An antenna is provided having a primary helical coil (102) and a secondary helical coil (104) contra-wound relative to the primary helical coil. Switchable coupling between the coils allows the antenna response to switch from lower to higher frequency responses within the same Ultra High Frequency (UHF) band. A bandwidth of the same physical length antenna can be increased up to twice the bandwidth or for a fixed bandwidth, the antenna length can be shortened. For the high frequency band, when the secondary helix is disconnected from the primary helix, the primary coil operates as a interferer notch out to improve interference rejection, to reject unwanted signals from nearby radios transmitting in frequencies separated by duplex spacing, such as Terrestrial Trunked Radio (TETRA) and cellular Global System for Mobile (GSM) communication bands.