Q-meter measurements on resistors

The operation of a Q-meter, in conditions when the circuit Q-factor is very low, has been investigated. Many of the approximations usually valid for high-Q-factor circuits have been shown to lead to large errors for low-Q-factor circuits. The modified formulae valid for all Q-factors have been derived. Particular attention has been paid to substitution methods, both series and parallel, and techniques are described to permit use of these methods over a wider range than usual. Experimental illustration of the theory is given.