Antenna Topics

  1. All-band doublet - W4RNL - Part 1
  2. All-band doublet - W4RNL - Part 2
  3. Balun - Air-wound
  4. Balun - Bead baluns
  5. Balun - Choosing the correct balun
  6. Bazooka dipole antenna
  7. End-fed 40-ft vertical - W5CSU
  8. End-fed 43-ft vertical - AD5X
  9. End-fed base loading - AD5X
  10. End-fed base loading - N4SPP
  11. End-fed multiband - BalunDesigns
  12. End-fed multiband - EARC Hawaii
  13. End-fed multiband - Rain gutter
  14. End-fed multiband - W3EDP
  15. End-fed 6-meter Zepp
  16. Extended double Zepp - W4RNL
  17. Field guide to HF dipoles
  18. Fold, bend, and mutilate
  19. G5RV antenna re-visited
  20. G5RV multi-band antenna
  21. L-antenna
  22. L-antenna - all-band inverted-L
  23. L-antenna - up & outer
  24. Loading short antennas
  25. Multiband parallel dipoles
  26. Non-resonant vs resonant antenna
  1. NVIS-Near Vertical Incident Skywave
  2. Only one wire - NorCal doublet
  3. Radials - ground radial systems
  4. Radials - rules of thumb for radials
  5. Radials - vertical antennas
  6. Radials - why radials
  7. RFI guide - Using ferrite beads
  8. Small magnetic loop antennas
  9. Small magnetic loop - Army loop
  10. Small magnetic loop - Coupling loops
  11. Small magnetic loop - History
  12. Small magnetic loop - K5IJB
  13. Small magnetic loop - Patterson
  14. Small magnetic loop - QRP tuner
  15. Small magnetic loop - Theory
  16. Small magnetic loop calculator
  17. Verticals - 2m vertical dipole
  18. Verticals - HF basics - W4RNL
  19. Windom - G8ODE 4-band FD3
  20. Windom - G8ODE study of OCF
  21. Windom - K1POO 4-band w/o tuner
  22. Windom - K4ABT measurements
  23. Windom - W4RNL OCF fundamentals
  24. Windom - New Carolina windom
  25. Windom - off-center vs. center-fed
  26. WI'RE we using wire

Where does 468 come from

Ionosphere Layers

Two measurements are available from magnetometer data:
____Average daily solar flux SFI index at or above 80 best for propagation
____Average daily planetary A index at or below 10 best for propagation
____Three-hour K index at or below 3 best for propagation

Three conditions are desired for good HF conditions:
_____________1.  Quiet geomagnetic field
_____________2.  High solar flux (SFI index)
_____________3.  High sunspot numbers

Higher geomagnetic numbers indicate higher ionosphere absorption.