Cisco Technology, Inc.

Jim C Chiappe

Phillip S Ting

Hsing-Sheng Liang

Saeed Seyed

Mehran Ataee

Meilissa R Lum

Sridevi Iyengar

Dean Wood

Methods and apparatus for shielding an object from relative high electromagnetic radio frequencies while allowing airflow to pass to and from the object are disclosed. According to one aspect of the present invention, a shield arrangement that shields a chassis includes at least a first plane and a second plane. The first plane has a thickness and defines a first plurality of openings that include a first opening and a second opening that are separated by at least a distance that is a function of the thickness. The second plane defines at least a third opening, and is approximately parallel to the first plane. The second plane is spaced apart from the first plane by a spacing that is a function of at least the thickness.

Providing airflow to an electronics enclosure while providing protection and shielding against electromagnetic interference

A panel member attaches to a frame that supports electronic circuitry. The panel member includes a mounting portion configured to mount to the frame, and a face portion coupled to the mounting portion. The face portion defines a plane and multiple openings within the plane. The panel member further includes multiple brimmed portions coupled to the face portion. Each brimmed portion (i) extends around an opening defined by the face portion and (ii) projects from that opening in a direction which is away from the plane. The use of such a panel member provides improved airflow and stagnation pressure as well as robust electromagnetic interference protection.

Techniques for providing ventilation and EMI shielding to electronic circuitry using a panel member with brimmed holes

A common mode termination includes a shielded connector, a receive section and a transmit section, each section comprising an isolation transformer, a common mode transformer, a reference autotransformer, and an AC shield return. Each transmit section reference autotransformer and receive section reference autotransformer has a center tap for the application of a bias voltage and a bias voltage return. The bias voltage is fed through a common mode transformer, and the resultant common mode termination reduces the conduction of EMI from the serdes coupled to the common mode termination to cables connected to the connector. This common mode termination also provides a reference termination for the copper twisted pair cable and reduces resonances on the cable. Finally, this termination also provides filtering on the DC power source wires and improves noise immunity from transients coupled onto the twisted pair cable into the system.

Common mode termination

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Walnut Creek, CA, United States of America

Jim C Chiappe