This webpage contains description of and links to documents related to the usage of the wonderfull Vector Network Analyzer VNWA2, VNWA3 and VNWA3E designet by DG8SAQ Tom Baier to purchase from Jan Verduyn via the webshop SDR-KIT www.sdr-kits.net Find also a Yahoo Forum devoted to VNWA "lover's" at the link: http://groups.yahoo.com/group/VNWA/
During HAMRADIO 2012, 2013 and 2014 in Friedrichhafen DG8SAQ Tom Baier presented the VNWA
which I recorded and published on YouTube in various languages. So far for 2012 in German, English, Danish
and Japanese. For 2013 in German and English and for 2014 soon to be published.
A direct downlaod from my homepage http://www.hamcom.dk/VNWA (where you are now!!) is also possible. DG8SAQ's German Powerpoint presentation was translated to English, Danish and Japanese, and available as pdf files, as well an English text document, also as a pdf file, with transcript of the soundtrack, so a detailed study can be performed offline.
1A. Rosenberger Cal Standard rev3.pdf (now obselete) Updated version per December 2013, with minor changes to the calibration settings, for Female Female Thru/Open adaptor and added data for a Male Male Adaptor recently introduced for "SDR-Kits Calibration Kit of Rosenberger parts"
1B. Rosenberger Cal standards rev2.pdf (now obselete) This document explains how the various parameters must be entered in the VNWA Softwaren, to obtain a quality calibrering, by using adptors from Rosenberger forming a Female Short, Open og Load (SOL) calibration kit, which includes a Female-Female adaptor used as Open standard and for the Through (T) calibration. The complette calibration is called a SOLT calibration. Existing data for these Rosenberger female parts considered fairly accurate, Thus adapted as "a Master kit" for " the VNWA world" when price taken into considration, as a professionelt calbrations kit is extreme expensive. Rosenberger SOLT parts can be purchased in small quantities by German bodies directly from Customer Service at Rosenberger Hochfrequenztechnik GmbH & Co. KG, but " non German bodies" must contact national distributors, which request volume orders (e.g. 10 pc. of each type) and quite elevated prices. SDR-Kits is the place to purchase a female and now also a male calibration kit, at fair prices
2. Amphenol Connex Cal standards rev3.pdf (now obselete) Further to acquire is an Amphenol Connex (SOLT) Calibration kit, both as Male og Female versions, available from the SDR-Kits webshop. In the calibration sheet you find the setting to enter in the VNWA software, to obtain a quality calibration quite identical to the performance for the Rosenberger kit up to 500MHz, and with fairly good result up to the limit of 1.3GHz for the VNWA, provided the given data used.
3. What in particular to mention for Rosenberger Cal standards Rev3 and Amphenol Connecx Cal standards rev3 both now also in rev4? When calibrating you can be ensured a quality calibration, provided using the data found in the calibration sheets, to be entered in the calibration settings of the VNWA software. When meauring S11 og S22 data, for a test object often called a DUT (Device Under Test), you are measuring impedances, and the SOL calibration done, using a Short, Open and Load calibration standard. Furthermore, when measuring transmission responces, e.g. a lowpass filter, a further T (Through) calibration must be performed, where the VNWA TX port (which is the one used for SOL calibration) must be connected to the VNWA RX port. Normally two male male test cables are connected to the TX og RX ports, and during the S21/S12 (Through) calibration, the two test cables connected via a female female Thru adaptor, creating the signal part between TX and RX port. The female-female adaptor is removed after the Thru calibration and the extra delay thus introduced during the Thru calibration must be compensated, to ensure phase sync between reflection (S11/S22) and transmission (S21/S12) measurements, . From VNWA software version 36.2.xm onward this compensation is taken care of by entering the delay of the thru adaptor in the Calibration Settings.
4. Instruction for use of SMA Load Testbox.pdf An important detail to note is that for any type of calibration load, its resistance must be known. Variations of these load resistances are typical up to 1,5 ohm. I have designed a simple 4 point test equipment, for accurate measurement of a loads resistance, with 0.1% accuracy. (A newer version with 0.01% accuracy made). For those interested contact med for schematic and PCB layout.
5. How to measure on SOL calibration kits_REV1.pdf As supplement to above 4 documents, the document How to measure on SOL calibrations kits_REV1.pdf is of interest to study. Although of age, it is still valid and you can find stock numbers for the Rosenberger Female SOLT Calibration kit, and study the technical published data. In the document I also explains how the data used in the Rosenberger Cal standards rev1.pdf is calculated, which can be used for other adaptors. In the document is also to find a number of measurements for a homemade N connector Short, Open and Load calibration kit. However a far better document is made and to be released late 2014, which can provide N male and female calibration standards of high performance and easy to reproduce.
6. T-Check testing Rohde & Schwarz has developed a mathematic model and software, which can test the quality of a VNWA SOLT (Short Open Load Through) calibration. However it is quite simple to enter as a published text string into a VNWA "Custom Trace" (a VNWA feature/function) and perform a forward og reverse measurement, where the S21 Thru Female-Female adaptor is exchanged with a Female-Male-Female T adaptor, where the "third leg" is fitted with a 50 ohm load e.g. the one used during calibration. The theoretical background can be found by downloading the Rohde & Schwarz T-Check software, which I have been granted permission to publish. It is a pdf file and a zip file accessable by the link below.
Tutorial on correct connection for VNWA2 or VNWA3 to the PC USB ports. It has been experianced that the USB port can create some trouble when performing AM and FM modulation. If the modulation is noisy, then an internal USB port is shared as the VNWA2 or VNWA2 then is using the internal shared USB Hub.
This web page might now and then be updated when I have written new articles, or added old articles of general interest. Be wellcome to contct me by email kurt@hamcom.dk Besides the VNWA software can be used without being the owner of a VNWA. In particular the help section /help file is a gold mine. The link to the software is: http://sdr-kits.net/DG8SAQ/VNWA-installer.exe
