The measurement of errors in radiogoniometers at high and very high frequencies

A review of existing methods of measurement of the instrumental errors in inductive radiogoniometers is followed by detailed descriptions of three methods that have been used in the high- and very-high-frequency bands (3¿100 Mc/s). The first, a field-coil interconnection method which requires no apparatus other than a signal generator and detector, has a limited application, but this disadvantage is offset by its simplicity. The second method makes use of a resistance potentiometer capable of a high order of accuracy at frequencies up to 30 Mc/s. In the third method two inductive piston attenuators are used. This apparatus has a very high order of accuracy, and may be used at the highest frequencies now employed for direction-finding purposes. The importance of the measurement of errors due to the electrical asymmetry of the field coils and search coil is emphasized, and methods that have been used at high and very high frequencies are described. The accuracy and limitations of the methods are discussed and their merits compared. Details of the construction of the measuring apparatus and of its calibration are given, and typical error measurements made on various goniometers are included.