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Ein vektorieller Netzwerkanalysator für den Frequenzbereich 0 - 400 MHz zum Eigenbau

A Homebrew Vector Network Analyzer for AF to UHF

last updated: January 21st, 2009


Software Downloads:

English article  "Low Budget Vector Network Analyzer from AF to UHF" from Mar/Apr 2007 issue and "Letter to the Editor" from May/Jun 2007 issue of the American Radio Relay League QEX magazine with kind permission of the ARRL.
German article published in the CQ DL ( Magazine of the German Amateur Radio Club DARC) in volumes 3,4,5/2007. Downloads with kind permission of CQ DL:     part1, part2, part3

After appearance of the first part of my German article in CQ DL I have received many positive feedbacks (THANKS A LOT!!!) and also questions on availability of kits and on measurement accuracy of the setup. Therefore see below information on these points.

Accuracy Tests:

Below I have measured my calibration standards after calibration in the frequency range 10kHz...100MHz to give a hint on accuracy and dynamic range. Measurements have been performed with an on board 16 bit sound card on my IBM R52 ThinkPad.

S21 Isolation measurement indicating the expected 90dB dynamic range (16 bit AD):

Open (black) Short (red) and Load (blue) calibraion standards from 10kHz to 100MHz:

Return loss of Load calibration standard indicating about 80dB dynamic range on S11 measurement:

Thru calibration standard measured with high resolution indicating an accuracy of about +-0.01dB and +-0.1°:


A few hints to use the software

You use this software at your own risk! I'm not responsible for any damage that may come from its usage!

The VNWA software can also be used without VNWA hardware connected to visualize and analyze Touchstone S-parameter files and to run matching simulations on these. If so, be aware that data might be written to the parallel port so damage could be done to hardware connected to it!
To import s1p or s2p files select >file >import ... . S21 is stored in Mem1, S22 in Mem2. Select traces and display types, colors ... by >measure >display or by left or right clicking the labels on the left and on the bottom. Try also double-clicking them. Try dragging the labels on the right! Try pointing to the labels left and right and turning the mouse-wheel!
Use >tools >matching tool to recalculate loaded S-parameters to source and load conditions other than 50 Ohms. 
Have fun!

Minimum requirements:

Connection Parallel Printer Port to VNWA:

 D0:  Data DDS1
 D1:  Clock DDS1+2
 D2:  Set DDS1+2
 D3:  Data DDS2
 D4:  switch control S11/S21
 D5:  switch high/low Tx power


Important: The software can only be run in an account with administrative rights! Otherwise, it will crash quite ungracefully while trying to mount the parallel port driver!


  1. Unzip and copy the two files (software and parallel port driver) to any directory.
  2. Simply run VNWA.exe - You should automatically enter hardware setup

Here the PC hardware can be tested (top) and the time calibration can be performed. Note the status line on the bottom.
If you have no VNWA connected just close this window.

This is it!

Complete Measurement Setup

The Analyzer

Measurements of a 10.7 MHz Crystal Filter and Matching Simulation

The red reference curve was measured with a HP8753C.

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