Title :
A method for the evaluation of small antenna Q
Author_Institution :
Research In Motion, Waterloo, Ont., Canada
Abstract :
A method is presented to calculate the quality factor (Q) of small antennas, which is based on the understanding that for a small antenna the total energy in Poynting theorem can be easily separated into the stored energy and radiated energy by using the low frequency expansions. The Poynting theorem in frequency domain provides an equation on the stored electric and magnetic energy while the Poynting theorem in time domain can be used as another independent equation for the stored electric and magnetic energy. By solving these equations the stored electric and magnetic energy can be obtained, thus, making the Q calculation possible.
Keywords :
Q-factor; antenna radiation patterns; dipole antennas; frequency-domain analysis; loop antennas; time-domain analysis; LF expansions; antenna performance; antenna quality factor; circular loop antenna; dipole antenna; frequency domain Poynting theorem; inverted L antenna; low frequency expansions; quality factor; radiated energy; small antenna Q; stored electric energy; stored magnetic energy; time domain Poynting theorem; Antenna theory; Bandwidth; Difference equations; Frequency domain analysis; Helium; Impedance; Magnetic domains; Magnetic separation; Q factor; Receiving antennas;
Journal_Title :
Antennas and Propagation, IEEE Transactions on
DOI :
10.1109/TAP.2003.814755
