Ionosphere

From wikipost

The ionosphere is defined as the layer of the Earth's atmosphere that is ionized by solar and cosmic radiation. It lies 75-1000 km (46-621 miles) above the Earth. (The Earth's radius is 6370 km, so the thickness of the ionosphere is quite tiny compared with the size of Earth.)



Layers:

Layer Height Effect Active Daytime Characteristics Night time Characteristics Usage
F2 150 - 500km refract day and night Refracts below MUF (~30MHz) Refracts below MUF (~30MHz) night-time DX
F1 150 - 500km refract daytime Refracts below MUF (~30MHz) weak refraction
Es ? refract Sporadic Refracts below 50MHz Refracts below 50MHz DX
E 90 - 150km refract daytime Refracts below 10MHz weak refraction after sunset working greyline DX
D 60 - 90km absorb nighttime Attenuates <10MHz peak attenuation at noon minimal local MF and low HF stations during the day



Bands:

Band Frequency Best at Worst at Typical use
630m 470kHz Night Day only usable during the night, local
160m 1.8MHz Night Day only usable during the night, local
80m 3.6MHz Night daytime DX at night, local during the day
40m 7.1MHz Night DX at night, local during the day
30m 10MHz
20m 14.1MHz day and night most reliable DX band
15m 21MHz day and night
10m 28MHz day night daytime to early evening
6m 50MHz day night daytime to early evening