Other

Isidor Straus

Glen R Dash

A ferrite sleeve or bead either in round configuration or square or rectangular configuration and either whole or split is employed as a means for reducing radiation emissions associated with a computer or the like data processing system. The ferrite system is disposed over the I/O cable either over a segment thereof or along the length thereof and in one embodiment is in the form of one or more ferrite beads that may be associated with wires internal to the data processing system. In a further embodiment of the invention the ferrite sleeve may be replaced by an equivalent circuit network comprising a parallel inductor and resistor in which the inductor is wound over a resistive core. The ferrite sleeve is dimensioned to have an impedance at the operating frequency greater than the signal cable conductor means radiation resistance, thus establishing a voltage divider circuit between the impedance of the ferrite sleeve and the radiation resistance, to thus reduce emissions due in particular to common mode noise.

Electromagnetic emission control system

A reference antenna construction preferably employing a biconical antenna in combination with a balanced to unbalanced transformer or balun adapted to provide proper matching and operation over a broad frequency range. The reference antenna is used to calibrate other antennas. A ferrite sleeve is preferably used over the balun to reduce unbalanced currents flowing in the shield and to improve performance. A tool is described that allows fast and accurate construction of the balun by providing precise severing of the center conductor.

Reference antennas for emission detection

A circuit is described for substantially reducing the level of radiation from another circuit such as a clock circuit that might be used in a computing device. By maintaining the current drawn by the clock driver from the power supply at a constant level, the amount of radiation is lowered. If all currents drawn can be controlled so as not to change as the clocking occurs, then radiation from the clock is essentially eliminated.

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Wayland, MA, United States of America

Isidor Straus