John Woodgate wrote:
I read in sci.electronics.design that Ian White, G3SEK
wrote (in ) about
'Measuring radiation resistance', on Mon, 8 Dec 2003:
I'm looking forward
to making some outdoor antenna measurements using the new N2PK vector
network analyser

Is N2PK a call-sign? Are there any details of this analyser on the
Internet?

Yes; it belongs to Paul Kiciak.

And yes -

The original website URL is:

Â*Â* http://users.adelphia.net/~n2pk/

Â*Â* There is also a mirrored website at:

Â*Â* http://www.qsl.net/n2pk/



Very briefly, it's a 0.05-60MHz VNA based on a DDS signal source feeding
the Device Under Test. Output from the DUT goes to a 'zero IF' detector
(multiplicative mixer) that converts to a DC signal level, which in turn
goes to an ADC.

The local oscillator for the detector is a second identical DDS,
programmed to the same frequency. Phase information is obtained by
making two sequential measurements, one with the LO at the same phase as
the signal source, and the second with the LO switched to 90deg.

Control is via the PC parallel port, which also accepts the signal level
data from the ADC. The support software includes full calibration
facilities (open/through for transmission measurements, and
open/short/load for reflection measurements with a bridge attachment).

For such a simple concept, the accuracy is astonishingly high,
approaching that of a commercial VNA. Paul Kiciak has investigated these
issues very thoroughly indeed, and the results are fully documented.

Everything is on the website, including full constructional information,
board layouts, software and extremely detailed documentation.


--
73 from Ian G3SEK 'In Practice' columnist for RadCom (RSGB)
Editor, 'The VHF/UHF DX Book'
http://www.ifwtech.co.uk/g3sek