Direct Measurement of the Loss Conductance of Condensers at High Frequencies

A method of measuring the losses of a variable air condenser at high frequencies is described in which the condenser under test and the standard are connected in series as part of a tuned circuit. A radio-frequency voltage of resonant frequency is impressed on this circuit for a stated value of the standard. The unknown is then removed and the standard adjusted to resonance. The voltage across the tuned circuit is readjusted to its initial value by placing a conductance across the standard. The design of the standard condenser requires special considerations which are discussed. A self-biasing valve voltmeter, which is not critical to variations in power-supply voltage, is used. The results of measurements on several specimen condensers are given. A method of extending the measurements to higher frequencies is shown.