Classification of bridge methods of measuring impedance

AN ANALYSIS of the requirements for satisfactory operation of the simple 4-arm bridge when used for impedance measurements is given in this paper. The various forms of bridge are classified into 2 major types called the ratio-arm type and the product-arm type, based on the location of the fixed impedance arms in the bridge. These 2 types are subdivided further, based upon the phase relation which exists between the fixed arm impedances. Eight practical forms of bridges are given, 3 of them being duplicate forms from the standpoint of the method of measuring impedance. These bridges together allow the measurement of any type of impedance in terms of practically any type of adjustable standard. The use of partial substitution methods and of resonance methods with these bridges is discussed and several methods of operation are described which show their flexibility in the measurement of impedance.