A planar antenna includes a ground plane on a substrate, a radiating element coupled to the ground plane on the substrate, and a feed line. An impedance tap point is defined by a connection between the feed line and the radiating element and the length of the radiating element defines the resonant frequency of the antenna. A first portion of the radiating element includes an impedance adjustment mechanism for defining the impedance tap point of the antenna and consequently the impedance of the antenna. A second portion of the radiating element includes a frequency adjustment section which adjusts the length of said radiating element and consequently the resonant frequency of the antenna.