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Yagi antenna - number of elements?

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daniel488

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Hi,

could You tell me if FCC has some rules about number of Yagi antenna's elements. I found on some producer website an information that it is not permitted to use Yagi with 13 elements and something about gain (i don't remember this site and can't find it again). I tried to find this regulations on FCC site but I can't. Could You help me?
 

you need to be a bit more specific about what frequency band you are referring to
are you referring to receive and transmit ??
possibly WIFI and UHF CB radio have maximum EIRP limits and that would limit the
gain (size) of a yagi for that particular band

in general no there are no restrictions on number of elements on a yagi
the restrictions are more a physical thing eg.

say on 7MHz (amateur 40m Band) a 3 element yagi is physically huge!!!

but on 1296MHz (amateur 23cm band) my 23 element yagi is physically small
on a 2.5 metre boom and if I was keen enough I could phase 4 of those yagi's
and have almost 100 elements total. no restrictions there :D

cheers
Dave
VK2TDN
 

I don’t think FCC has requirements regarding the number of elements of a directive antenna. Generally they have requirements for gain or ERP, which is indirectly affected by the number of the elements.

Number of the elements is direct proportional with the antenna gain (or ERP) only if the antenna is well designed.

If is a crappy antenna you could have less gain with 10 elements than using 5 elements. Just dropping elements on the boom of a Yagi, without any calculation or simulation, is not getting any gain improvement.
 

I'm looking for 902 - 928 MHz antenna with gain about 13dBi but could be a little less. More important is -3dB beamwidth than gain, it must be minimum 50 - 60° in E and H planes.
When I read this restriction on that aforesaid website that was strange for me too and I would like to have some confirmation that FCC hasn't this kind of rule.
So I think the most important for me are: maximum power 30 dBm, maximum gain 6 dBi, EIRP 36 dBm and every corrections of power if my gain is bigger.
 
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