Use of Baluns

The purpose of the Baluns is to enable transmission lines and equipment having different impedances to be matched and connected for maximum transfer of the signal with minimum effect to the transmitting signal such as insertion loss, waveform distortion and minimum reflection of the signal. The device should be as transparent as possible for the range of frequencies that it is designed to operate

No flat cables should be used at the Balanced end, only twisted pair cables preferably with a good number of twists per unit length, because when a cable is exposed to a noise source the noise signals are induced into the cable. Flat cables pick up different amounts of noise by the two wires due to the finite difference of distance of the conductors from the noise source with resultant level of noise being picked up and transferred into the system, whereas the wires that are twisted together fairly tightly, occupy all the various positions possible equally, and the wires will have been exposed to the same amount of noise and at the receiving end cancelling one another due to the opposing phases. For transmission of high frequency, twisted pair cables with more twists per unit length is preferred. Twisted pair cables have been rated as CAT 3, 4, 5 & 6 according to frequency handling capabilities, Near End Cross-talk (NEXT) and Attenuation Cross-talk Ratio (ACR).