In article , Rick Hughes
scribeth thus
On 01/06/2014 11:45, Tim Watts wrote:
And if you wanted to add a remote antenna on a lead (for better antenna
placement), can you just add one and does it matter which of the 2 or 3
sockets you connect it to?

Could you even add 2 or 3 external antennae to the same unit?

Never understood this...


Some access points have 2 identical antennaes to provide diversity and
hopefully better Tx/Rx throughput,

Diversity is what is required this isn't a simple point to point link
environment.. Plane polarisation also gets badly skewed what starts as
Vertical is rarely that when it gets to where its required.


others (I have one) have 3 antennaes
and the '3rd' uses different frequency.
For optimum efficiency antennas have to be matched to wavelength ... so
if you have 2 specific frequencies one (usually best) option is a 2
matched antennae.

Although most cheaper access points just have one of more antennae
matched to a single frequency.

Around mid of the band of interest ..

If you want to remote off an antennae ... you can do this as long as you
use correct impedance matched cable, and you either use a physical
ground plane, or a wire wound groundplane mimic.
If you don't know how important a ground plane is ... here is another
page for you:
http://en.wikipedia.org/wiki/Ground_plane

Even 2 strips of adhesive backed thick aluminium tape in a 'cross' with
antennae in middle can be good enough.
(often used on fibreglass structures)


It can be better than nothing on vehicle roof's for VHF frequencies but
nowhere near as good as metal sheet..


--
Tony Sayer