High-Power RF Technology for Solid-State Radar

High-power solid-state RF technology has historically been used at the radiating-element level in active electronically-scanned array (AESA) radars with element power combined spatially in front of the array. More recently, the availability of affordable high-power LDMOS and GaN transistors and low loss power combining topologies and distributed-aperture antenna arrays enable the use of this technology for non-AESA radars. This is becoming true even in the case of large power-aperture product radars essential for applications such as long-range space surveillance. This presentation will outline the fundamental technology of Silicon and GaN power transistors, and their employment in power amplifiers as applies to radar systems from UHF to W band. Tradeoffs between pulsed operation with monostatic (shared transmit and receive) antenna apertures and CW operation with bistatic (separated) transmit and receive antenna apertures are discussed. Techniques needed to implement monostatic antenna architectures such as the use of high-power PIN diode duplexers and pulsed drain biasing, and their associated impact on system noise, are discussed. Power-combining techniques applicable from UHF to W band are discussed along with the tolerance of these techniques to the failure of individual inputs.