RF directional wattmeter

An electronic instrument module for detecting and measuring the forward and reflected RF voltage wave signals on a coaxial transmission line. The instrument is integral with a coaxial line section adapted to be electrically inserted in a tubular transmission line, the line section having an elongated conductive metal body with a central cylindrical opening with a coaxial center conductor therein electrically insulated from the metal body. The metal body also has a transverse opening communicating with the central cylindrical opening and adapted to receive an inductive pick-up coil mounted on the body for rotation in the opening about an axis normal to the axis of the line section. The pick-up coil is responsive to the voltage wave signal on the transmission line. Also, mounted on the metal body are a D'Arsonval meter movement and circuit means connecting the pick-up coil to the meter movement so that the meter provides an indication of the level of either the forward voltage wave signal or the reflected voltage wave signal depending on the orientation of the inductive pick-up coil.