In this paper, the authors present the design and development of slotted rectangular microstrip antenna for quad band operation and ominidirectional radiation characteristics. The quad bands are achieved between 4.81 to 16 GHz. The magnitude of operating bandwidth has been enhanced to a maximum value of 3.29, 17.22, 36.44 and 43.33% by varying the width of vertical slots on the patch. This enhancement does not affect the nature of ominidirectional radiation characteristics. The proposed antenna is simple in its geometry and has been constructed from conventional rectangular microstrip antenna by placing vertical slots on the patch and a ground plane of height equal to the length of microstripline on the top and bottom surface of the substrate.