ABSTRACT
Radio frequency (RF) and microwave systems have played a significant role in service of defense objectives since the dawn of the electronics era. Among the earliest applications of RF electronic equipment for defense was the area of communications. Battlefield dominance and strategic victories have historically relied on the ability to communicate effectively over long distances in real-time, as exemplified by the courageous story of Cher Ami, a carrier pigeon flown by the U.S. Army Signal Corps in Verdun France during World War I [1]. In that same conflict niche communications applications appeared for radio, as air-ground radio communications facilitated reconnaissance missions flown by military pilots [2], and ground communications were used to warn of impending gas attacks. The widespread use of radio communications, however, was largely limited by the bulkiness of available field equipment [3]. The broader importance of radio transmissions increased during the latter portions of the twentieth century, facilitating applications such as the direction of troop movements and ordnance targeting, and enabling radar as a key defensive systems for early warning and target recognition. Simultaneously, these same signals were being exploited by adversaries able to derive information such as broadcast location, representing perhaps the first instances of what is currently called electronic warfare (EW) [4]. Similarly, forces began
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deploying systems that either had specially engineered microwave signatures or actively sought to deceive an opposing force through countermeasure broadcasts and the like.
