Time Modulated Frequency Diverse Array Using Fractal Antenna

This paper presents a novel configuration of a fractal circularly polarized frequency diverse array (FDA), designed to reduce side lobe levels (SLL) through the application of time modulation technique. The side lobe levels are suppressed to below −22.5 dB with gain equal to 31 dBi. The on-time instant and on-time duration are optimized using the Particle Swarm Optimization (PSO) algorithm. The produced radiation pattern has a pencil-shaped time-invariant and range-angle dependent beampattern. A Linear Cantor FDA array and planar Sierpinski FDA arrays are utilized to achieve the desired radiation pattern at 10 GHz with multiband capabilities for FDA radar applications. The curl spiral constant is a =0.18 mm/rad with 3.2 mm height. The start and end angles <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\emptyset$</tex> of the curl are chosen to be <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$6\pi$</tex> and 26.3 rad, respectively. The gain of the curl antenna is 6 dBi. Printed curl antennas are investigated and analysed using CST Microwave Studio and Matlab software.