ELECTROMAGNETIC TRANSDUCER

摘要

There is disclosed an electromagnetic transducer for the transmission and reception of ultrasonic waves in the touchless testing of metal workpieces, particularly made of steel, in the shape of sheet and strip material. The transducer is arranged for continuous testing, particularly as applied to continuously advancing material, by wavelength spectroscopy and particularly modal spectroscopy of received ultrasonic waves. To this end, the transducer comprises a pair of transducer segments each of which has a set of mutually parallel conductor tracks formed on a substantialy planar printed circuit board in which the frequencies and wavelengths for each segment can be preset in a matrix logic circuit having a short time sequence. The conductor tracks comprise windings arranged to be connected for operation through a set of switching elements in such a manner as to produce in various switching states of the switching elements a plurality of wavelengths for each frequency. The wavelengths being proportionally related to each other by small integral numbers.