Directivity, super-gain and information

In this paper some analogies between antenna theory and the theory of optical resolving power are analyzed. The effect of the finite size of a rotating antenna on the informational content of the echo is discussed, without taking into account noise. From this point of view, the most important feature of the aerial is the highest angular frequency which is contained in its radiation pattern. Supergain is possible because no upper limit exists for this frequency. A simple method is pointed out for synthesizing a radiation pattern containing any prescribed set of finite angular frequencies. A numerical example is worked out.