Enhancement of ultra-wide bandwidth of microstrip monopole antenna by using metamaterial structures

As wireless communications applications continue to require more and more bandwidth, there has been continued increase in demand for ultra-wide bandwidth antennas. Planar monopole antennas are generally suitable for mobile applications and hence we researched avenues to improve the bandwidth of this antenna structure. First part in this paper describes the design of novel compact and ultra-wide bandwidth (UWB) antenna. The basis for achieving the UWB operation is through using semicircular microstrip monopole antenna with modified ground plane as semi circular patch like umbrella shape. This shape produced bandwidth ranging from 2 to 30 GHz with discontinuities from 7 GHz to 10 GHz, from 12.5 GHz to 17.5 GHz and with a size reduction around 50% from conventional rectangular shape patch. Second part of this paper is focused on further improving in the antenna performance by using metamaterial structures such as Metallo-electromagnetic band gap structure (MEBG) and spiral artificial magnetic conductors (SAMC). The final novel antenna design provides an impedance bandwidth (S₁₁<-10dB) of more than 29 GHz corresponding to over 900% increase over the original bandwidth.