The WU-660 Receiver Transmitter Antenna (RTA) is an integrated unit which incorporates transmitter, receiver, and antenna into a single unit. The WU-660 accepts either a 10 inch or 12 inch flat-plate radiator with transmitter and receiver components mounted on the rear of the antenna. The remainder of the circuitry is contained in the electronics package which forms the RTA base. The WU-660 is designed for cantilever mounting on the front bulkhead of the aircraft with line-of-sight stabilization employed. The WU-660 incorporates all the circuits required for transmission, reception, signal processing, scan conversion, serial data and control interface. The WU-660 also interfaces with the electronic flight instrument system (EFIS) and with the multifunction flight display (MFD). Additionally, the RTA incorporates the antenna positioning and control mechanism. The WU-660 generates and receives X-band high energy to detect weather and to map ground features. The 9375 MHz transmitted signal from the magnetron is routed to the antenna through the circulator. The size of the radiator (flat-plate antenna) determines the maximum range. The WU-660 accepts 10 Inch, 12 Inch, 15 Inch, or 18 Inch flat-plates that must be ordered in a kit.

The WU-660 is used in the Primus 660 Color Radar System. This system is a lightweight, X-band color digital radar with display designed for weather location and analysis, and for ground mapping. The display for the system can be either a dedicated radar indicator or the radar system can be operated in conjunction with electronic flight instrument system (EFIS) and multifunction display (MFD) equipment. This system detects storms along the flight path of the aircraft and gives the pilot a colored visual indication of storm intensity. In weather detection mode, target returns are displayed at one of five video levels. In ground mapping mode, video levels of increasing reflectivity are displayed as black, cyan, yellow, and magenta.