Sunday, April 28, 2019

Could we shrink the RJ45 plug?

Hi all -- It's a bit of a blue sky question, but could the RJ45 plug be shrunk to something half as big or less? It's not clear to me why it needs to be so bulky, and its bulkiness has evicted it from lots of laptops these days (and streaming devices, mostly the sticks like the Fire stick, Chromecast, etc.)

When I dug into this a couple of years ago, I found the Nu45 proposal by Broadcom engineer Michael Johas Teener. It's remarkably similar to USB-C in appearance and design, but it was before USB-C. (And he thinks the similarity is "one hell of a coincidence", meaning the USB-C designers had seen his Nu45 work.)

When I look at an RJ45 plug, something that strikes me are the tall copper blades that shoot up from the contacts. They seem to go maybe three fourths of the way up the plug. The remaining height is just plastic and the latching mechanism. I'm not an electrical engineer, so I don't know how necessary those tall contact blades are.

One thing that stands out for me about Cat cables and their connectors is range. Cat cables have extraordinary range, and I don't know which aspects of the connector design, if any, are important to achieving such range. By contrast, USB has extremely short range – even USB-C. For the max data rates, I think USB-C can only go up to a couple of meters or so, maybe 5. I'm not clear on whether Nu45 could retain Cat cables' normal range, since USB-C can't and they're so physically similar.

Does anyone know if the tall blades in RJ45 plugs are essential to Cat cables' range?

One example of an actual product that offers ethernet with much smaller connectors are TE's Mini I/O connectors, which they say supports Cat6a performance. I'm not sure what impact they have on range.

Have you seen any other designs for smaller ethernet plugs?



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