The N2PK Vector Network Analyzer

(N2PK VNA)

Paul Kiciak, N2PKPaul Kiciak, N2PK

What Does “Vector” Mean? Vector: magnitude & direction (angle)Vector: magnitude & direction (angle) Scalar: magnitude onlyScalar: magnitude only Scalars: 22 MPH, 50 ohms, 6 dBScalars: 22 MPH, 50 ohms, 6 dB Vectors:Vectors:

Wind: 22 MPH from SSEWind: 22 MPH from SSE Impedance: 25 ohms @ -12 degreesImpedance: 25 ohms @ -12 degrees Reflection: 0.50 @ 155 degrees Reflection: 0.50 @ 155 degrees

Polar vs. Rectangular Vectors Polar vs. Rectangular Vectors Equivalent representationsEquivalent representations Polar: 25 ohms @ -12 deg.Polar: 25 ohms @ -12 deg. Rectangular: 24.45-j5.20 ohmsRectangular: 24.45-j5.20 ohms

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Some “Networks” General:General:

Black box: don’t care what’s insideBlack box: don’t care what’s inside ‘ ‘Ports’ instead of ‘inputs’ & ‘outputs’Ports’ instead of ‘inputs’ & ‘outputs’ Number of Parameters: N*N for N-port Number of Parameters: N*N for N-port DUT: N-Port Device Under TestDUT: N-Port Device Under Test 2-port: 2-port:

Examples:Examples: 1-ports: antenna, R, L, C1-ports: antenna, R, L, C 2-ports: filters, pair of antennas2-ports: filters, pair of antennas 4-port: directional coupler4-port: directional coupler

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What Does A VNA Measure? Reflection Parameters:Reflection Parameters:

Impedance*, Admittance*, SWR, Return Loss, Reflection Coefficient*Impedance*, Admittance*, SWR, Return Loss, Reflection Coefficient* Equivalent series & parallel R, L, CEquivalent series & parallel R, L, C QQ

Transmission Parameters: Transmission Parameters: Gain*, dBGain*, dB Group delay in secondsGroup delay in seconds

Components:Components: Antennas, coax, …Antennas, coax, … Inductors, capacitors, resistorsInductors, capacitors, resistors Filters: crystal, LC, …Filters: crystal, LC, … Amplifiers & attenuatorsAmplifiers & attenuators Duplexers, diplexers, directional couplers, …Duplexers, diplexers, directional couplers, … Diodes, transistors, …Diodes, transistors, …

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* Complex (vector)

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HP 8410A – late 60’s, 110 MHz-12.4 GHz HP 8753C – late 80’s, 300 kHz-6 GHz

Some VNA History

Agilent E5071C – current, 9 kHz-3 GHz N2PK VNA (by VE3MM) – current, 50 kHz-60 MHz

Key Specs Frequency Range: Frequency Range:

VNA: 50 kHz – 60 MHz, 0.034 Hz stepsVNA: 50 kHz – 60 MHz, 0.034 Hz steps LO source: <1 Hz with Hi-Z loadLO source: <1 Hz with Hi-Z load

Detectors options:Detectors options: Single or dualSingle or dual Slow, single rate (original)Slow, single rate (original) Fast, variable rateFast, variable rate

Fast Detector Rates:Fast Detector Rates: 10 rates, software selectable10 rates, software selectable 3.5 freqs/sec @ slowest rate3.5 freqs/sec @ slowest rate 900 freqs/sec @ fastest rate900 freqs/sec @ fastest rate

Dynamic Range (w/o averaging):Dynamic Range (w/o averaging): >110 dB dynamic range @ slowest rate>110 dB dynamic range @ slowest rate 90 dB dynamic range @ fastest rate90 dB dynamic range @ fastest rate

Effective Detector RF Bandwidth:Effective Detector RF Bandwidth: 7 Hz @ slowest rate7 Hz @ slowest rate 3.4 kHz @ fastest rate3.4 kHz @ fastest rate Virtually immune to external signals (antenna testing) Virtually immune to external signals (antenna testing)

No adjustmentsNo adjustments PC software controlled via Parallel port or USB portPC software controlled via Parallel port or USB port

Standalone version by VE7IT – built-in controller & displayStandalone version by VE7IT – built-in controller & display Homebrew: $250 for a single detector versionHomebrew: $250 for a single detector version

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How Does It Work?

RF & LO Direct Digital Synthesis (DDS) SourcesRF & LO Direct Digital Synthesis (DDS) Sources Linear Detector: Synchronous Direct Conversion to DC Linear Detector: Synchronous Direct Conversion to DC Sequential Quadrature: 0 deg, then 90 deg, & the difference is VERY accurateSequential Quadrature: 0 deg, then 90 deg, & the difference is VERY accurate 24 bit Analog to Digital Converter (ADC)24 bit Analog to Digital Converter (ADC)

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.

R FL OF + a l i a s e sO

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R FL OF + a l i a s e sO

.

