Crosstalk attenuation characteristics between shielded balanced pairs

Abstract Future telecommunication networks will be digitalized and widebanded. The crosstalk between telecommunication lines will be a problem when bilateral signals are transmitted concurrently through a balanced pair cable. A study to suppress this crosstalk is being conducted on a balanced multipair cable with internal shielding for proper units, hereinafter referred to as a shielded balanced pair cable. Theoretical equations are needed to represent the crosstalk attenuation characteristics between shielded balanced pairs for the purpose of designing shield structures for such cable. Hitherto, no equation has been derived pertaining to the amount of crosstalk attenuation between shielded pairs applicable to the design of shield structures. In this paper, shielded balanced pair cables are divided largely into unit‐shielded types and screen‐shielded types. Theoretical equations are derived pertaining to the amount of crosstalk between shielded balanced pairs with consideration of both direct and indirect crosstalk paths. The correspondence to measurements permits design of shield structures by confirming the adequacy of the theoretical equations. In addition, it is established that both direct and indirect crosstalk have dominant frequency ranges considering these frequency characteristics. The electrostatic unbalanced capacitance is also presented for wire shielding within a required amount of crosstalk attenuation.