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HAM RADIO 2012
Evolution of the DG8SAQ
Vector Network Analyzer:
New VNWA3 Features & Applications
PROF. DR. THOMAS BAIER E-mail: [email protected]
DG8SAQ Hochschule Ulm
Prittwitzstrasse 10
89075 Ulm
English version by
Jan Verduyn G0BBL and Kurt Poulsen OZ7OU
HAM RADIO 2012 1
mailto:[email protected]:[email protected]:[email protected]
VNWA Presentation - Contents
HAM RADIO 2012 2
• What are S-parameters?
• How does the VNWA function
and how was it born?
• New features
• Some novel measurement examples
Dank an:
- Eric Hecker - Fred Schneider
- Giuseppe Gristina - Mario Armando Natali
It is all about scattering of Waves
HAM RADIO 2012 3
Incident
Reflected
Transmitted
Lens
DUT
DUT : DEVICE UNDER TEST
Optic
Electrical
a1
b1
b2
S-Parameter = Scattering Parameter Sik
HAM RADIO 2012 4
• Complex S-parameters: Sik = bi / ak
• Sik are complex numbers consisting of
Magnitude and Phase!
b1
a1
b2
a2
ZL
Tor 1 Tor 2
S21 S12
S11 S22
Zweitor
ZL
Two Port
Port 1 Port 2
S-Parameter S11
| S11 | = Input Return Loss
HAM RADIO 2012 5
DUT
a1 b2
b1
111
1
bS
a 11
11
1
1
SVSWR
S
S-Parameter S21
| S21 | = Transmission Loss
HAM RADIO 2012 6
DUT
a1 b2
b1
221
1
bS
a
The VNWA can measure these S-Parameters!
HAM RADIO 2012
DUT
DUT : DEVICE UNDER TEST
PTEE 2011 7
11S 21S
Evolution and Principle of Operation (1)
VNWA Basics
• Tunable
Signal Source
• 3 Coherent
Receivers
• Device Control
• Data Processing
and Graphics
RECEIVER / DETECTOR
PROCESSOR / DISPLAY
REFLECTED
(A)
TRANSMITTED
(B)
INCIDENT
(R)
SIGNAL
SEPARATION
Source
Incident
Reflected
Transmitted
DUT
HAM RADIO 2012 8
Evolution and Principle of Operation (2)
Functional Diagram
• Tuneable
Signal Source
• 3 Coherent
Receivers
• Device Control
• Dataprocessing
and Graphics
HAM RADIO 2012 9
Direct Digital Synthesizer (DDS)
3 Gilbert-Cell Mixers + DDS
+ PC Sound Card (IF)
Evolution and Principle of Operation (3)
Functional Block Diagram
HAM RADIO 2012 10
Evolution and Principle of Operation (4)
Problem: DDS Alias Frequencies
HAM RADIO 2012 11
RF DDS
LO DDS
All Alias-Frequencies mix down
to the same Intermediate Frequency
→ either use Low Pass filter, or…
Nyq
uis
tgre
nze
Evolution and Principle of Operation (5)
… use LO DDS with Clock Frequency Offset
HAM RADIO 2012 12
all Alias-Frequencies can now be used to
extend the VNWA Frequency Range
RF DDS
LO DDS
FC2
Evolution and Principle of Operation (6)
Result: VNWA1
HAM RADIO 2012 13
Evolution and Principle of Operation (7)
VNWA1 First Practical Use
HAM RADIO 2012 14
Evolution and Principle of Operation (8)
Updated Development Targets
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Main Target: A Tool for Education
• Frequency Range > 500 MHz
• Continous Frequency Range – no Gaps
• Constructed on PCB / reproducible Design
• Lowest possible Cost
Evolution and Principle of Operation (9)
Continous Frequency Range
HAM RADIO 2012 16
Gaps in the frequency range
at multiples of the clock frequency
Solution: variable clock frequencies by changing
PLL-clock multipliers (integrated in DDS)
Evolution and Principle of Operation (10)
Result: VNWA2
HAM RADIO 2012 17
• Frequency Range:
1 kHz…>1,3 GHz
• Dynamic Range:
>90 dB (f ≤ 500 MHz)
>60dB (f > 500 MHz)
S11, S21 Measurements
• Control via Parallel Port
• Signal processing via
external (PC) Sound Card
Layout: Dan Andersson M0DFI
Evolution and Principle of Operation (10)
Milestone 2009: VNWA from SDR-Kits
HAM RADIO 2012 18
SDRKits
=
Jan Verduyn G0BBL
• Ex Merchant Navy Radio Officer
• Ex Motorola Engineer
• Retired and started SDR-Kits
• Radio Amateur
Halle A1 Stand E812
Evolution and Principle of Operation (11)
Market impact on VNWA2 Developements
HAM RADIO 2012 19
Fewer Computers with
Parallel Port Interface
Fewer Computers with
Stereo-Line-In
Evolution and Principle of Operation (12)
VNWA2-USB
HAM RADIO 2012 20
• USB Interface
• Controller
• USB Audio Codec
• Powered from USB Only a USB cable
connection to the PC
Evolution and Principle of Operation (13)
VNWA3: Ready Assembled in Factory
HAM RADIO 2012 21
• TCXO
• Additional
Clock-PLL!!
