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seagreen
Mod
join:2001-05-14
out there

seagreen

Mod

Forum FAQ - pending feedback...

For this item: »Wireless ISP FAQ »How is antenna gain (dBi) measured and used?
said by feedback :
please provide with the formula to calculate the gain of the antenna in dBi .....
Anybody have this formula so it can be added to the FAQ?
LLigetfa
join:2006-05-15
Fort Frances, ON

LLigetfa

Member

IMHO there is no simple formula that an end user could use. That is in the domain of antenna design modelling software. For more info see:
»www.si-list.net/swindex.html

P.S. The topic is too detailed to fit within the limited scope of a FAQ.

John Galt6
Forward, March
Premium Member
join:2004-09-30
Happy Camp

John Galt6 to seagreen

Premium Member

to seagreen
Make reference to this document:

»arxiv.org/PS_cache/physi ··· 23v1.pdf
lutful
... of ideas
Premium Member
join:2005-06-16
Ottawa, ON

1 edit

lutful

Premium Member

The classic W1GHZ antenna design handbook ( »www.qsl.net/n1bwt/contents.htm ) provides gain theory and calculation for many antenna types used by WISPs.

seagreen
Mod
join:2001-05-14
out there

seagreen to John Galt6

Mod

to John Galt6
said by John Galt6:

Make reference to this document:
Yikes - I haven't seen stuff like that since calculus in college. *shudders*

I'll probably just link the responses in this thread to that FAQ item.

Killer Max
@rr.com

Killer Max to seagreen

Anon

to seagreen
said by seagreen:

please provide with the formula to calculate the gain of the antenna in dBi ...
Not sure that is even a valid question. The gain of an antenna is a factor of it's physical construction, and not something that would be deduced by a mathematical formula. The amount of gain and the shape of the envelope are factors of reflective surface area and it's relative angles, active element characteristics, apex distances and etc. There are certainly formulas used at the manufacturing level as guides for a new design, but the actual gain of an antenna is authoratively determined by radiation pattern measurements in a laboratory environment. If the question was actually "What is the formula to determine the difference between DBi and DBd", the answer is add 2.2 to the DBi value.

seagreen
Mod
join:2001-05-14
out there

1 edit

seagreen

Mod

That wasn't my question but rather feedback left in the FAQ....

I kinda figured it wasn't going to have a simple answer and since I don't what the intent was of the person who asked I thought I'd throw it out to you guys to talk over.