beam width math formula

[rpaquin]

ok, I didn't pay enough attention in geometry class.. I'll admit it, I was sleeping.

is there a simple formula out there.. if I have a 6.5 degree beam width, a 36 inch high antenna, with x amount of feet of distance, what will be my beam width, y.

any help cheerfully accepted (except on monday mornings!)

thanks!

[dixho]

You did not miss much in the Geometry class. A Geometry class does not help you to resolve the problem. You need to take at least 2 electromagnetic (EM) classes in Electrical/Electronic Engineering and possible a number of Calculus classes to figure out the answer.

Basically, you need to use Maxwell Equation to figure this out. Because Maxwell Equation is a partial differential equation, you need to take a number of Calculus to solve the problem.

I admit that I skipped most the second Electromagnet course(which covered Maxwell Equation) when I went to university. I forgot even how to model the antenna and translate it into a partial differential equation.

The easiest way is to get the antenna diagram from the manufacture. It saves to get study 4 years at University to resolve the problem.

Maybe, someone in the forum remember the EM and give you the answer of the partial differential equation.

P.S. The above is not writen on Monday morning. I am not sure if it makes a difference if it is a Monday morning or Tuesday afternoon.

[rpaquin]

actually, I'm wondering how accurate the following is..

BEAM WIDTH = ANGLE x .018 x DISTANCE

ANGLE X .018=Multiplication factor

BEAM WIDTH=MF x Distance

I found it doing some research at a lighting site, similar concept, they need to know coverage fields. Just visible vs non visible spectrum. I'm thinking it might be a good yardstick for coverage patterns.

ps. can be written any time, just nothing monday morning is favorable received, except blessed silence.