Hello Fellow Radio Friends,
Due to the dismal Topband propagation conditions seen during the CQ WW
contest last weekend, I've received numerous requests for and explanation of
160 meter propagation correlation with propagation indices.
Unfortunately MF propagation is so complicated that the usual indices are
not clear cut indicators of 160 meter propagation conditions, like with HF
frequencies. However the following indices parameter levels will
(((generally))) point to good 160 meter propagation conditions.
1.) Dropping indices numbers are better.
2.) Solar flux under 150, under 100 better, 70 is best for E layer multi
hop.
3.) Solar flux of at least 100 for E valley-F layer ducting mechanism.
4.) Previous 24 hour Ap index under 10, under 7 for several days
consecutively is best.
5.) Previous 3 hour Kp index under 3 for mid latitude paths, under 2 for
high latitude paths, 0-1 for several days consecutively is best.
6.) Energetic protons no greater then 10 MeV (10+0).
7.) Background x-ray flux levels less than C1 for several days
consecutively.
No current STRATWARM alert.
IMF Bz with a negative sign, indicates a better chance of high latitude path
auroral absorption/unpredictable refraction or scattering of MF RF signals,
when the Kp is above 3.
See my MF radio propagation theory notes for more information
http://www.kn4lf.com/kn4lf5.htm .
73,
Thomas Giella,
KN4LF
|