The invention provides a compact patch antenna having a cavity underneath the driver patch, so that the electromagnetic volume of the antenna is expanded without increasing the overall area of the antenna. More specifically, the compact patch antenna comprises a base layer having a cavity, a ground plane located on the base layer, and having an opening over at least a portion of the cavity, a substrate located on the ground plane, and a driver patch located on the substrate. The invention further provides a method for constructing a compact patch antenna, comprising the steps of providing a base layer having a cavity, providing a ground plane located on the base layer, and having an opening over at least a portion of the cavity, providing a substrate located on the ground plane, and providing a driver patch located on the substrate.