The KØNR Radio Site
Amateur radio operators on the VHF bands often use the Maidenhead Grid system for indicating their location. A grid is defined by 1° latitude by 2° longitude, measuring approximately 70 × 100 miles in the continental US. A grid is indicated by two letters (the field) and two numbers (the square). For example, the home location of KØNR is located in grid DM79, which includes greater Denver. Greater Colorado Springs is to the south in grid DM78.
These things are commonly called grid squares even though they are really rectangles or perhaps trapezoids. (Actually, since the earth's surface is curved, they are more complicated three dimensional shapes.) Anyway, I try not to say grid square, but it often sneaks in.
The most commonly used version of grid locator is
the 4-character version (e.g., DM79), which is used for the major VHF contests
and awards. Be aware that there is also 6-character version, which provides a
more precise location. The 6-digit locator is used in some contests including
the ARRL 10-GHz and Up Contest. The 6-character locater adds on two additional
characters to the 4-charater version, so they are consistent and compatible. For
example, my 4-character locator is DM79 and my 6-character locator is DM79nc.
We'll focus on the 4-character locator on this web page.
Map of VHF Grids in Colorado