Transcript The N2PK Vector Network Analyzer

The N2PK
Vector Network Analyzer
(N2PK VNA)
Paul Kiciak, N2PK
What Does “Vector” Mean?
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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
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Some “Networks”
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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:
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Examples:
 1-ports: antenna, R, L, C
 2-ports: filters, pair of antennas
 4-port: directional coupler
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What Does A VNA Measure?
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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)
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Some VNA History
HP 8410A – late 60’s, 110 MHz-12.4 GHz
Agilent E5071C – current, 9 kHz-3 GHz
HP 8753C – late 80’s, 300 kHz-6 GHz
N2PK VNA (by VE3MM) – current, 50 kHz-60 MHz
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Key Specs
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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
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.
How Does It Work?
F + aliases
O
RF
LO
.
F + aliases
O
RF
LO
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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)
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Expanded N2PK VNA
(F + aliases)
O
Optional Transverter for VHF/UHF
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Hardware
Single Detector PCB
VE3IVM Dual Detector PCB
Reflection Bridge PCB
Power Board
Calibration standards
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Some N2PK VNAs
SM0CFO+SM6PXJ
W8WWV
AG4AY
OZ1DUG
GM4SEK
VE7IT - standalone
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Software
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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)
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Some Test Results
N2PK DOS - Reflection
Exeter - Reflection
N2PK DOS - Transmission
VNA4win - Transmission
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How Good Is It?
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Correlations with commercial VNAs
Transmission
Reflection
F
-1
10
20
30
40
50
60
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Rs, ohms
------------------N2PK 8753C Delta
----- ----- ----25.20 19.25 +5.95
24.98 24.97 +0.01
24.96 24.97 -0.01
24.97 24.98 -0.01
24.98 24.95 +0.03
24.98 25.00 -0.02
24.97 25.00 -0.03
Cs, pF
------------------N2PK 8753C Delta
----- ----- ----198.6 199.3
-0.7
199.2 199.1
+0.1
199.9 200.1
-0.2
201.1 202.1
-1.0
202.9 202.9
0.0
205.0 206.2
-1.2
207.8 208.6
-0.8
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
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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 20032004 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
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Web Resources
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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/[email protected]/newfile.htm
Lawrence Glaister, VE7IT – standalone VNA: N2PK VNA PCB + custom controller & display
http://members.shaw.ca/swstuff/vna.html
Windows software:
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Exeter, Greg Ordy, W8WWV:
http://www.seed-solutions.com/gregordy/Software/Exeter.htm
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VNA4win, Roger Blackwell, GM4PMK, & Ian White, GM3SEK:
http://www.marsport.org.uk/vna4win/index.htm
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WinVNA, Joakim Soya, OZ1DUG:
http://www.planker.dk/oz6frs/2004/Projekter/Igang/N2PK/N2PK_VNA.htm
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IVMan Lite data file viewer, Ivan Makarov, VE3IVM:
http://www.makarov.ca/vna_ivmanlite.htm
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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
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