Wideband Limiter Protector for radar and electronic warfare systems

Naval vessels today are equipped with a large variety of electronic equipment for radar functions, communications, navigation, countermeasures, and others. Many of those shipboard systems operate with transmitters emitting thousands of watts of power inmicrowave frequencies, and the presence of high-power transmitters in close proximity to sensitive receivers. This proposal is addressed to the development of broadband microwave limiters using wide band-gap devices of those technologies suitable forapplications in microwave frequencies, namely gallium-nitride (GaN). So far, the prospect of high-power microwave amplifiers using GaN devices has been investigated at length, but there has been only a limited study of application of those devices assignal control devices such as switches and attenuators and no reported studies of limiters and LNAs. The proposed program will be focused on development of limiters and LNAs for receiver protection. The Phase 1 effort will lead to a full assessment ofcapabilities of GaN microwave limiters and LNAs, definition of design goals for broadband limiters, LNAs and design approaches. The ensuing Phase 2 program will be focused on implementation the limiter design and demonstration of its capabilities.Successful implementation of limiters in MMIC form will protect sensitive shipboard receivers against both friendly radar emissions and hostile high-power microwave (HPM) threats. Rugged LNAs will further enhance the survivability of receiver front ends.Ultimately, limiters for receiver protection will find applications in all microwave equipment subject to potentially hazardous radiations, including commercial receivers for wireless communications and satellite receivers.Hittite Microwave Corporation has a history of limiter development of novel circuits for protection applications including stacking FETs in series to withstand high RF voltages, and a method of feed-back controlling attenuators for receiver protection. Amethod of implementing a MMIC notch filter was also demonstrated to suppress high levels of selected harmful radiation, and the limits of purely passive limiters based on conventional GaAs FET devices were investigated. Recent advances in wide band-gapsemiconductors show a promise of devices with a high break-down voltages that may ultimately lead to integration of limiters into MMIC modules. GaN technology is an emerging technology for high power microwave components including amplifier and control components. While most GaN development is currently focused on amplifier components GaN may also prove superior for many control componentapplications such as high power switches and limiters as well as threat resistant LNAs. These components will find application in cellular base stations and other communications equipment.