Annular ring embedded L-slot rectangular microstrip patch antenna

Micro-strip patch antenna's have been widely used for the application of RF and wireless system because of their small size, light weight and easy realization. In this paper we have reduced the resonating frequency by lengthening the excited surface current path without increasing antenna length and analyzed the antenna parameters by changing the feed technique. On the introduction of an annular ring in between the symmetrical L-slotted patch the resonance frequency is reduced by 29.91% when edge-fed or microstrip-line feed technique is used. The coaxial feed results in dual band operation of the antenna (in C-band and X-band). Small sized single band microstrip patch antenna works in ISM band with the bandwidth of 100MHz while, the dual-band microstrip patch antenna works in Wi-Max and 4G in the bandwidth of 25MHz and 85MHz.