Present and future evolution of radars

The status of radar immediately after World War II is examined, and changes in radar technology from 1950 to the present are discussed. It is found that there have been no significant changes regarding frequency bands, except for an extension to Ku Band. In conventional air defense ground stations, there was a simultaneous increase in peak power and antenna surface. Other changes were related to the introduction of pulse compression technology, the reduction of parasitic antenna sidelobes, and the use of digital processing. Present trends are concerned with the satisfaction of performance expectations which have been drastically increased. Attention is given to antenna pattern purity, the choice of antenna type, tolerances required to obtain radiation patterns, quantified phase shifters, periodical errors, the case of a reflector, and the applications of periodical perturbations to autoadaptive arrays.