Prompt aperture efficiencies of impulse radiating antennas with arrays as an application

A concept of prompt aperture efficiency is introduced for the purpose of co mparing and optimizing the performance of impulse radiating antennas (IRAs) . The aperture efficiencies of popular lens and reflector IRAs are computed as the ratios of peak radiated power densities on boresight compared with that produced by an ideal IRA with an aperture of equal area and equal tota l input power. Loss of aperture efficiency occurs through two distinct mech anisms: from power that falls outside the aperture and is lost and from non uniform power and polarization distributions within the aperture. Both loss mechanisms are addressed, and means for increasing efficiencies are identi fied. The optimum aperture for a given feed structure is derived. Prompt ap erture efficiencies approaching 100% are feasible in TEM-born arrays and si milar structures.