A Multiband Low Cost Fractal Antenna based on Parasitic Split Ring Resonators

This study presents the design of a low-cost fractal antenna loaded with parasitic edge-coupled (EC) split ring resonators (SRR). Parasitic EC SRR elements result in improved impedance matching leading to improved bandwidth. The basic resonant structure is a circular patch antenna designed at 3.2 GHz on low-cost FR4 substrate with relative permittivity 4.4, and 1.6 mm thickness. A single iteration of circular patch and slots is used to make it fractal and in order to achieve multiband performance, the antenna is inset fed by a 50 Ω microstrip line. A prototype of the proposed antenna is fabricated and tested for results, a comparison between fractal antenna with and without SRRs is made and the results confirm that a better impedance matching is achieved in the later case, also a 3% increase in bandwidth is achieved at 8.5 GHz. A good agreement between simulated and measured results is obtained, an estimated gain of 13.3 dB is provided by the proposed antenna. The overall dimensions of the antenna are 45 mm × 45 mm and it may be used for wireless applications at 3, 5, 6.8, 7.5 and 8.5 GHz with an average bandwidth of 200 MHz.