A vertical rod about 4' long (plumb it, or use a level) will have the shortest shadow at noon.
I should have said "near noon".....
Not necessarily. Ignoring DST, local solar noon can occur anywhere within a window of around 1 hour (give or take, depending on the exact borders of your local time zone), because each time zone is approximately 15 degrees wide (there are local variations that take the official zones beyond the 15 degree nominal zones). For example, here in Melbourne, local solar noon usually occurs around approximately 02:15 - 02:20 UTC (12:15 - 12:20 standard time or 13:15 - 13:20 DST). In Brisbane, it occurs before noon AEST, despite both cities being in the same time zone. Using the "shortest shadow at noon" method, you can have an error of up to 10 degrees (now THAT would ruin the performance of your high gain antenna!). Here, it would be around 4-5 degrees, if one was ignorant of the actual time of solar noon.
The moving shadow to find the East - West line is a much better and MUCH more accurate idea.
73 de VK3JED http://vkradio.com
73, Dave, WB6LLO dguimon1@san.rr.com
Disagree: I learn....
Pulling for P3E...