Abstract :
For a resonant cavity composed of a section of transmission line, shorted at both ends, an equation relating the unloaded Q of the cavity to the attenuation constant alpha of the line was recently reported by Yeh [ibid., vol. 50. p. 2145, October, 1962]. He derived the relation between alpha and the phase constant (beta) in terms of phase velocity and group velocity of the line under the assumptions that the shorting plates do not contribute to the loss and that alpha is small compared to the phase constant beta. It is the purpose of this note to show that the assumption alpha be much smaller than beta is not necessary.
