During the daytime, medium and high-powered mediumwave AM radio stations have a normal reception range of about 20 to 250 miles (32 to 400+ km), depending on the transmitter power, location, and the quality of the receiving equipment, including the amount of man-made and natural electromagnetic noise present.
Long-distance reception is normally impeded by the D layer of the ionosphere, which during the daylight hours absorbs signals in the mediumwave range.
Some of these operate with over 100 kW of power with highly directional antennae aimed northward to avoid interfering in the rest of Mexico.
These stations typically run at very low powers (limited to 10 watts) and are only intended to cover small areas, but may travel thousands of miles under certain instances.
The Pacific Coast of the US provides a similar opportunity with stations from Asian countries and Australia / New Zealand although a considerably longer distance must be covered.
On both coasts, as well as in the middle portion of the country, "Pan-American" DX from Latin American and Caribbean nations is often sought and logged.
The wide variety of languages spoken over the DX'ing range, from Spanish to Arabic, adds an element of challenge to DXing in the region.
In the southern half of the China, Japan, Korea(both south and north) and Taiwan stations, some of which operate with over 200 kW of power, may be heard on a similar night-to-night basis.
More serious DXers may spend much more for a tabletop shortwave communications receiver with good performance on the lower mediumwave frequencies using an external antenna, such as the AOR 7030+, Drake R8/R8A/R8B, Icom R-75, or Palstar R-30.
[2] Radios like the Microtelecom Perseus[3] and the Elad FDM-S2[4] can record the entire mediumwave band to a computer hard drive, which can then be played back and tuned later.
In order to cancel out reception of unwanted stations, some DX listeners employ elaborate phased arrays of multiple Beverage antennas.