This paper presents a compact microstrip antenna for frequency agility using pin diodes . The frequency agile antennnas are found in literature review with various levels of design complexity to achieve desired radiation parameters for a given application. In this paper, a novel approach for design of a reconfigurable rectangular microstrip patch antenna (RRMSA) with inset feed is presented. The antenna is designed for multiband frequency which includes Wi-Fi(2.4 and 5.6 GHz) and C band (4 - 8 GHz). The proposed antenna also generates narrow band and wideband combination by switching the pin diodes on the ground slot. The main features of rectangular microstrip antenna are FR-4 substrate with dielectric constant of 4.4 loss tangent 0.02 and height of substrate 1.6mm. The antenna size is 45mm x45mm x1.6 mm. The design technique is used on reactive loading by cutting U slot and switches are employed to shift the operating band by varying the electrical length of the slot of radiating patch. Pin diodes are used as RF switches. The performance of the antenna is simulated using ANSYS HFSS