The most well-known methods of signal propagation include:

• Tropospheric ducting and tropospehric refraction tend to happen during periods of stable, anti-cyclonic weather. In these propagation methods, when the signal encounters a rise in temperature in the atmosphere instead of the normal decrease (known as a temperature inversion), the higher refractive index of the atmosphere there will cause the signal to be bent. Signals have a slow cycle of fading and will produce signals strong enough for noise-free stereo reception on FM or clear TV pictures, sometimes in full colour. Tropospheric ducting affects all frequencies, and signals enhanced this way tend to travel 500-800 miles (though some people have received "tropo", as it is usually abbreviated, from beyond 1000 miles), while with tropospheric bending, stable signals with good signal strength from 500+ miles away are not uncommon when the refractive index of the atmosphere is fairly high. Virtually all DX reception of digital television occurs by this propagation method.
• Sporadic E, or E-skip, is the result of ionospheric propagation in the E layer, in which signals bounce off highly ionized patches, or ion clouds. DX reception via the ionosphere is variable from one day to the next and is difficult to predict, thus the name sporadic E. Signals travel further through this type of propagation, due to the fact that the ionosphere is higher than the troposphere (also, signals can sometime bounce off two or more ion clouds, thereby increasing the distance of propagation: this is known as multi-hop skip.). E-skip affects the lower VHF channels, and usually enhances stations from beyond 600 miles (though there have been a handful of E-skip receptions from closer than that). On May 30, 2003, Girard Westerberg made the first known reception of digital television by sporadic E when he decoded the PSIP (Program and System Information Protocol) ID of KOTA-DT (broadcasting on channel 2 in Rapid City, South Dakota) in Lexington, Kentucky, 1,062 miles away (the current record for DTV DX reception).
• F2 propagation is related to the sunspot cycle and occurs in the F2 layer of the ionosphere, peaking every 11 years when the MUF, or Maximum Usable Frequency, is high enough to propagate TV signals. F2 tends to affect signals below 40 MHz, though it does get as high as 60 MHz. Signals have been known to travel very far through this method of propagation: On January 31, 1981, Todd Emslie received audio transmitted from London, England by the BBC's television service... in Sydney, Australia, 10,560 miles away. (At the time, the BBC were still using VHF frequencies to broadcast television.) Pictures propagated through F2 tends to be very smeared, unlike pictures through E's and tropo.
• Meteor scatter occurs when a signal reflects off a meteor. The signals come out as sporadic bursts.