HAM RADIO LINKS

Ionosphere Notes

Properties

Total internal refraction vertical waves pass out. Shallower incident angle waves reflected. Hence underwater a clear area is over ahead but silvery mirror like farther out.

Plasma frequency varies as root n sub e. ...roughly 9 KHz*sqrt(n) or

Above plasma freq, waves not refracted/reflected

Above 40 MHz, waves just go straight through.

Higher freq longer skip distance.

For long range

During day, ionized level drops lower, leading to higher n and thus high freq of reflected wave. Higher ionosphere gives longer skip. At night, ionosphere is higher and thus longer skip

Note: 80-meters is easier to work at dawn then at dusk. D layer is still reforming., so absorption is lower.

κ= e2 ne νe/(2εomcμ)1/( ν2+ 4π2 f2 )

where nu =  electron collision freq.