Trans-Equatorial Propagation (TEP)

 

                                        https://ei7gl.blogspot.com/2024/04/first-ever-tep-contacts-made-at-144-mhz.html?s=08

 Trans-Equatorial Propagation (TEP) is a phenomenon in radio wave propagation that occurs between two regions located on opposite sides of the Earth's equator. It involves the propagation of radio waves from one hemisphere to the other by utilizing the Earth's ionosphere, particularly the F2 layer.

Here's how TEP works:

1.  Ionospheric Reflection: Radio waves transmitted from one region travel upward into the ionosphere, where they encounter the F2 layer. The F2 layer is the highest layer of the ionosphere, located at an altitude of approximately 200 to 600 kilometers (124 to 373 miles) above the Earth's surface.

2.  Refraction and Reflection: When radio waves encounter the F2 layer, they can undergo refraction and reflection. Refraction occurs when radio waves bend as they pass through the ionosphere, while reflection occurs when radio waves are reflected back toward the Earth's surface by the ionosphere.

3.  Equatorial Crossing: In TEP, radio waves that are reflected or refracted by the F2 layer can cross the equator and propagate into the opposite hemisphere. This crossing typically occurs near the magnetic equator, where the Earth's magnetic field lines are nearly horizontal and facilitate the propagation of radio waves between hemispheres.

4.  Reception: Once the radio waves have crossed the equator, they continue to propagate in the opposite hemisphere and can be received by radio operators located in that region. This allows for long-distance communication between stations located in different hemispheres, often spanning thousands of kilometers.

 Trans-Equatorial Propagation (TEP) is most commonly observed on the 10-meter amateur radio band (28 MHz) and is favored by high solar activity and geomagnetic disturbances, which enhance ionospheric conditions. While TEP can provide exciting opportunities for long-distance communication, it is also subject to variations in ionospheric conditions and is not always predictable. Amateur radio operators often monitor the 10-meter band for TEP openings, particularly during periods of enhanced solar activity, to take advantage of this unique propagation mode.