Plessey AR-320

The AR-320 is a 3D early warning radar developed by the UK's Plessey in partnership with US-based ITT-Gilfillan. The system combined the receiver electronics, computer systems and displays of the earlier Plessey AR-3D with a Gilfillan-developed transmitter and planar array antenna from their S320 series. The main advantage over the AR-3D was the ability to shift frequencies to provide a level of frequency agility and thus improve its resistance to jamming.

The system was designed for sales to the Royal Air Force and a NATO contract for mobile radars on the southern flank of Europe. In 1983, after an extended contest against the Hughes Air Defence Radar, the Royal Air Force ordered six AR-320 systems for their newly forming IUKADGE network under the service name AMES Type 93. The AR-320s were to be held in off-site locations and quickly moved to pre-surveyed areas in case the main radars in the network were attacked. In service, the AR-320 proved to be much less robust than advertised and was ultimately used only in fixed emplacements.

As the radar market grew more demanding and new solid state systems began to replace former vacuum tube systems as high-power microwave sources, the system was extensively redesigned as the AR-325, which, through a series of mergers, became the modern BAe Commander series.