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The N2PK Vector Network Analyzer (N2PK VNA)

The N2PK Vector Network Analyzer (N2PK VNA). Paul Kiciak, N2PK. What Does “Vector” Mean?. Vector: magnitude & direction (angle) Scalar: magnitude only Scalars: 22 MPH, 50 ohms, 6 dB Vectors: Wind: 22 MPH from SSE Impedance: 25 ohms @ -12 degrees Reflection: 0.50 @ 155 degrees

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The N2PK Vector Network Analyzer (N2PK VNA)

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  1. The N2PK Vector Network Analyzer(N2PK VNA) Paul Kiciak, N2PK

  2. What Does “Vector” Mean? • Vector: magnitude & direction (angle) • Scalar: magnitude only • Scalars: 22 MPH, 50 ohms, 6 dB • Vectors: • Wind: 22 MPH from SSE • Impedance: 25 ohms @ -12 degrees • Reflection: 0.50 @ 155 degrees • Polar vs. Rectangular Vectors • Equivalent representations • Polar: 25 ohms @ -12 deg. • Rectangular: 24.45-j5.20 ohms 01/22/07 N2PK

  3. Some “Networks” • General: • Black box: don’t care what’s inside • ‘Ports’ instead of ‘inputs’ & ‘outputs’ • Number of Parameters: N*N for N-port • DUT: N-Port Device Under Test • 2-port: • Examples: • 1-ports: antenna, R, L, C • 2-ports: filters, pair of antennas • 4-port: directional coupler 01/22/07 N2PK

  4. What Does A VNA Measure? • Reflection Parameters: • Impedance*, Admittance*, SWR, Return Loss, Reflection Coefficient* • Equivalent series & parallel R, L, C • Q • Transmission Parameters: • Gain*, dB • Group delay in seconds • Components: • Antennas, coax, … • Inductors, capacitors, resistors • Filters: crystal, LC, … • Amplifiers & attenuators • Duplexers, diplexers, directional couplers, … • Diodes, transistors, … * Complex (vector) 01/23/07 N2PK

  5. Some VNA History HP 8410A – late 60’s, 110 MHz-12.4 GHz HP 8753C – late 80’s, 300 kHz-6 GHz Agilent E5071C – current, 9 kHz-3 GHz N2PK VNA (by VE3MM) – current, 50 kHz-60 MHz 01/22/07 N2PK

  6. Key Specs • Frequency Range: • VNA: 50 kHz – 60 MHz, 0.034 Hz steps • LO source: <1 Hz with Hi-Z load • Detectors options: • Single or dual • Slow, single rate (original) • Fast, variable rate • Fast Detector Rates: • 10 rates, software selectable • 3.5 freqs/sec @ slowest rate • 900 freqs/sec @ fastest rate • Dynamic Range (w/o averaging): • >110 dB dynamic range @ slowest rate • 90 dB dynamic range @ fastest rate • Effective Detector RF Bandwidth: • 7 Hz @ slowest rate • 3.4 kHz @ fastest rate • Virtually immune to external signals (antenna testing) • No adjustments • PC software controlled via Parallel port or USB port • Standalone version by VE7IT – built-in controller & display • Homebrew: $250 for a single detector version 01/22/07 N2PK

  7. How Does It Work? • RF & LO Direct Digital Synthesis (DDS) Sources • Linear Detector: Synchronous Direct Conversion to DC • Sequential Quadrature: 0 deg, then 90 deg, & the difference is VERY accurate • 24 bit Analog to Digital Converter (ADC) 01/22/07 N2PK

  8. Expanded N2PK VNA Optional Transverter for VHF/UHF 01/22/07 N2PK

  9. Single Detector PCB VE3IVM Dual Detector PCB Hardware Reflection Bridge PCB Power Board Calibration standards 01/22/07 N2PK

