S.N.A.T.

Report
Network Analyzer Terminal Scalar Network Analyzer
Dave Collins –
AD7JT
George Heron –
N2APB
Poor Ham’s Scalar Network Analyzer (PHSNA)
With Network Analyzer Terminal (NAT)
TERMINAL (NAT)
POWER READINGS (dB)
LOGARITHMIC
RF POWER
METER
(AD8307)
< SERIAL INTERFACE >
SCAN PARAMETERS
POWER
LEVEL
ARDUINO-BASED
MICROCONTROLLER
RF OUT
DEVICE UNDER
TEST (DUT)
FREQ
RF IN
DIGITALLY
CONTROLLED
SIGNAL
GENERATOR
(AD9850/51)
https://groups.yahoo.com/neo/groups/PHSNA/info
Features
• Handheld graphic terminal for display and control of the PHSNA
• 3.2”, 240 x 320, 16-bit color graphic LCD display & touch panel
• User-friendly operator interface
• Field upgradable firmware
• Serial port connection to PHSNA (digital UART 3.3V)
• Keyboard input for control of SSNA menu system
• 32KB EEPROM for persistent storage (settings and options)
• 14 Macros (in EEPROM) for storing operating parameters
• PLX-DAQ (Excel) mode for test automation and PHSNA compat.
• Compatible with standard and enhanced PHSNA f/w versions
• Simplified calibration (no curve fitting required)
• Measurement & Plot Capabilities (v1.0):
- Testing and evaluating filters
- Measuring crystal parameters
- Return Loss Measurement
- VSWR and antenna tuning
- Continuous/repeated operation options
• SD Card mass storage up to 1 GB provides:
- FAT16 file system compatibility
- Subdirectory support for easy file management
- Data spooling and playback
- Calibration data storage and reloading
- Direct data exchange with Windows and Linux apps
- Easy and efficient firmware upgrades
- DOS–like commands to manage and playback data files
Specifications
PCB: 4.47" x 3.31"
Enclosure: 4.82" x 3.77" x 1.39"
Data rates: 1.2 to 19.2 kbaud
Power: 12V DC @ 120ma (typ) (330ma for NACT with DDS-60)
Weight: 7 oz (approx)
Display module - under $20 on eBay:

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240 x 320 Pixel (QVGA), 16-bit color, 3.2” LCD
SSD1289 display controller
Resistive touch screen with ADS7843 controller
SD Card socket
Pads and interconnect for serial (SPI) EEPROM
Single, 40-pin interface connector
Basic NAT Block Diagram
(Versions 1 and 2)
Menu Mode screen shots
1
ENTER
PLX Mode screen shots
Enter
F1
SPACE
DOS Mode screen shots
Scroll
Lock
touch
Escape
Y
touch
Optional PC Application
< SERIAL INTERFACE >
RF IN
Scalar Network
Analyzer
(SNA)
DEVICE UNDER
TEST (DUT)
RF OUT
NAT-SNA: NAT-Scalar Network Analyzer
Block Diagram (Version 4)
NACT to SNA conversion
RF Power Meter by Dick Faust, K9IVB
http://www.k9ivb.net/RF_Power_Meter/

RF Power Meter Mode



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Primarily intended for QRP applications
Power reading taken about 200 times/second (every 5 ms)
100 dBm range, use attenuators to shift the range
DDS used only for calibration
Three Power Meters Displayed
 Current power reading (10-point running average)
 Average Power (200-point running average)
 Peak Power (updated every 200 samples)
Scroll
Lock
P
Ctrl-G
Apply
RF
Antenna analysis with Return Loss Bridge (RLB)
RF INPUT
(FROM DDS)
50 
50 
10T-Bifilar
(FT37-43)
RESONATING DUT
(e.g., antenna)
50 
RETURN LOSS
(TO RF POWER METER)
RETURN LOSS BRIDGE
Antenna analysis with Return Loss Bridge (RLB)
Crystal Characterization & Matching
RF
OUT
-3dB Attenuator
9.1
9.1
150
10T-Bifilar
(FT37-43)
10T-Bifilar
(FT37-43)
CRYSTAL
SOCKET
CRYSTAL TEST FIXTURE
RF
IN
-3dB Attenuator
9.1
9.1
150
Crystal Characterization & Matching (cont.)
Crystal Characterization & Matching (cont.)
References:
http://www.midnightdesignsolutions.com/nat
https://groups.yahoo.com/neo/groups/NAT-SNA/info
https://groups.yahoo.com/neo/groups/PHSNA/info
Dave [email protected] and George [email protected]
QUESTIONS?
COMMENTS?
CRITIQUES?

Time for a little math

Gain ratio = Pout/Pin

Gain (dB) = 10 log(Pout/Pin)

Gain (dBm) = 10 log(Pout/.001) = 10 log(Pout x 1000)
= 10 (log(Pout) + log(1000)) = 10 log(Pout) + 30

Short circuit gain = 10 log(Pin/Pin) = 10 log(1) = 0
for any Pin

Gain (dBm) = 10 log(Pin) - d
where:
Pin = power meter reading
d = short circuit gain reading

DDS output level varies with
frequency (due to sin(x)/x
sampling effect) therefore
d is a function of
frequency: d(f)

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