Designing Resistive Attenuating Networks

This paper represents a collection of material, largely old but in part new, which is to advantage presented in one place for ease of reference and use, and which is not known to be available elsewhere in this collected form. Herein are recorded, in outline, the derivations of expressions for calculating the various elements of resistive attenuating networks or, in more common parlance, pads. The derivations are general, for the case where the networks are inserted between unequal terminal impedances; simplifications yield the more familiar expressions for corresponding elements of networks inserted between equal impedances. Inspection of these expressions shows that the process of calculation can be facilitated by a tabulation of the values of several factors which are multiplied by the terminal impedances in obtaining the resistances of the individual elements. These factors are all functions of the ratio between the power put into the pad and the power delivered to the load. A tabulation is provided of values of the most useful of these factors for a large number of attenuation values. There are also tables and curves showing the smallest attenuation possible in a tapered T or L pad as a function of the ratio of the two unequal impedances between which it is inserted, together with the reflection loss between the same impedances with no network inserted.