Some people have asked about my two tape
measure technique for laying out antennas.
Perhaps it would be useful if I posted a tutorial
to the reflector with the details.
Measure out 200 feet along the center of the
road using a tape measure and mark the ends
of this line. Now you have a N-S line 200
feet long (of course your road may be at a
different angle!). Now take TWO tape measures
(you must have two of them) and fasten the
end of tape measure #1 to the north end
of the 200 foot baseline and fasten the end
of tape measure #2 to the south end of the 200
foot baseline. Extend tape measure #1 to 200
feet walking straight west. Extend tape measure
#2 to 282.8 feet walking toward the west end
of tape measure #1. Now fine tune the angles
of the two tape measures until the ends meet.
Mark this point as 200 feet west of the north
end of the baseline. You now have 3 of the
4 corners of a 200 foot square. You can locate
the SW corner by measuring off 200 feet from the
NW and SE corners by using the two tape measures
to simultaneously measure 200 feet between the SW
and NW corner and the SW and SW corner. You
now have a 200 foot square. Any side of this
square can be used as a baseline to make an adjacent
square using the same technique.
An arbitrary location in a square can be located by
using the pythagorean formula to find its distance
from two square corners. The tape measures are then
used to simultaneously establish these distances, and
where the tape measures intersect, you mark the new
point. For example, the center of the square is 141.4
feet from any corner.
The "breakthrough" part of this technique, as it were,
is the simultaneous use of TWO tape measures. BTW,
you can get a good deal on tape measures from Harbor
Freight. (www.harborfreight.com).
Note: 282.8 feet is 200 times the square root of 2,
in case you were wondering where that number came from
(Pythagorean formula).
If your road is at an oddball angle, you can still
use this triangulation method, but you're going to
have to do a little trig to figure out the sides of
the first triangle you're going to layout. Can't get
into that kind of detail here.
Rick Karlquist
N6RK
> -----Original Message-----
> From: John Godwin [mailto:kb5iua@tgn.net]
> Sent: Tuesday, November 20, 2001 3:22 PM
> To: richard@karlquist.com
> Subject: Re:Laying out antennas
>
>
> Hello Richard
>
> I am a bit confused. Please help me out.
>
> "What I did on my 20 acres was to use two
> 300 foot tape measures to form triangles."
>
> How long are all three legs of the triangle?
>
> "I started with a base line down the center
> of the road (which runs within a degree of
> N-S) and then triangulated to a 300 foot
> line that was 200 feet inside my property."
>
> What do you mean by a '300 foot line'?
>
> "From this line, other lines can be formed
> by further triangulation establishing a
> grid of known points every 200 feet. Any
> subsequent point can then be plotted out
> by triangulation from the nearest 200 foot
> grid points."
>
>
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