Energy consideration in space-time synthesis of collimated pulsed apertures

We consider measures for an effective realization of short pulse antennas. We discuss such new concepts as TD multipole decomposition, time-dependent reactive and radiative energies and introduce the ratio between them, termed the time-domain Q as a measure of the radiation effectiveness. These near-zone characteristics are examined vis a vis the far-zone characteristics, the time dependent radiation pattern and the directivity. The theory is used to evaluate and compare several different realizations of highly collimated, short-pulse aperture distributions.