VNA

N

njkenworthy

Guest
Hi
Have been creating a VNA using an HP 3350, 10-2400 Mhz and some trick
Analoge Devices` IC s plus a PIC and Visual Basic..........about 12 months
so far.

Have learn`t a lot on way but much to learn.

Q. How do normal VNAs display their data?
Q. Do typical VNAs measure power information and compute voltage ....and
thus voltage S-params
Q.Anyone ever tried to accomplish Vector Error Correction ? Not overly hard
, but the combinations required for a full set of S-Params
are......intimidating.
Q. My SMA directional couplers only show an "uncorrected" directivity of
about 10 dB..this is not great precision......what can I expect for Ł50.00
outlay.


Before you respond...I have most HP/Agilent App Notes and and am trying to
absorb.

Any help welcome and welcome discussion
 
njkenworthy wrote:
Hi
Have been creating a VNA using an HP 3350, 10-2400 Mhz and some trick
Analoge Devices` IC s plus a PIC and Visual Basic..........about 12 months
so far.

Have learn`t a lot on way but much to learn.

Q. How do normal VNAs display their data?
Q. Do typical VNAs measure power information and compute voltage ....and
thus voltage S-params
Q.Anyone ever tried to accomplish Vector Error Correction ? Not overly hard
, but the combinations required for a full set of S-Params
are......intimidating.
Q. My SMA directional couplers only show an "uncorrected" directivity of
about 10 dB..this is not great precision......what can I expect for Ł50.00
outlay.


Before you respond...I have most HP/Agilent App Notes and and am trying to
absorb.

Any help welcome and welcome discussion


Today VNA's display the data any way you want. A good place to see an
Click to expand...
application which you can download. Is on Agilent's site the application
is AppCad. The new bit everything S-parameters basically does about what
a VNA does to display data.

Current VNA's basically calculate anything you would conceivably want.
But remember S-parameters are basically small signal power parameters at
50 or 75 ohms. Having said that you will find waveguide add-ons that
take you out into millimeter territory for current generation machines
and into high power microwave frequencys (like watts into a device at 6
Ghz).

Vector error correction is basically just mathematical correction. For a
home based project a piece of software which you should try to get your
hands on was written by Rutledge and co. (at Caltech) which basically
did your project using a PC, an HP8410 and an 8350. Another resource
available is the Puff software from Caltech (now you have to buy the book)

Your directional couplers just are to bad to cut the mustard.

The goal you have set yourself on is a long and difficult path.

Good luck
and Good management.

Andrew
 
many thanks for your response aqnd the two NEW leads offered...I have
downloaded the AppCad thing from Agilent and will begin to experiment . What
I wuld love to do is take some of the code and paste it in to my App thus
saving a tonne of time ...c`est la vie.
I checked the Caltek site and V2.1 of thier software seems to be abt $10.00
dollars.
I understand that my project is a big bite, but some people can only learn
by going over the whole ground themselves.......me.
I made a typo error..my sig gen is also an 8350.....I must get hold of the
man at Caltech.....

Many thanks for your help.

Nick

"Andrew Tweddle" <sarason@alphalink.com.au> wrote in message
news:3ff0f149@news.alphalink.com.au...
njkenworthy wrote:
Hi
Have been creating a VNA using an HP 3350, 10-2400 Mhz and some trick
Analoge Devices` IC s plus a PIC and Visual Basic..........about 12
months
so far.

Have learn`t a lot on way but much to learn.

Q. How do normal VNAs display their data?
Q. Do typical VNAs measure power information and compute voltage ....and
thus voltage S-params
Q.Anyone ever tried to accomplish Vector Error Correction ? Not overly
hard
, but the combinations required for a full set of S-Params
are......intimidating.
Q. My SMA directional couplers only show an "uncorrected" directivity
of
about 10 dB..this is not great precision......what can I expect for
Ł50.00
outlay.


Before you respond...I have most HP/Agilent App Notes and and am trying
to
absorb.

Any help welcome and welcome discussion


Today VNA's display the data any way you want. A good place to see an
application which you can download. Is on Agilent's site the application
is AppCad. The new bit everything S-parameters basically does about what
a VNA does to display data.

Current VNA's basically calculate anything you would conceivably want.
But remember S-parameters are basically small signal power parameters at
50 or 75 ohms. Having said that you will find waveguide add-ons that
take you out into millimeter territory for current generation machines
and into high power microwave frequencys (like watts into a device at 6
Ghz).

Vector error correction is basically just mathematical correction. For a
home based project a piece of software which you should try to get your
hands on was written by Rutledge and co. (at Caltech) which basically
did your project using a PC, an HP8410 and an 8350. Another resource
available is the Puff software from Caltech (now you have to buy the book)

Your directional couplers just are to bad to cut the mustard.

The goal you have set yourself on is a long and difficult path.

Good luck
and Good management.

Andrew
Click to expand...
 
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