Electromagnetic interference is one of the factors that limits range and data rate in data communication systems. In order to reduce interference from ambient electromagnetic environment, data communication systems typically use balanced transmission lines.
In balanced data communication systems a signal appears as the differential mode (DM) current component and interference appears as the common mode (CM) current component. The interference may result from man-made and natural ambient electromagnetic fields, crosstalk, imbalances and mismatching of impedances for DM and CM waves propagating along a transmission line. Reduction or elimination of interference thus requires rejection of the CM component.
Some aspects of technologies and related art that may be useful in understanding the present invention are described in the following publications:
a data sheet of MIDCOM Corporation, of 1056 N. Tustin Ave, Anaheim, Calif. 92807, USA, mod2RJ45tm, rev.011204, which demonstrates a typical 10/100 BaseT Integrated RJ45 connector;
a data sheet of XMULTIPLE USA Ltd., of 1420 Los Angeles Avenue, Suite G-Simi Valley, Calif. 93065 USA, Part No. XRJH-12-01-8-C-Z-771 Drawing, dated 30 Jun. 2003, which demonstrates a typical 1000Base-T RJ45 connector;
U.S. Pat. No. 5,594,397 to Uchikoba et al, which describes an electronic filtering part using a material with microwave absorbing properties;
U.S. Pat. No. 5,847,628 to Uchikoba et al, which describes an electronic part using a material with microwave absorbing properties;
U.S. Pat. No. 6,603,080 to Jensen, which describes a circuit board having ferrite powder containing layer;
U.S. Pat. No. 5,756,932 to Barnett, which describes a signal distribution structure having lossy insulator;
U.S. Pat. No. 4,301,428 to Mayer, which describes a radio frequency interference suppressor cable having resistive conductor and lossy magnetic absorbing material;
U.S. Pat. No. 4,383,225 to Mayer, which describes cables with high immunity to electromagnetic pulses (EMP);
U.S. Pat. No. 4,506,235 to Mayer, which describes an EMI Protected cable, with controlled symmetrical/asymmetrical mode attenuation;
U.S. Pat. No. 4,347,487 to Martin, which describes a high frequency attenuation cable; and
U.S. Pat. No. 6,553,910 to Fogle, Jr., which describes hermetically-sealed electrically-absorptive low-pass radio frequency filters and electro-magnetically lossy ceramic materials for said filters.
The disclosures of all references mentioned above and throughout the present specification, as well as the disclosures of all references mentioned in those references, are hereby incorporated herein by reference.