I agree: a cable only radiates what it is fed. If it is properly
terminated, circuit-wise and shielding-wise, it's being fed too
lavishly. In this case, the good shielding indicates high common-mode
current in the shield. It could be interesting to measure the emissions
with a cable shield connected at the sending end only. This obviously
stops the CM current, but the CM then appears as voltage on the shield.
Interpreting the results requires thought; one deduction might be the
internal impedance of the source of the CM, leading to identifying the
source.
On 2025-05-15 16:55, Ted Eckert wrote:
Hi Peter,
The last time I had a similar problem with HDMI, the issue wasn't the
cable. The host device had an improper PCB layout for the HDMI
signals. Paired signal traces weren't properly matched leading to
extra noise. Is your issue with just one host product or with multiple
products?
Ted Eckert
The opinions expressed are my own and do not necessarily reflect those
of my employer.
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*From:* [email protected]
<[email protected]>
*Sent:* Thursday, May 15, 2025 8:43 AM
*To:* [email protected] <[email protected]>
*Subject:* [EXTERNAL] [PSES] HDMI cable emissions
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Hello group,
I am working on a HDMI cable where it does not pass radiated emissions
with good margin. I have great braid coverage and have soldered the
braid to the connector shell and have fully sealed and covered it with
copper tape. Is there anything else that I need to do? My issue is
mainly at below GHz when I use 1080P resolution.
Thank you
Peter
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