Editing TV and FM DX (section)

==Transequatorial propagation (TEP)==
Discovered in 1947, transequatorial spread-F (TE) propagation makes it possible for reception of television and radio stations between {{convert|3000|-|5000|mi|km}} across the [[equator]] on frequencies as high as 432 MHz. Reception of lower frequencies in the 30 – 70 MHz range are most common. If sunspot activity is sufficiently high, signals up to 108 MHz are also possible. Reception of TEP signals above 220 MHz is extremely rare. Transmitting and receiving stations should be nearly equidistant from the [[geomagnetic]] [[L-shell|equator]].

The first large-scale VHF TEP communications occurred around 1957 – 58 during the peak of solar cycle 19. Around 1970, the peak of cycle 20, many TEP contacts were made between Australian and Japanese radio amateurs. With the rise of cycle 21 starting around 1977, amateur contacts were made between [[Greece]]/[[Italy]] and Southern Africa (both South Africa and [[Rhodesia]]/[[Zimbabwe]]), and between Central and South America by TEP.

"Afternoon" and "evening" are two distinctly different types of trans-equatorial propagation.

===Afternoon TEP===
Afternoon TEP peaks during the mid-afternoon and early evening hours and is generally limited to distances of {{convert|4000|-|5000|mi|km}}. Signals propagated by this mode are limited to approximately 60 MHz. Afternoon TEP signals tend to have high signal strength and suffer moderate distortion due to multipath reflections.

===Evening TEP===
The second type of TEP peaks in the evening around 1900 to 2300 hours local time. Signals are possible up to 220 MHz, and even very rarely on 432 MHz. Evening TEP is quenched by moderate to severe geomagnetic disturbances. The occurrence of evening TEP is more heavily dependent on high solar activity than is the afternoon type.

During late September 2001, from 2000 to 2400 local time, VHF television and radio signals from [[Japan]] and [[Korea]] up to 220 MHz were received via evening transequatorial propagation near [[Darwin, Northern Territory]].<ref name="darwin_DX">{{cite web |last1=Mann |first1=Tony |last2=Emslie |first2=Todd |title=Darwin, Australia VHF DXpedition |url=http://home.iprimus.com.au/toddemslie/darwin-dxpedition.html |url-status=dead |archive-url=https://web.archive.org/web/20220518052319/http://home.iprimus.com.au/toddemslie/darwin-dxpedition.html |archive-date= May 18, 2022 |access-date=May 16, 2024 |work=Todd Emslie's TV DX Page}}</ref>