On Wed, 18 Sep 2019 at 19:54, <erik@...> wrote:
Ah. Correct. He did not refer to the model structure but used direct
numbers in the code.
That
c = 50e-15;
needs to be replaced by a function
C(f)=C0 e-15 + C1 e-27 f + C2 e-36 f^2 + C3 e-45 f^3
where C is in farads, and f in Hz.
That's the format used by all HP/Agilent cal kits, which are by far the
most common on the market. Copper Mountain use the same, and others use
something similar.
where for a constant 50 fF, it would be
C0=50, C1=C2=C3=0.
The values of all the Keysight cal kits can be found at
Many kits have different values for male and female parts.
The very common 85033D or 85033E (3.5 mm kits) have identical values for
male and female, but the common 85032B N cal kit does not, and neither does
my 85054B N cal kit. Obviously for APC7 kits it is irrelevant.
It would be good if the user could define a few cal kits, and name them.
For example, the kits I have are
* 85050B (APC7)
* 85052B (3.5 mm)
* 85054B (N)
* 85038A (7-16)
* 85039B (F)
None of those kits are going to be common on the use market at a price hams
are likely to be able to afford, although the 85052B does share the same
coefficients as the 85033D and 85033E, which are quite common. The 85050B
(APC7) can often be found cheaply, but it is not a kit most people are
going to want.
I personally intend building cal kits for every connector I can think of
into a box that the NanoVNA fits in. That's partially out of the
practicalities of never have to carry a cal kit, but partly out of the fact
that I can do it.
--
Dr David Kirkby Ph.D C.Eng MIET
Kirkby Microwave Ltd
Registered office: Stokes Hall Lodge, Burnham Rd, Althorne, CHELMSFORD,
Essex, CM3 6DT, United Kingdom.
Registered in England and Wales as company number 08914892
Tel 01621-680100 / +44 1621-680100
