Since the mid-1970s, the US Army Communications-Electronics Command (CECOM) has conducted research and development efforts in the area of extremely high frequency (EHF) communications for tactical military applications. These efforts have been driven primarily by the need for reliable short to moderate range low probability of intercept (LPI) and jam resistant communications in a variety of applications ranging from line-of-sight multichannel transmission for down-the-hill radio remoting to short range, omnidirectional, covert push-to-talk voice communications for combat net radio users. Development has been concentrated in two frequency bands available for military communications: 36.0 to 38.6 GHz and 54.25 to 58.20 GHz. A number of EHF communications systems in both bands have been successfully developed and extensively tested in both the laboratory and tactical military environments. The paper describes and discusses the applications and demonstrated advantages of the EHF spectrum, and CECOM's efforts to exploit this band for tactical terrestrial military communications. >