Experiments with the DG8SAQ VNWA and the SDR-Kits Test ...

1 DG8 SAQ VNWAT utorialDG8 SAQ vnwa TutorialExperiments with the DG8 SAQ vnwa andtheSDRKits Test BoardandtheSDR-Kits Test BoardTom BAIERTo m BAIERDG8 SAQThis is an excerpt from my Ham Radio 2013 presentation which has been slightly extended (slides 6 20 and 21 added)been slightly extended (slides 6, 20 and 21 added). BoardforHF ExperimentsTest Board forHF ExperimentsCalibrationShCalibrationStand ards:Short:Load=47 :Load= 47 : :Open = Load -Resistor without SOL-Calibration? Works, becauseVNWA TXandRXVNWA TX andRX port impedancesareexactly50 areexactly50 . onlyThru onlyThrucalibrationrequired!Zx= 47 yield 3,4 dBinsertionlossrequired! Load -Resistor in Transmission (=S21-Measurement)Only Thru calibrationrequiredMeasurement: ResistorbetweenrequiredResistorbetweenTX and Load -ResistorResult = 46,6 ntamissioondatinductive parttransmeflectionverttato with Custom TraceCondataReflectionDatavsTransmission DataReflectionData vs.

2 Transmission Datanormalizednormalizedimpedance:!Z!50x Zz 50 21112( )SstS 1111zS 2122S 21112( )SstS1z 212z 11212( )StsS conversions can be performed with vnwa Custom Calibration Standard Model:Only measured Load- Measurement (S11) of a1 nF Capacitor|S|C|S11| ResonanceduetoESRlcapacitivedue tocomponentwiresESR = almost total power, |S11| 0 dBModelling of Measurement Result in vnwa using Custom-TraceIdtRfl iffi itImpedancetoReflecion coefficient0,984 nF9,3 nH0,22 ,,,einfaches ModellThe Modelisquiteaccurate!The Model isquiteaccurate!ktive ! Port Measurement of a 12 kHz Band Pass Filter S-Parameters applicable to lowfrequenciesaswellfrequenciesaswell. The vnwa too! vnwa SettingsforlowFrequenciesSpecial vnwa Settings forlowFrequenciesLowest sample rate 300 Hz Nyquistlimit150 HzIF must be within Codec frequencyrange Nyquistlimit150 Hz Measurements down to 150 Hzpossiblefrequencyrange(20 ) 150 Hz possibleSOLT-Calibrationfor2-PortMeasure mentsSOLTC alibrationfor2 Port MeasurementsTXTXRXS hortOpen : Steep Skirt Filters require Time tosettle to changing Stimulus!

3 5 s sweep time0,3 s sweep time Port Measurement of a 12 kHz Band Pass FilterWe need to measure all four S-parameters(S11,S21,S12,S22).. (S11, S21, S12, S22) ..Two Port Measurement of a 12 kHz Band Pass Filter: Forward MeasurementTX12 , S21measuredTwo Port Measurement of a 12 kHz Band Pass Filter: Reverse MeasurementTXTX21 , S22measuredWhat are measured 2-Port S-Parameters good for?Optimum Match? Matching Tool (1)Allowstorecalculate2-portAllowstoreca lculate2port S-parameters to source andldiddifftloadimpedancesdifferent from 50 Ohms! Matching Tool (2)Complex conjugate of Complex conjugate of pjgsourceimpedance=pjgloadimpedance==fil ter inputimpedance=filter Analysis with vnwa Matching ToolOptimum: Zin= Zout= 610 usingResistors50 560 610 + 560 = 610 MatchworksexceptforincreasedLossMatch worksexceptforincreasedLossSil t dithSimulatedwithMatching Tool dBMeasured withresistive of two 560 Resistors in Signal Path: vnwa Complex Calculator21 7 dB additionalattenuation ,7 dB additional attenuation This can also be properly simulated!

4 Simulation Tool QUCShtt //ft/ Universal circuit simulatorF Free No restrictionsEt Easy touse Grafics and data export in QUCSM easuredSParameters in qucs measuredS-parameterspfrom s2p- in QUCSM atchingSimulation in QUCSS tandard diagrammoutput a bit strange Export simulation qucs -Simulation vs. MeasurementdithiltdmeasuerdwithVNWA simulatedwith QUCSPERFECT!PERFECT! Filter Design Software (1): Elsie forLC-Filters LC-Filter DesignerandAnalyzerLCFilter Designer andAnalyzer Student version restricted to 7 dipols Numericalsimulationresultsexporteasilyto Numericalsimulationresultsexporteasilyto s2p-file! Filter Design Software (2): Dishal forCrystal Filters Crystal filter designer and analyzer Simulateswithoutcrystallosses Simulateswithoutcrystallosses S21-simulation results can be Filter Design Software (3):AADE Filter Design - forall filters Uilfiltdidl Univeralfilter designer andanalyzer Free, but with nag screenEt Easy touse Numerical simulation results cannot 3 Pole Butterworth -Band Pass for5 MHz with 3 MHz Bandwidth at 50 Filter Design withElsieElsie SimulationResultElsie Simulation Components to standard Values andfinite Q.

5 Simulationwithfinite export Simulation into s2p-file forComparison with HardwareFilter vs. Elsie SimulationS21S11measured-Plot1 Plot2 ElsiesimulationeofuctorS21, S11measuredPlot1, Plot2 Elsie simulationlel / Selecting Crystals: vnwa Crystal transmission(S21-measurement) standardThe vnwa Crystal Analyzer Tool:Find 3 these we want to build a Crystal Filter Enter Crystal Parameters intoAADEvom l er agenDaten vVNWA CrystalAnalyz bertraDVCA Minimum Loss (Cohn) DesignAADE Minimum Loss (Cohn) Design186 66 pF66 pF186 66 pF66 in qucs at 50 using standardComponent Values Crystals simulated with1filbt idbVNWAs1p-file obtainedbyVNWA measurement! Filter HardwareCrystal Filter Filter: Measurement vs. Simulation at 50 S21,S11measurement-Plot1,Plot2 qucs simulationS21, S11measurementPlot1, Plot2 qucs Filter: Measurement vs. Simulation at 186 S21,S11measurement-Plot1,Plot2 qucs simulationS21, S11measurementPlot1, Plot2 qucs , Measurecomponents Measurecomponents Design filtersg Simulate filters Measure filtersTry it foryourself!

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