l induct- Attenuation 2.1dB/100m @ 1MHz ance between two or more windings on a ferrite toroid core. 3.6dB/100m@4MH In its simplest form there are two windings where the impedance are as in equation 33.1. 5.6dB/100m@8MHz 6.3dB/100m@10MHz (33.1) 9.1dB/100m@16MHz NE Crosstalk 50dB/100m@1MH 40dB/100m@16MH where Z, is the impedance of the first winding n1 is the number of turns on the first winding Outer Diameter Z2 is the impedance of the second winding Conductor Diameter 0.5mm n2 is the number of turns on the second winding More complex impedance matching can be achieved by wiring additional windings in series with these windings SO that their mutual inductance adds to or substracts from the total inductance. The equations of the resultant inductance formed by connecting 33.3.1 Baluns two mutually coupled windings in series are shown in Equations 33.2 and 33.3, where the mutual inductances add in one case and Baluns are impedance matching and circuit balancing devices pri- oppose in the other. marily consisting of a ferrite toroidal transformer. They provide the interface between one cable media and another but present the L =L, +L2+2M series aiding (33.2) characteristic impedance of the original media to the transmitting and receiving equipment. For example, if an office has been wired L =L, +L2 - 2M series opposing (33.3) in unshielded twisted pair (UTP) but the tenant requires to run a coax service, a balun at both ends of the UTP line will give it Where L is the resultant inductance characteristics similar to coax. L, is the inductance of winding 1 The word BAL-UN is an amalgamation of the abbreviations BALanced and UNbalanced. Baluns are fitted at both ends of the L2 is the inductance of winding 2 M is the mutual inductance between the two winding. UTP cable, at the equipment end and terminal end. There are a range of baluns to correct for each type of media. At the terminal end there are three options to where baluns are located: 33.4 Network topology 1. Baluns in adaptors at terminal end. The topology of a ne