1. HF Antennas and Propagation Beyond line-of-sight Glenn Dixon AC7ZN

4. My first shortwave radio

5. My First Antenna: first signal

6. L-3 Antennas Just point them L-3 Propagation Line of Sight

7. BORING But Reliable

8. HF (VHF) Propagation Modes Ocean Wave Ground Wave Ionospheric Waveguide Ionosphere (Many modes) Earth Moon Earth (EME) Tropospheric Ducting Meteor Scatter Sporadic E Rain Scatter Airplane reflection Auroral Backscatter Lightning Scatter Line-of-sight Diffraction Repeaters and Satellites Handbook and Antenna Book are excellent

9. Ionospheric Propagation Main HF long distance propagation mode Worldwide distances achievable with low power 1.6-10MHz (160-30 meters) active at night 10MHz (30 Meters and higher) and above active during day Higher bands depend on solar flux strength (unfortunately very weak currently) Always surprises Gray line Dead band?

11. NOISE and INTERFERENCE Atmospheric Noise Manmade Noise Power supplies Motor controllers Light controllers OTH Radar Military Etc. etc. etc. It’s getting worse! (Switching supply travails) China Supplies Rixos Turkey

12. It’s Not the Radio, It’s the Antenna! Two modern radios set to same frequency and modes, connected to same speaker and antenna will sound EXACTLY the same except in unusual circumstances. “Hot” Receiver? Two different antennas, however, will often have very different performance. Japan reception Hooper

13. Antenna Modelling

15. HF Antenna Modelling typically uses NEC (NEC2, NEC4). (Old FORTRAN program) Includes ground effects, skin effect, can include transmission lines, multiple sources, poor conductors, etc. Difficult to include terrain and house wiring, aluminum roofs and siding, etc. 4NEC2…free software EZNEC+ what I use…ARRL class available (?) Antenna Book has free version Many antennas one of several basic types Modelling used to determine subtle differences like SWR bandwidth, etc. Happy to model something for you.

16. Inputs: Element thickness, orientation, conductivity, xyz position Source type and value Transmission lines Ground characteristics Segmentation Frequency band Outputs: Azimuth and elevation plots (calibrated in dBi) 2D, 3D SWR vs. Frequency

18. Some HF Antenna Rules of thumb The bigger the better (sorta) The higher the better (sorta) Directional much better than ISO. Better signal/noise Less Fading Can be difficult in nets, etc.

19. World’s Cheapest Antenna (that can transmit) This 20 M version $3.15 in new materials. Use what you have End fed half wave popular with QRP’rs My EFCF antenna

20. ½ wave dipole Bottom ¼ wave is transmission line and counterpoise Use what you have (zip cord, magnet wire, etc.) Wire impedance not important. Position point A about three feet off ground. Bottom segment length determined by velocity factor. Others by speed of light. Not critical. Will give good SWR over reasonable band Fairly low radiation angle regardless of orientation. Not sure why this is not more popular… A

21. EFCF Antenna

22. What I’m having fun with: Inflatable Antennas (dismal failures) Kite Spar antennas Multirotor applications Suspend the EFCF antenna Bigger? Measure antennas

23. HF Antenna Future Covenants: Legislation? (relevant?) Stealth More aesthetically pleasing Temporarily deployable Remote Sites

24. Links: Radio Handbook and Antenna Book: ARRL.org Propagation: dx.qsl.net/propagation Eznec: eznec.com 4nec2: qsl.net/4nec2