[time-nuts] Thermal effects on cables

[Tim Shoppa]

Dave, the typical spec sheet for VNA cables have a very restricted "lab
temperature" range specified. For example 23C +/- 5C.

There's a very nice graph showing effect of flexure on phase stability in
Fig 2 of this spec sheet:
https://www.gore.com/sites/g/files/ypyipe116/files/2016-07/GMCA-0224-DAT-US-MAY16_e.pdf

Funny how people always want to put the words "dielectric" and "constant"
right next to each other but we know it isn't constant :-)

Tim N3QE

On Mon, Jan 23, 2017 at 8:26 AM, Dr. David Kirkby (Kirkby Microwave Ltd) <
drkirkby at kirkbymicrowave.co.uk> wrote:

> On 13 January 2017 at 06:52, Ole Petter Ronningen <opronningen at gmail.com>
> wrote:
>
> > Hi, all
> >
> > The question of phase shifts in cables pops up every now and then on this
> > list - I stumbled across a good table of measured phase shifts with
> > temperature in different cable types in this paper:
> > http://www.ira.inaf.it/eratec/gothenburg/presentations/ERATEC_2014_
> > PresentationWSchaefer.pdf
> > that I though would be of interest to others.
> >
> >
> I've like to know how VNA cables compare. They are expensive enough - a
> couple of cables around 600 mm long (24") for my VNA are over $5000. They
> are much larger diameter than normal cables, but much more flexible too.
> The construction is obviously very different. Since mine are designed for
> use to 26.5 GHz, the internal diameter of the outer conductor can be no
> more than a couple of mm, yet the overall cable has a diameter of about 15
> mm.
>
> Dave
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