Antenna beamwidth? - RF Cafe Forums

The original RF Cafe Forums were shut down in late 2012 due to maintenance issues - primarily having to spend time purging garbage posts from the board. At some point I might start the RF Cafe Forums again if the phpBB software gets better at filtering spam.

Below are the old forum threads, including responses to the original posts.
-- Amateur Radio
-- Anecdotes, Gripes & Humor
-- Antennas
-- CAE, CAD, & Software
-- Circuits & Components
-- Employment & Interviews
 -- Miscellany
-- Swap Shop
-- Systems
-- Test & Measurement
-- Webmaster

Qacer
 Post subject: Antenna beamwidth?
Posted: Sat Feb 10, 2007 3:30 pm 
 
Captain

Joined: Sat Apr 23, 2005 2:09 pm
Posts: 17
Location: Tampa, FL
:-)

If I am given an antenna pattern plot that looks like this:


How would I estimate its beamwidth?

I was thinking that I find the point where the antenna shows the maximum gain and trace through the plot from one side finding the 3-db point and trace the opposite side finding another 3-db point. Is this correct? :?
 
   
 
nubbage
 Post subject:
Posted: Mon Feb 12, 2007 5:00 am 
 
General
User avatar

Joined: Fri Feb 17, 2006 12:07 pm
Posts: 218
Location: London UK
Yes, that is correct.
Some people quote the full side-to-side beamwidth as you describe, while others state the angle as +- x degrees, ie each side of the max gain direction.




Posted  11/12/2012