Wide bandwidth current and impedance meter

摘要

The current and resistance meter involves measuring a voltage across a reference resistance. The meter has a three coil transformer (35) linked by a coaxial cable (36) with a neutral, an outer conductor, an input and an output, and a differential amplifier (31) links the neutral of the coaxial cable to the output side of the transformer. The current determination or reference resistance (38) is connected between neutral and the outer conductor of the three coil transformer, and a voltmeter (30) measures the output voltage of the differential amplifier (31) to determine the current flowing through the resistance (38). An earthing device (33) provides a connection between the outer conductor of the coaxial cable to earth at both high and low frequencies having a high impedance at low frequencies and low impedance at high frequency.