On the Response of a Directive Antenna to Incoherent Radiation

The relative response of directive antennas is dependent on the mechanism whereby the energy is conveyed. This fact, which often seems to be neglected, is of particular importance when the energy arriving at a receiving antenna can be represented in terms of a spectrum of incoherent plane-wave components. Such may be true frequently in the extraoptical propagation of microwaves. A study of an idealized situation is presented which compares the behavior of several pencil-beam antennas of varying aperture. A brief comparison with some recent observations is made.