Teaching antenna reception and scattering from a time-domain perspective

The reception and scattering of an incident plane wave by simple wire receiving antennas are analyzed. The approach is the same as used in an earlier paper where the radiation from similar transmitting antennas was considered. First, analytic expressions are obtained for the current and field of a basic traveling-wave receiving element. Then, a more complicated receiving antenna is viewed as a combination of basic traveling-wave elements, and the current and scattered electromagnetic field of the antenna are obtained by superimposing the currents and fields of these elements. The emphasis throughout is on the use of the time domain, viz., pulsed excitation, to establish physical understanding of the process of radiation/reception, unlike conventional treatments that use time-harmonic excitation. Two examples are discussed in detail: reception by a loaded dipole antenna and scattering by a straight wire. The relationship between the transmission and reception for the dipole, i.e., reciprocity, and the phenomenon of resonant scattering for the wire are also examined.