Author Description

In this report a number of the basic ideas and assumptions involved in the analysis of electrically small antennas is considered. Poynting's theorems in both the time and frequency domain cases are derived, and the conditions under which they are mathematically applicable are examined. Their relationships with stored energy, both time dependent and time average, are derived. Resistive and reactive power flow into circuits is examined and compared with the power flow across a closed surface surrounding an antenna. It is found that while using this approach to find the input or radiation resistance of a single port antenna can be justified, using the same approach to obtain the antenna input reactance cannot be justified. The antenna quality factor (Q) concept is considered from first principles, various forms of Q are explored for series and parallel circuits, and the relationship of the Q to the antenna bandwidth is discussed. A consistent theoretical foundation and a physical understanding of the radiation and stored energy properties of general antennas are constructed to determine the performance limits on electrically small antennas.