Electrical Measurements at Ultra-High Frequencies

Part I. A modified form of the long-line equations for use at ultra-high frequencies is given. A complete solution is obtained for a pair of parallel wires bridged at each end by a general impedance. The solution is in the form of expressions giving the voltage across, and the current through one of these impedances. Conditions are given under which the current or voltage becomes a maximum, as well as formulas for these maximum amplitudes. Special cases are discussed and expressions are derived for use in the measurement of reactance and resistance. Part II. A convenient form of parallel wire system for ultra-high-frequency measurements is briefly described, and its constants are listed. The use of a tandem bridge is explained. The general problem of measuring current and voltage at ultra-high frequencies is considered. A method is mathematically derived for obtaining the calibration characteristics of current and voltage indicators; the method is applied experimentally to determine such characteristics for a thermal milliammeter and for the symmetrical screen-grid voltmeter. The scale factor is discussed. Part III. The mathematical theory of Part I is applied to obtain two methods for measuring respectively high and low reactances. These are used to measure the reactances of various wires, coils, condensers, thermal milliammeters, vacuum thermocouples, etc., and to study series and parallel resonance circuits at ultra-high frequencies. Part IV. The general problem of resistance at ultra-highfrequencies is discussed. The mathematical theory of Part I is applied to the measurement of resistance.