Ionosphere

Ionospheric Measurements
- International Geophysics
- Volume 14, 1969, Pages 47-86
- https://doi.org/10.1016/S0074-6142(09)60022-X
The Radio Propagation – Discovery of the Ionosphere
- http://www.astrosurf.com/luxorion/qsl-propa2.htm
Local Reflection of Wireless Waves from the Upper Atmosphere
- Nature
- 1925
- https://doi.org/10.1038/115333a0
- This determined the height of the reflecting layer to be lower during the day than at night. The bottom of the layer during the day was rough 40-50 km and 85-100km or more at night.
A Test of the Existence of the Conducting Layer
- American Physical Society
- 1926
- https://doi.org/10.1103/PhysRev.28.554
- This determined the effective height of the reflecting layer was 50-130 miles (80-210 km).
- The height varied daily and seasonally.
Propagation of Radio Waves Round the Earth
- T. L. Eckersley
- 1927
- https://doi.org/10.1049/pws.1927.0006
- https://digital-library.theiet.org/content/journals/10.1049/pws.1927.0006
- This determined the frequency of the transmission affected reflection. The amount of reflection started dropping off for waves shorter than 10 meters (30MHz), eventually resulting in no reflection at all.