Flat Ethernet cables - what is that about?

[David]

Back in ancient history network cables had to be twisted to stop
interference.
I think.

Now Ethernet cables are sometimes flat.
Is this a new thing?
Is it because both ends can cope with more interference?

Just idly puzzling.

Cheers



Dave R

[Andy Burns]

Post by David
Back in ancient history network cables had to be twisted to stop
interference.
I think.
Now Ethernet cables are sometimes flat.

Doesn't mean they're not twisted pair ...

[Abandoned Trolley]

Post by David
Back in ancient history network cables had to be twisted to stop
interference.
I think.
Now Ethernet cables are sometimes flat.
Is this a new thing?
Is it because both ends can cope with more interference?
Just idly puzzling.
Cheers

I had a NAS box about 15 years ago (possibly called a Buffalo
LinkStation) which came with a flat Ethernet cable - so its definitely
not a "new" thing

[Jeff Gaines]

Post by David
Back in ancient history network cables had to be twisted to stop
interference.
I think.
Now Ethernet cables are sometimes flat.
Is this a new thing?
Is it because both ends can cope with more interference?
Just idly puzzling.
Cheers

I had a NAS box about 15 years ago (possibly called a Buffalo LinkStation)
which came with a flat Ethernet cable - so its definitely not a "new"
thing

My Buffalo Terastation introduced me to a flat Ethernet cable as well!

[Theo]

Post by David
Back in ancient history network cables had to be twisted to stop
interference.
I think.
Now Ethernet cables are sometimes flat.
Is this a new thing?
Is it because both ends can cope with more interference?
Just idly puzzling.

Pairs are run close together to minimise the area of the inductive loop the
signal current flows around (transmitter+ => wire+ => receiver => wire- =>
transmitter-)

In an external magnetic field, the induced curent is proportional to the
loop area. Make the loop as small as possible => small induced current =>
minising interference from induction

Twisted pairs are a way to achieve a very small loop area - the tighter the
twist the smaller the loop. They also take out imbalances, eg one wire
being closer to the edge of the cable than the other.

Some flat cables have the pairs twisted, so all is fine.

On those where the pairs aren't twisted, they're run in parallel. The loop
area is still kept small, but there's a risk of unbalance, eg capacitive
crosstalk from wires in adjacent pairs. To remedy this they are kept short
(capacitance is proportional to area of the plates - length of adjacent
wires in this case). They are just patch cables, and not used for wiring up
an office block.

Theo