How to Find Your Own Grid Square
By Dave AD7DB
Revised June 17, 2002
- Step 1. Get your exact latitude and longitude, either in
degrees and minutes, or in decimal degrees out to
at least 3 digits.
- If you have a street address, look it up at
Eagle Geocode.
This seems to be limited to 100 searches, and of course it's for nonprofit/noncommercial use.
I'm sure, being the cheap hams we are, that we meet these criteria.
[This will open in a separate window so don't worry.]
- Mapblast.com
used to provide latitude and longitude, but stopped doing so.
- You can try the excellent online topo maps at
Topozone.
[Separate window.]
- You can use a commercial program such as the
DeLorme Street Atlas USA to find it.
- Or you can look it up the old fashioned way, on a regular topographic or navigational map.
- Or you can just go there yourself with a
GPS receiver
and see what it says. (Some GPS units will even tell you the grid coordinates directly;
if yours does, then you won't even need this page.)
- If all you need is the 4-digit grid number, the following will be
helpful:
- Step 2. Now visit
the ARRL website
or this site in the UK
to compute the grid square, using the latitude and longitude
you have for your QTH.
[This is also in a separate window.]
- Step 3. Write it down! That's what you need for exchanges with other hams.
Most hams are only concerned about the first four digits, such as
DM04. In microwave work or around the dense metro areas
the full six digits are useful,
since a four digit grid square (which is 2 degrees across and 1 degree high)
can cover a lot of area! My own is DM04se.
Regular grid maps can be seen
at the W6AMT page.
A detailed map of North America is available
over here.
You can even make your own maps at
WM7D's Map Generator.
There are a lot of different options available.
Here are a few samples of what you can produce there.
From these maps you can see that my home grid DM04 covers a large portion of
Los Angeles and Ventura Counties in California.
The intersection of four grids in the greater Los Angeles area is at
34°N and 118°W, which is in a sparsely populated area of
Turnbull Canyon
between Whittier and Hacienda Heights.
Notice that you can have distance rings, county and state boundaries plotted.
You can even include city names, which I turned off for this map
(it was getting a bit jumbled anyway).
Phoenix Arizona is bisected by DM33 and DM43 at 38th Street.
There are other major cities which span two or more grid squares.
(Very few hams live in DM19, as you can easily see.)
The third image is an azimuthal bearing map for the world based on
Los Angeles (34°N, 118°W). Madagascar covers 30° of radio horizon
from here. Most beam patterns aren't narrow enough for it to matter.
Reverse Lookup:
I haven't yet found a completely automated website
where you could plug in the grid square and produce a map centered on it.
(There ought to be one!)
But here's what I have found so far, just a couple of steps needed.
- Put in the grid here
and get the latitude and longitude.
- Then plug 'em in back at
Mapblast.
(Remember that West Longitude is minus!)
- This appears to produce a map based on the center of the specified grid.
You may have to zoom out a couple of levels to see where it is
in relation to everything else.
For more information about Maidenhead Grid Locator Squares
please visit the ARRL website.
Copyright © 1997-2001 David G. Bartholomew, AD7DB.
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