Antenna impulse response and the generalized antenna scattering matrix

We address here the problem of characterizing antenna performance in the time domain as simply as possible. Currently, no standard terms have been defined, and this can be a problem for buyers and sellers of wideband antennas. This problem becomes apparent if one imagines attempting to describe antennas in the frequency domain without a widely accepted definition of gain. In this work, we recast the time domain antenna equations into a simple form. This allows us to very naturally extend into the time domain a collection of commonly used antenna terms, including gain, realized gain, antenna factor, radar cross section, and scattering cross section.