The recent growth in cellular communications has rapidly created a need for more radio channels. In order to make better use of the available frequency bands new access techniques such as TDMA (Time Division Multiple Access), FDMA (Frequency DMA) and CDMA (Code DMA) have been introduced. Still, the need for new channels is strong and new frequency bands have therefore been allocated for wireless communication systems.

These new communication systems, e.g. the European Personal Communication Network (PCN: 1710-1880MHz) and the North American Personal Communication System (PCS: 1850-1990MHz), use frequencies about twice as high as their predecessors (e.g. AMPS: 824-894MHz and GSM: 880-960MHz). However, at a time when our downtown areas already are littered with antennas, operators are not keen to install more.

One solution could be to replace existing GSM or AMPS antennas with dual band GSM/PCN or AMPS/PCS. This would reduce the windload of the towers, the number of feeder cables and the whole  cost of tower installations. If the dual band antennas were to be dual polarized also, the four antennas today being needed for receiving the PCN and GSM bands in a sector, could actually be replaced by one only.