Proceedings PaperLimitations to directive time domain beams
|Format||Member Price||Non-Member Price|
This paper examines the interrelationship between the size of an antenna structure and its ability to produce narrow beam radiation when excited by signals of arbitrary time dependence. By using the well known spherical mode expansions for the scalar wave equation, a network theoretic interpretation is developed which is valid for all frequency. This allows the decomposition of the problem of studying the time domain behavior of a radiating structures into two distinct parts. The first deals exclusively with the angular dependence of the radiation, while the second deals only with the frequency content or corresponding temporal behavior of the excitation. The two parts are connected by the number of modes that are excited and their relative excitation strengths. The inter-relationship between the size of a radiating structure, the minimum beamwidth that it can efficiently produce and the resulting limitations in creating packets of radiation that are localized in both time and space for a variety of wideband excitations including baseband waveforms is considered.