Amateur Radio Station · JO31HF
Signals
beyond
the horizon.
Classic RF, digital links, orbiting repeaters — and the physics behind every contact.
- CALL
- DL1CKE
- GRID
- JO31HF
- FOCUS
- HF · VHF · UHF · SAT
01 · OPERATING MODES
Choose a signal. See how it behaves.
Four modes, four very different ways to cross the same distance.
Efficient voice communication with one sideband and no transmitted carrier.
LEO · AMATEUR PAYLOAD02 · AMATEUR SATELLITES
Work the pass.
Track the orbit. Correct Doppler. Make the call before the horizon closes.
- TIME
- 02:48
- AZIMUTH
- 262°
- ELEVATION
- 52°
- DOPPLER
- +1.4 kHz
03 · ANTENNA LAB
The system starts in the air.
Compare three practical antenna concepts.
FIELD INSTALLATION · HFANT · 01
End-Fed Random Wire
Simple wire. Multiple bands. A tuner and good RF grounding complete the system.
- FEED
- At one end
- PATTERN
- Band-dependent
- USE
- HF multiband
04 · FIELD THEORY
Everything RF starts here.
Four equations. One electromagnetic universe. Select one for the plain-English version.
GAUSS · ELECTRIC FIELD
Charge creates electric flux.
The electric field flowing through a closed surface is set by the charge inside it.
05 · SPACE WEATHER
Read the sky before calling CQ.
Live Solar-Terrestrial Data from HamQSL.
This panel stays live when the page is online. Everything else works offline.
THE DEEP DIVE
Math for Radio Amateurs
From 1 + 1 to Maxwell. Serious theory — without taking it too seriously.
Download the PDF