Abstract: To trace and locate the travelling pigs in the pipeline, a exceptional low working frequency should be selected for the tracer signa1 transmitter.The auther presents here the ways to calculate frequency and test method based on his expericnces in making this smal1 ULF transmitter.The paper begins with of the working out of an antenna of special structure and analyzes a number of new problems arising therefrom.Some scientific deta for optimum design of the system as well as the calculation of the sensitivity of the transmitter are presented.