P. G. Semashko, N. G. Parhomenko, A. E. Okhrimenko

In the last few years in some counties the idea of radar using the external illumination of television and radio transmitters, semiactive radar, has received practical development. Major advantages of semiactive radar are based on the absence of its own transmitter. It allows achieving absolute radio stealthiness, does not require the assignment of deficit radio frequency resource and there are no damage effects on environment ecology and on people. This kind of radars do not create antenna crosstalk, are cheaper in production and maintenance than active ones. High altitude of antenna elevation and the power of the broadband transmitters in use create suitable environment for detection of low or small targets. Potential characteristics of semiactive radars that use the electromagnetic fields created by analog and digital television and radio transmitters for target illumination are considered in the paper. General requirements for illumination signal sources are formulated. It is shown that ground-based transmitters such as existing networks of analog television and radio as well as deploying networks of digital television and ratio meet these requirements. The advantages of ground-based digital television and radio transmitters are shown. Basing on the ambiguity function analysis for these signals the radar characteristics of detection and resolution that shows the advantages of digital signals are calculated.