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 3.2GHz on low-cost FR4 substrate with relative permittivity 4.4, and 1.6mm 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 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 8.5GHz. A good agreement between simulated and measured results is obtained, an estimated gain of 13.3dB is provided by the proposed antenna. The overall dimensions of the antenna are 45mmx45mm and it may be used for wireless applications at 3, 5, 6.8, 7.5 and 8.5GHz with an average bandwidth of 200MHz.