Target classification and EM-compatibility in VHF/UHF radars

VHF/UHF radars are affected more severely than conventional radars by the problem of electromagnetic compatibility since the desired band of operation is densely covered by other services. Avoiding disturbances from other services by adequate radar signal processing is only one aspect while the more stressing problem to be solved is to operate a radar without interfering other users of the radio band. Another feature, to some extent unique to low frequency radars, is the restriction to non-imaging classification techniques in the case of a non-cooperative target, since the required radar bandwidth for range or range-Doppler imaging can hardly be achieved at metric wavelengths. At FGAN-FHP, the VHF-experimental radar (LARISSA-large wavelength radar with dependent spectral signal adaptation) has been improved during the years to enable its use as a testbed for the verification of helicopter classification strategies and electromagnetic compatibility approaches in low frequency radar systems. These aspects are discussed.