Evolution and Principle of Operation (14)
Less Interference with flexible Clock-PLL
HAM RADIO 2012 22
VNWA2
VNWA3
Open, 8000 Points, 0,34ms/Point
VNWA3 further
optimized via Software
Evolution and Principle of Operation (15)
VNWA3 Options
HAM RADIO 2012 23
• New expansion PCB with
2nd Audio-Codec to
measure S11 and S21 simultaneously
• External Clock Input
• Possible to extend VNWA3
to a fully automatic 2 port
Analyzer with an external
Transfer Relay
VNWA3E
Applications:
Impedance Measurements (1)
HAM RADIO 2012 24
Impedance Measurements (2)
Variant 1: Return Loss Measurement
HAM RADIO 2012 25
11
11
150
1x
SZ
S
Highest
accuracy for
Zx close to 50 Ω
Cal: SOL
Impedance Measurements (3)
Variant 2: I-Messung
HAM RADIO 2012 26
RX measures current through Zx
Highest for
large values of Zx
Cal: Thru
Impedance Measurements (4)
Variant 3: V-Measurement
HAM RADIO 2012 27
RX measures
Voltage across Zx
Highest for
low values of Zx
Cal: SOL
Impedance Measurements (5)
Variante 4: RF-IV Measurement
HAM RADIO 2012 28
Zx
Combination of
V & I-Measurement
x
VZ
I
Excellent for
ALL values of Zx
RF-IV Test Head: http://www.makarov.ca/
Cal: SOL
Impedance Measurements (6)
Measurement Deviation-Variants 1 - 4
HAM RADIO 2012 29
Impact of 10% increase of Zx value
on measurement result:
RF-IV shows best overall sensitivity!
Zx S11 I V V / I
0,1 Ω -0,04% 0,01% -9,96% 9,97% 51 Ω 480,68% 3,27% -3,08% 6,56%
100 kΩ 0,01% 9,08% 0,00% 9,99%
Impedance of a 100 pF SMD Capacitor:
Effect of 2 nH in Load Standard
HAM RADIO 2012 30
Rs
Cs
Abt. 50% Rs-Error
Practically no Cs-Error
Load-Model critical for Q measurements!
HAM RADIO 2012 31
New: Low Loss Capacitor (LLC)
as an additional Calibration Standard…
Error! Still Correct!
… Fixes Load Model-
Error!!!
If you have a clock you always know what
time it is …
HAM RADIO 2012 32
With TWO Clock you are never quite
shure which time is right !
HAM RADIO 2012 33
• My two
Rubidium
Frequency
standards:
• How accurately
do they run in
sync?
1 2
Application: Frequency Comparison (1)
VNWA3 as Phase Comparator
HAM RADIO 2012 34
• Precise Phase
Measurement
with VNWA3
• Frequency
deviation
calculated from
Phase
VNWA3E
Frequency Comparison (2)
Measurement Accuracy
HAM RADIO 2012 35
• TCXO
compared
to itself
• 1s
Measurement
• abt ±10 µHz
variation!!!
3 Sweeps with 10 Points and 0,1s / Point
Frequency Comparison (3)
Rubidium 1 vs. Rubidium 2 over 260s
HAM RADIO 2012 36
Deviation = -0,0025 Hz ± 0,0003 Hz at 10 MHz
≡ 2,5∙10-10
Frequency Comparison (4)
Allan Deviation from VNWA-Measurement
HAM RADIO 2012 37 10
-1 510
0 510
1 510
2 510
3 510
4
Time [sec]
10-11
2
5
10-10
2
5
10-9
2
5
10-8
2
5
10-7
All
and
evia
tio
n/F
req
uen
cy[r
ad]
Rubidium Standard 1
measured against
Rubidium Standard 2
aus http://tf.nist.gov/general/glossary.htm
1 2
Frequency Comparison (5)
Rubidium Standard vs. VNWA3 TCXO
HAM RADIO 2012 38
Deviation = -3 Hz ± 1 Hz at 10 MHz ≡ -0,3 ppm
Application:
Time Domain Analysis (1)
HAM RADIO 2012 39
Cable
75
Ω
open Cable 25 Ω
Ca
ble
50
Ω
Frequency Domain
Time Step Response
Time Domain Analysis (2)
Locate the faulty Christmas Tree Light Bulb !!
HAM RADIO 2012 40
http://www.pa4tim.nl/?p=345
Application Example: Cavity Resonance (1)
HAM RADIO 2012 41
Lowest Resonance mode:
Cavity Resonance (2)
HAM RADIO 2012 42
8
001
3 10 m/s2,405
2 6,28 9,5cm
1209MHz
cf J
r
Cavity Resonance (3)
HAM RADIO 2012 43
Lowest Resonance mode:
Cavity Resonance (4)
HAM RADIO 2012 44
Empty
vs.
Filled
Cavity Resonance (5)
HAM RADIO 2012 45
Cavity Resonance (6)
HAM RADIO 2012 46
Rocket Tank – real VNWA3 measurements !!
Summary
HAM RADIO 2012 47
• The VNWA3 is a versatile Test
Instrument
• Suitable for many - even -
professional Applications!
• VNWAs are used on 5 Continents
The VNWA3 is in use all over the World.
HAM RADIO 2012 48
The VNWA3 is in use all over the World.
HAM RADIO 2012 49
The VNWA3 is in use all over the World..
HAM RADIO 2012 50
The VNWA3 is in use all over the World.
HAM RADIO 2012 51
The VNWA3 is in use all over the World.
HAM RADIO 2012 52
Finally, … a Warning:
VNWA´s are Addictive!
HAM RADIO 2012 53