Ultra-Wideband Metamaterial-Loaded Microstrip Array Antennas using Fibonacci & Fractal Geometric Patterns, Design and Modelling

Abstract

In this study; theory, design and modeling of a new topology of ultra-wideband (UWB) metamaterial (MTM) loaded microstrip array antenna using Fibonacci & fractal geometric patterns are analyzed. This antenna is made basically from many monopole elements which are loaded by complementary metamaterial transmission line (CMTL) unit cells. The distributed CMTL element, contains a Koch-shaped expanded complementary single split ring resonator (CSRR) pair. At first step, the UWB microstrip array antenna designed with two CMTL-loaded monopole element. So, using an iterative method based on the Fibonacci and fractal geometry patterns, the array antenna is expanded. As the order of iteration increases, the impedance bandwidth of the proposed array antennas improve more, and the radar cross section (RCS) decreases. the impedance bandwidth of the proposed third-order Fibonacci and fractal CMTL-loaded array antennas are 250 MHz and 539 MHz more than the two-element CMTL-loaded array antenna, respectively. Finally, this paper presents an improved method to extract the parameters of an equivalent circuit model of the proposed MTM-loaded array antenna. Verification of the equivalent model have been validated utilizing ADS software. The obtained model, in addition to numerically efficient in comparison with the full wave analysis utilizing the moment method, gives a good physical insight to the mutual coupling mechanism of the array antenna.