Minimum Q of small antennas

A detailed analysis is presented which shows that the method introduced by Collin and Rothschild in 1964 for finding the time averaged stored energy in the electromagnetic field surrounding a small antenna is valid and leads to correct evaluation of the minimum Q of a small antenna. An alternative method for finding the minimum Q of small antennas is also presented. This method is based on the natural complex resonant frequency of a TE or TM mode tuned to resonance by a reactive surface impedance on the minimum circumscribing sphere that encloses the antenna. This alternative method of finding the minimum Q of a small antenna is shown to give results in close agreement with the earlier results. The paper also provides a critique of recent work by D. M. Grimes and C. A. Grimes in which they claim that smaller antenna Q's can be obtained than that found by earlier investigators. It is shown that the results obtained by Grimes and Grimes are based on incorrect hypothesis and are wrong.