  10. Some N2PK VNAs SM0CFO+SM6PXJ AG4AY GM4SEK W8WWV OZ1DUG VE7IT - standalone 01/22/07 N2PK

  11. Software • N2PK DOS based (programs function in DOS or Windows) • Reflection • Open/Short/Load (OSL) calibration • Optional Low-Loss Capacitor (LLC) standard for low-loss & Hi-Q DUTs • Transmission • Through calibration (assumes 50 ohm source and load impedances) • Reflection & Transmission • OSL and Through – real time simultaneous reflection and transmission • Optional 12-term error correction with S-Parameter Test Set • Special Test Programs: • VNA RF Self-Test (Vs, Zs, Zd) • Crystals (Fs, Fp, Rm, Lm, Cm, Co, Q) • Coax (Zo, attenuation constants) • Component modeling (future) • Windows programs (all do reflection or transmission & good graphics) • Exeter (W8WWV) • VNA4win (GM4PMK & GM3SEK) • WINVNA (OZ1DUG) • Windows Data File Viewers • IVMan Lite (VE3IVM) • Zplots (AC6LA’s Excel app) 01/22/07 N2PK

  12. Some Test Results N2PK DOS - Reflection N2PK DOS - Transmission Exeter - Reflection VNA4win - Transmission 01/22/07 N2PK

  13. How Good Is It? Transmission Reflection Rs, ohms Cs, pF ------------------- ------------------- F N2PK 8753C Delta N2PK 8753C Delta -- ----- ----- ----- ----- ----- ----- 1 25.20 19.25 +5.95 198.6 199.3 -0.7 10 24.98 24.97 +0.01 199.2 199.1 +0.1 20 24.96 24.97 -0.01 199.9 200.1 -0.2 30 24.97 24.98 -0.01 201.1 202.1 -1.0 40 24.98 24.95 +0.03 202.9 202.9 0.0 50 24.98 25.00 -0.02 205.0 206.2 -1.2 60 24.97 25.00 -0.03 207.8 208.6 -0.8 • Correlations with commercial VNAs • 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. " 01/30/07 N2PK

  14. Publications • Pat Hawker, G3VA, "Technical Topics", Sept. 2004, RadCom • Ian White, G3SEK, photo of his VNA on RadCom cover, Oct 2004 • Ian White, G3SEK, "In Practice" Oct 2004, RadCom, http://wwwco.uk/g3sek/in-prac/61_62_radcom_oct04.pdf • A photo of the VNA PCB of the RF DDS, cover of the RSGB 2003-2004 Annual Report • Giancarlo Moda, I7SWX, April 2004, Radio Rivista, "IL VECTOR NETWORK ANALYZER DI N2PK“ • Bob Cerreto, WA1FXT, January 2006, Bacon Bits Quarterly Newsletter, http://www.fpqrp.com/BBITS/BBQ0106.PDF and The QRP Quarterly, Spring 2006 • John Devoldere, ON4UN, "Low-Band DXing", 4th Edition, Section 3.6.9, pg 11-34 • Dave Roberts, G8KBB, "USB Interfacing“, Oct. 2005, RadCom 01/22/07 N2PK

  15. Web Resources • Agilent - VNA Fundamentals: http://cp.literature.agilent.com/litweb/pdf/5965-7707E.pdf • Paul Kiciak, N2PK – documentation, build info, DOS software: http://n2pk.com • Greg Ordy, W8WWV - build info: http://www.seed-solutions.com/gregordy/Amateur Radio/Experimentation/N2PKVNA/N2PKVNA.htm • Ivan Makarov, VE3IVM - build info: http://www.makarov.ca/vna.htm • Ian White, GM3SEK - build info: http://www.ifwtech.co.uk/g3sek/in-prac/best-of.htm#n2pk • Dave Roberts, G8KBB, VNA USB interface: http://uk.geocities.com/g8kbb@btinternet.com/newfile.htm • Lawrence Glaister, VE7IT – standalone VNA: N2PK VNA PCB + custom controller & display http://members.shaw.ca/swstuff/vna.html • Windows software: • Exeter, Greg Ordy, W8WWV: http://www.seed-solutions.com/gregordy/Software/Exeter.htm • VNA4win, Roger Blackwell, GM4PMK, & Ian White, GM3SEK: http://www.marsport.org.uk/vna4win/index.htm • WinVNA, Joakim Soya, OZ1DUG: http://www.planker.dk/oz6frs/2004/Projekter/Igang/N2PK/N2PK_VNA.htm • IVMan Lite data file viewer, Ivan Makarov, VE3IVM: http://www.makarov.ca/vna_ivmanlite.htm • Zplots Excel data file viewer, Dan Macguire, AC6LA: http://www.ac6la.com/zplots.html • N2PK-VNA Yahoogroup (almost 500 members): http://groups.yahoo.com/group/N2PK-VNA 01/23/07 N2PK

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