RF

LO

F + aliasesO

Expanded N2PK VNA

01/22/07 N2PKOptional Transverter for VHF/UHF

(F + a liases)O

Hardware

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Single Detector PCB VE3IVM Dual Detector PCB

Reflection Bridge PCB

Calibration standards

Power Board

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SM0CFO+SM6PXJ AG4AY

Some N2PK VNAs

W8WWV OZ1DUG VE7IT - standalone

GM4SEK

Software N2PK DOS based (programs function in DOS or Windows) N2PK DOS based (programs function in DOS or Windows)

ReflectionReflection Open/Short/Load (OSL) calibrationOpen/Short/Load (OSL) calibration Optional Low-Loss Capacitor (LLC) standard for low-loss & Hi-Q DUTsOptional Low-Loss Capacitor (LLC) standard for low-loss & Hi-Q DUTs

TransmissionTransmission Through calibration (assumes 50 ohm source and load impedances)Through calibration (assumes 50 ohm source and load impedances)

Reflection & TransmissionReflection & Transmission OSL and Through – real time simultaneous reflection and transmissionOSL and Through – real time simultaneous reflection and transmission Optional 12-term error correction with S-Parameter Test SetOptional 12-term error correction with S-Parameter Test Set

Special Test Programs:Special Test Programs: VNA RF Self-Test (Vs, Zs, Zd)VNA RF Self-Test (Vs, Zs, Zd) Crystals (Fs, Fp, Rm, Lm, Cm, Co, Q)Crystals (Fs, Fp, Rm, Lm, Cm, Co, Q) Coax (Zo, attenuation constants)Coax (Zo, attenuation constants) Component modeling (future)Component modeling (future)

Windows programs (all do reflection or transmission & good graphics)Windows programs (all do reflection or transmission & good graphics) Exeter (W8WWV)Exeter (W8WWV) VNA4win (GM4PMK & GM3SEK)VNA4win (GM4PMK & GM3SEK) WINVNA (OZ1DUG)WINVNA (OZ1DUG)

Windows Data File ViewersWindows Data File Viewers IVMan Lite (VE3IVM)IVMan Lite (VE3IVM) Zplots (AC6LA’s Excel app)Zplots (AC6LA’s Excel app)

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N2PK DOS - Reflection N2PK DOS - Transmission

Some Test Results

Exeter - Reflection VNA4win - Transmission

How Good Is It? Correlations with commercial VNAs

Rs, ohms Cs, pFRs, ohms Cs, pF

------------------- -------------------------------------- -------------------

F N2PK 8753C Delta N2PK 8753C DeltaF N2PK 8753C Delta N2PK 8753C Delta

-- ----- ----- ----- ----- ----- ------- ----- ----- ----- ----- ----- -----

1 25.20 19.25 +5.95 198.6 199.3 -0.71 25.20 19.25 +5.95 198.6 199.3 -0.7

10 24.98 24.97 +0.01 199.2 199.1 +0.110 24.98 24.97 +0.01 199.2 199.1 +0.1

20 24.96 24.97 -0.01 199.9 200.1 -0.220 24.96 24.97 -0.01 199.9 200.1 -0.2

30 24.97 24.98 -0.01 201.1 202.1 -1.030 24.97 24.98 -0.01 201.1 202.1 -1.0

40 24.98 24.95 +0.03 202.9 202.9 0.040 24.98 24.95 +0.03 202.9 202.9 0.0

50 24.98 25.00 -0.02 205.0 206.2 -1.250 24.98 25.00 -0.02 205.0 206.2 -1.2

60 24.97 25.00 -0.03 207.8 208.6 -0.860 24.97 25.00 -0.03 207.8 208.6 -0.8

Reflection Transmission

Jack Smith, K8ZOA (http://www.cliftonlaboratories.com/faq.htm) "If you are interested in filter analysis, you should really look into the N2PK VNA. There's a Canadian ham

selling PCBs for it. I have one (one of the W8WWV group purchase) and it's an excellent piece of gear--within its frequency range fully as accurate as any of my HP network analyzers. "

Ian White, GM3SEK, (http://lists.contesting.com/_rfi/2004-06/msg00002.html) “The N2PK vector network analyzer has superb accuracy, even by professional standards; " Ian White, GM3SEK, (http://lists.contesting.com/archives//html/Towertalk/2006-12/msg00937.html) "Compared with amateur-market instruments that rely on build quality alone, the use of calibrations takes the

N2PK into the professional league for accuracy. " Rudy Severns, N6LF, (http://www.antennasbyn6lf.com/files/160_m_vertical_measurements.pdf) "The impedance measurements were straight forward. These measurements were made using an N2PK vector

network analyzer. Crosschecking with an HP 3577A analyzer, the measurements appear to be better than 1% which is more than adequate. "

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Publications

Pat Hawker, G3VA, "Technical Topics", Sept. 2004, RadComPat Hawker, G3VA, "Technical Topics", Sept. 2004, RadCom Ian White, G3SEK, photo of his VNA on RadCom cover, Oct 2004Ian White, G3SEK, photo of his VNA on RadCom cover, Oct 2004 Ian White, G3SEK, "In Practice" Oct 2004, RadCom, Ian White, G3SEK, "In Practice" Oct 2004, RadCom, http://http://wwwcowwwco..

