Many Radio Amateurs are hunting DX i.e. stations outside your own continent.
DXing on low bands from 160 to 30 meter, we often have useful help of greyline propagation to boost the chances of making a QSO.
On higher bands we need high solarflux and MUF must have reached the band we wish to use to obtain QSO.
|ELF||Extremely Low Frequency||3–300 Hz||1000-100,000 km|
|VLF||Very Low Frequency||3–30 kHz||100–10 km||Guided between the earth and the ionosphere.|
|LF||Low Frequency||30–300kHz||10–1 km||Guided between the earth and the D layer of the ionosphere.|
|MF||Medium Frequency||300–3000kHz||1000–100 m||Surface waves.
E, F layer ionospheric refraction at night, when D layer absorption weakens.
|HF||High Frequency (Short Wave)||3–30 MHz||100–10 m||E layer ionospheric refraction.
F1, F2 layer ionospheric refraction.
|VHF||Very High Frequency||30–300MHz||10–1 m||Infrequent E ionospheric (Es) refraction. UncommonlyF2 layer ionospheric refraction during high sunspot activity up to 50 MHz and rarely to 80 MHz. Generally direct wave. Sometimes tropospheric ducting.|
|UHF||Ultra High Frequency||300–3000MHz||100–10 cm||Direct wave. Sometimes tropospheric ducting.|
|SHF||Super High Frequency||3–30 GHz||10–1 cm||Direct wave.|
|EHF||Extremely High Frequency||30–300GHz||10–1 mm||Direct wave limited by absorption.|