Tushar;

First of all, thank you very much for replying.

I have taken a series of RF field strength measurements of an FM
transmitter, traveling around (360 degrees) the antenna (on the available
dirt or paved farm roads) with a radius from .8 to about 2.3 miles from the
FM antenna tower. I had a GPS reciever which stored the Latitude and
Longitude at each measurement point being sampled each second along with the
signal strength using a calibrated FM receive antenna, in a text file (I
also took GPS measurements of the tower location to use as the center point
for my graphs). I have a program which plots the location, on Microsoft
MapPoint, the field strength measured, with colored dots, each color
representing a small range of the minimum to maximum of the measured RF
Field strength.

In order to get a better visual representation, I would like to plot the
Lat/Long points in Polar form on an XY graph, so I would have a point at the
end of each ray, using the co-ordinates at the FM tower as the reference or
zero point.

I could then use a simple formula to calculate, from the known distance (r)
from the tower and the measured signal strength, what the strength would be
at, say, a 1 mile radius for all the rays, then convert THAT result to a
colored dot on a Polar or XY (with positive AND negative values) and get a
much better visualization of any anomaly or directivity of the transmitting
FM antenna. I have looked through the help files, tried Cartisian formulas
(which don't seem to care for negative values of X) as well as through this
and other news groups, but haven't been able to find anything close enough
to work. Unfortunately, I am not a math wizzard, and I haven't really done
much charting (most of which I have given up on). However I really need to
see this one through.

Thanks again for your time, and I hope this gives you a little better
understanding of what it is I am trying to accomplish.

Regards, Dave Whitehead