Abstract: A dual frequency antenna is mounted into a ground plane with an opening having a first predetermined length and width and under which a container having a second length, width and also depth is mounted. The dimensions of the opening and container are selected according to the operating characteristics of the antenna. The container includes four sides and a bottom plate. A first microstrip element is mounted in the container in alignment with the ground plane in the opening and it has a length and width less than the first predetermined length and width. The second length and width of the microstrip element is selected to optimumly perform at a first operating frequency. A second microstrip element is mounted in the container and is separated from the bottom plate by a preselected difference and separated from the first plate by a second preselected distance and its operating frequency is selected to be less than the first operating frequency.