Trans-Equatorial Propagation

Related wiki pagesBands, Propagation, Aurora, Tropospheric ducting, Lightning scatter, Meteor scatter

Simplified ionospheric models portray the ionosphere as a series of horizntal layers that vary with time, location and sunspot activity. The real ionosphere is much more complex than this, particularly in in equatorial and polar regions.

What is Trans-Equatorial Propagation (TEP)?

Historically, the effect was first noticed in the 1940's by both military and amateur operators who discovered that it is possible to communicate in the VHF band over intercontinental distances during times of high sunspot activity.

The first organised and therefore relatively large scale TEP communications occurred during 1957-1958 in the peak of sunspot cycle 19. Sunspot peaks in 1970 (cycle 20) and 1977 (cycle 21) expanded our knowledge of thei phenomenon.

When does TEP occur?

Two distinct types of TEP have been identified:

• those occuring during late afternoon and early evening, and usually over maximum distances of around 6000km. Contacts were restricted to the low VHF bands (6 metres for hams in most countries)
• those occuring around 1900 to 2300 local time, with workable contacts being made on 144MHZ(2 metres) and sometimes on 432MHz (70 centimetres)