ukuk/g3sek/in-/g3sek/in-pracprac/61_62_/61_62_radcomradcom_oct04._oct04.pdfpdf A photo of the VNA PCB of the RF DDS, cover of the RSGB 2003-A photo of the VNA PCB of the RF DDS, cover of the RSGB 2003-

2004 Annual Report2004 Annual Report Giancarlo Moda, I7SWX, April 2004, Radio Rivista, "IL VECTOR Giancarlo Moda, I7SWX, April 2004, Radio Rivista, "IL VECTOR

NETWORK ANALYZER DI N2PK“NETWORK ANALYZER DI N2PK“ Bob Cerreto, WA1FXT, January 2006, Bacon Bits Quarterly Bob Cerreto, WA1FXT, January 2006, Bacon Bits Quarterly

Newsletter, Newsletter, http://www.http://www.fpqrpfpqrp.com/BBITS/BBQ0106.PDF .com/BBITS/BBQ0106.PDF and The and The QRP Quarterly, Spring 2006QRP Quarterly, Spring 2006

John Devoldere, ON4UN, "Low-Band DXing", 4th Edition, Section John Devoldere, ON4UN, "Low-Band DXing", 4th Edition, Section 3.6.9, pg 11-343.6.9, pg 11-34

Dave Roberts, G8KBB, "USB Interfacing“, Oct. 2005, RadComDave Roberts, G8KBB, "USB Interfacing“, Oct. 2005, RadCom

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Web Resources Agilent - VNA Fundamentals:Agilent - VNA Fundamentals: http://cp.literature.http://cp.literature.agilentagilent.com/.com/litweblitweb//pdfpdf/5965-7707E./5965-7707E.pdfpdf Paul Kiciak, N2PK – documentation, build info, DOS software:Paul Kiciak, N2PK – documentation, build info, DOS software: http://n2pk.comhttp://n2pk.com Greg Ordy, W8WWV - build info: Greg Ordy, W8WWV - build info: http://www.seed-solutions.com/http://www.seed-solutions.com/gregordygregordy/Amateur Radio/Experimentation/N2PKVNA/N2PKVNA./Amateur Radio/Experimentation/N2PKVNA/N2PKVNA.htmhtm Ivan Makarov, VE3IVM - build info:Ivan Makarov, VE3IVM - build info: http://www.http://www.makarovmakarov.ca/.ca/vnavna..htmhtm Ian White, GM3SEK - build info:Ian White, GM3SEK - build info: http://www.ifwtech.co.uk/g3sek/in-prac/best-of.htm#n2pkhttp://www.ifwtech.co.uk/g3sek/in-prac/best-of.htm#n2pk Dave Roberts, G8KBB, VNA USB interface:Dave Roberts, G8KBB, VNA USB interface: http://uk.geocities.com/g8kbb@btinternet.com/newfile.htmhttp://uk.geocities.com/g8kbb@btinternet.com/newfile.htm Lawrence Glaister, VE7IT – standalone VNA: N2PK VNA PCB + custom controller & displayLawrence Glaister, VE7IT – standalone VNA: N2PK VNA PCB + custom controller & display http://members.http://members.shawshaw.ca/.ca/swstuffswstuff//vnavna.html.html Windows software:Windows software:

Exeter, Greg Ordy, W8WWV:Exeter, Greg Ordy, W8WWV: http://www.seed-solutions.com/http://www.seed-solutions.com/gregordygregordy/Software/Exeter./Software/Exeter.htmhtm VNA4win, Roger Blackwell, GM4PMK, & Ian White, GM3SEK:VNA4win, Roger Blackwell, GM4PMK, & Ian White, GM3SEK: http://www.http://www.marsportmarsport.org..org.ukuk/vna4win/index./vna4win/index.htmhtm WinVNA, Joakim Soya, OZ1DUG:WinVNA, Joakim Soya, OZ1DUG: http://www.http://www.plankerplanker..dkdk/oz6frs/2004//oz6frs/2004/ProjekterProjekter//IgangIgang/N2PK/N2PK_VNA./N2PK/N2PK_VNA.htmhtm IVMan Lite data file viewer, Ivan Makarov, VE3IVM:IVMan Lite data file viewer, Ivan Makarov, VE3IVM: http://www.http://www.makarovmakarov.ca/.ca/vnavna__ivmanliteivmanlite..htmhtm Zplots Excel data file viewer, Dan Macguire, AC6LA:Zplots Excel data file viewer, Dan Macguire, AC6LA: http://www.ac6la.com/http://www.ac6la.com/zplotszplots.html.html

N2PK-VNA Yahoogroup (almost 500 members):N2PK-VNA Yahoogroup (almost 500 members): http://groups.yahoo.com/group/N2PK-VNAhttp://groups.yahoo.com/group/N2PK-VNA 01/23/07

N2PK