Set Up WSJT-X for WSPR Mode
Before you can analyze your antenna, you need to configure the software to transmit and receive these specific low-power signals.
Mode Selection: In WSJT-X, go to the top menu and select Mode > WSPR.
Frequency: Ensure your radio is set to the correct WSPR frequency for the band you want to test (e.g., 14.0956 MHz for 20m). WSJT-X will usually handle this if your CAT control is active.
Power Settings: WSPR is designed for low power. Set your rig to 5 Watts or less. The goal is to see how your antenna performs, not to "brute force" the signal with high wattage.
Time Sync: WSPR relies on perfect timing. Ensure your PC clock is synced to within one second using a tool like NetTime or Dimension 4.
The Testing Phase (TX/RX Cycle)
Once the software is running, it will operate on a two-minute cycle.
Uploading Data: In the WSJT-X settings (File > Settings > Reporting), ensure "Enable PSK Reporter Spotting" and "Upload WSPR spots to WSPRnet" are checked.
The Beacon: Set the Upload % (usually 20–30%). This tells the software how often to transmit versus listen.
Observation: While listening, WSJT-X will decode signals from other stations. If you can hear a station in Europe but no one hears you back, it tells you something about your antenna's gain or local noise floor.
Analyze Results on WSPRnet.org
This is where the actual "checking" of your antenna happens. After letting the software run for an hour or two, visit WSPRnet.org.
Database Search: Use the "Database" tab and filter by your Callsign.
The Map: Click on the "Map" tab and enter your callsign. You will see lines connecting your station to everyone who heard you.
Evaluating Performance:
Directionality: If you have a wire antenna (like a dipole), you should see more "spots" perpendicular to the wire. If you see spots in a direction where the antenna should have a null, you may have nearby obstructions or a skewed radiation pattern.
Signal-to-Noise Ratio (SNR): Look at the SNR values reported by other stations. If stations 2,000 miles away are reporting you at -20dB while they report others at -10dB, your antenna might be mounted too low or have high SWR losses.
Practical Comparisons
To get the most out of this for antenna tuning:
A/B Testing: If you have two antennas, run WSPR on Antenna A for an hour, then switch to Antenna B for an hour under similar band conditions. Compare the "Count" and "Distance" (KM) on WSPRnet.
Time of Day: Run the test at noon and again at midnight. This helps you understand if your antenna is better suited for NVIS (Near Vertical Incidence Skywave) or long-haul DX.
Greyline Propagation: Watch the map during sunrise or sunset. This is the best time to see if your antenna can catch the "long path" to the other side of the world.
Quick Tips for Accuracy
Don't over-modulate: Ensure your ALC (Automatic Level Control) is not spiking. Keep the "Pwr" slider in WSJT-X low enough that your radio isn't struggling.
Check the Solar Flux: Use a site like QRZ.com to check the current SFI (Solar Flux Index). If the sun is quiet, poor propagation might be the atmosphere's fault, not your antenna's.
WSPR is significantly "more accurate" at finding propagation paths that other modes simply cannot see.
WSPR: Can decode signals as low as -28dB to -31dB SNR. It uses a very narrow bandwidth and a long transmission cycle (2 minutes) specifically to pull signals out of the noise.
FT8 (the main feeder for PSK Reporter): Typically decodes down to about -21dB to -24dB SNR.
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One thing to keep in mind for accuracy: PSK Reporter can sometimes be misleading because it includes many stations running "high power" (>100W). If you see your signal on the other side of the world on PSK Reporter, you don't know if it's because your antenna is great, or because you're "brute forcing" it or if the person "hearing" your signal is using a 150' beam that is pointed directly at you.
Because WSPR culture is strictly QRP (Low Power), the reports you get back are a much more "honest" reflection of your antenna's efficiency.