# How to plot horn antenna radiation pattern?

#### boablahuj

Joined Mar 3, 2016
14
My task is to plot horn antenna radiation pattern. I'm using this book as a reference. I've already calculated values below:

Explanation on the picture what is what:

Also, I've been given frequency f = 9.8GHz. My problem is, I don't know how to plot radiation pattern to look something like this:

I'm not sure how to obtain necessary values to plot graph like this one above.

#### MrAl

Joined Jun 17, 2014
7,590
Hi,

I think the way to do this is to use your formula to project the radiation energy onto a spherical or semi spherical surface and then plot the energies found at that surface. The spherical surface is a surface that is centered at your source, and i guess you'd have to determine where you want that to be too. If the distance to the surface is large then it wont matter where the center is as much, but if close by (dish) it would also depend on that too. So the plot comes from each point being projected individually and since that plot is not three dimensional then you must be assuming some symmetry because if you dont have symmetry between two dimensions then you'd have to do a three dimensional plot, which you dont seem to have to do.

We talked about something like this for a 'regular' RF antenna not that long ago in another thread. Not sure where that is right now though.
Not sure if i will get a chance to read your book, but maybe someone else here can.

#### art21

Joined May 11, 2017
1
You need to calculate the E-field at the aperture (TE10 mode), and then calculate the far-field pattern using the Equivalence principle.
If you want to check the validity of your results, yo can use this online calculator:

http://hornantennacalculator.blogspot.com