Why are micro-ethernet adapters not a thing? A physical adapter that takes our thirty year old standard sized RJ45 jack on one side and and plugs into a TabletPC on the other.

Every other form of high speed communications has already shrunk to much smaller than the RJ45 form factor. All of the following can achieve speeds much faster than 1Gbps but have much smaller sized physical connections:

  1. miniUSB
  2. microUSB
  3. USB-C
  4. displayPort
  5. microDisplayPort
  6. miniHDMI
  7. microHDMI
  8. miniSAS - SCSI Attached Storage

So how were these other technologies able to shrink to small connector size but at faster speeds? Yes, ethernet works over distances of 100meters whereas none of the above except miniSAS work directly over 5meters, but of course MiniSAS is much much faster. Certainly engineering and modern manufacturing could make a physical adapter to reduce the physical size down to easily fit in a modern laptop, not cause NEXT and still not slow the speed down that much? The conductors have to be closer together, so microRJ45 would need to mitigate Near End CrossTalk or NEXT. Could that be achieved at manufacturing by increasing the twists-per-inch inside the adapter?

Please do not answer with Ethernet-to-USB dongles as they are insecure, severely limited for PXE, have driver issues, and unstable.

Thirty years from now, will the RJ45 ethernet jack on PCs be antiquated? Will we chatting about the old days of RJ45 wired ethernet like we talk about token-ring and dot matrix printers today?

I have asked this same question in electronics, physics and Network Engineering, but it was rejected in every single one. They suggested to ask in retro computing.

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    Retro computing talks about the past not predicts the future... – Solar Mike Jun 12 '20 at 20:19
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    I don't think the size of the RJ45 connector has anything to do with Ethernet speed. the 1Gbps limit comes from the capacitance of up to 100 meters of twisted pair wiring, increasing speed requires lowering the capacitance, which is easiest to do by shortening cable lengths to a few feet or less. I'm not an EE but I believe the capacitance contribution of the RJ45 connector is negligible. – Ken Gober Jun 12 '20 at 20:52
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    To make this just a little retrocomputing-relevant: There were small form factor Ethernet connectors for PCMCIA Ethernet cards (think mid-to-late 90s). They connected the card to an external dongle, which in turn housed the BNC and/or RJ45 connector (and maybe some physical layer stuff). – Michael Graf Jun 12 '20 at 23:15
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    I think the answer to the "why not" question is that there was no need, as Wifi provides an adequate replacement for small devices, and large devices have no problem with RJ45. – Michael Graf Jun 12 '20 at 23:17
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    Since this is retrocomputing: RJ45? Call that an ethernet connector? This is an Ethernet connector! – another-dave Jun 13 '20 at 0:01