A New Method to Reduce the Impact of the Common Mode Currents for Field Measurements on Symmetrical Antennas

Common mode currents on the feeding line may significantly impact on antenna radiation measurements. In this paper, we propose a novel technique to discriminate antenna radiation from the total field produced by the antenna-feeder set. Our method is based on averaging a normalized, magnetic field measured at different distances away from the antenna under test. The common mode current has a fluctuating contribution that cancels out in the average figure. The proposed approach was validated by measuring a symmetrical dipole fed through a coaxial cable; the probe antenna was a small square loop.