The present invention improves measurement of the formation induction response in the presence of the primary magnetic field generated by a logging tool's transmitter. In a exemplary embodiment of the present invention, a structure is provided having a new combination of electrical and mechanical design features which provide logging tool for internal calibration and checking of antenna performance and characteristics before during and after well logging operations. In one aspect of the invention a logging tool is provided comprising a verification winding for coupling a verification signal into the receiver coil.