antennas have a number of disadvantages primary of which are narrow bandwidth, low efficiency, low power handling capacity etc. Several methods have been attempted to overcome the limitation of narrow bandwidth, off these, a fairly successful method was using log-periodic techniques. However, thus far all literature specifies use of patch resonators as the radiating elements. Slot radiators have the advantages of very low cross polarisation and spurious signal-free radiation patterns as compared to patch radiators. lit this dissertation, resonant slots are used as the radiating element of a seven-element log-periodic array to cover the frequency band from 8GHz to 12 GHz. Experimental results have been reported on the radiation pattern and gain of this array. Subsequently, the array was backed by a conducting reflector and cavity and experimental results obtained. Finally, impedance matching, at the first slot from the feed end, was attempted for the cavity backed array and experimental analysis repeated