Analysis of Rotationally Misaligned Stators in the Rotary-Vane Attenuator

Two types of errors are caused by misaligned stators in the rotary-vane attenuator. For each type of error the actual attenuation will differ from the indicated attenuation values throughout most of the usable range of the attenuator. This analysis illustrates that these two types of errors are related to the technique of alignment used in establishing the zero reference of the rotating vane to the stator vanes. Equations pertaining to these errors are discussed and are solved with the aid of tables of attenuation error as a function of vane angle error for rotary-vane attenuators. Graphs of both types of errors are presented determining the parameters needed to establish limits of machining tolerances for each waveguide size.