Inhibitory effect of differential transmission with two coaxial cables on interference

The distortionless transmission of the signal through the transmission line is the prerequisite to ascertain the waveform and value of the electromagnetic field under test accurately. In consideration of the bandwidth, power capacity, loss, shielding efficiency and size, the coaxial cable is often used in the UWB measurement system. It is indicated in this paper that the single coaxial cable can produce interference to the transmission signal and the reason of the interference is explained. The result of the computation by a numerical method testifies that the interference does exist and can cause aberration of the signal when one coaxial cable is used as the transmission line. It is put forward that the interference can be eliminated effectively by differential transmission using two coaxial grounded cables. The prominent suppressing effect of the transmission method is certified contrastively by simulation. A dipole with the two coaxial feeder is fabricated and tested. The experiment shows that the single coaxial cable caused obvious interference and the interference was eliminated by the differential operation of the output voltages from the two coaxial cables.