An antenna of the present disclosure has a housing having a shallow cavity in the housing and a flat, disk-shaped radiating element disposed in the shallow cavity, the radiating element having an arc shape slot. In addition, the antenna has a substantially circular parasitic element disposed in the shallow cavity on the bottom of the housing. The antenna operates as a half-wave antenna at a frequency range of 450 MHz to 470 MHz and as a full-wave antenna at a frequency range of 902 MHz to 928 MHz.