[MLB-WIRELESS] Antenna heights ... what's your practical experience like?

Tyson Clugg tyson at melbournewireless.org.au
Mon Oct 31 14:28:33 EST 2011


Hi Greg et al,

2011/10/31 Greg McLennan <mclennan at internode.on.net>

>  Hi David.
>
> I'v had good experience using http://www.ubnt.com/airlink/
> for height calculations(try IE and or Firefox, is a bit buggy sometimes).
> I'm running a 6Km link @ 2.4GHz with a small hill around the 3km mark that
> I needed to get over, and comparing heights from the program to actual
> physical install was well with a meter for my experience.
>
> I did note for the install however that 2.4GHz worked well, yet @ 5.8GHz
> for the same link and height antenna I could not establish a link.(I
> physically could not go higher). I could see stations at 5.8GHz that were
> further away than my intended sites from both points!. 2.4GHz (-69dBm), yet
> 5.8(same gain antenna 25dBm & tx-power) could not even site the remote
> ap(weird!!)...
>

Be careful with the Ubiquiti settings - if you leave AirMax enabled on
AirMax capable devices (the first settings tab in the web interface, no tab
name just the Ubiquiti logo) then only other devices with AirMax enabled
will be able to see your AP.  Disable AirMax and try again.  ;-)

So I'm new to this game, and I'm looking to setup a link between two houses
> that are just shy of 2km LOS from each other.
>
>  I know I can find equipment that'll span this sort of distance without
> any problems at all, but my main concern now how high I'll have to mount
> everything in order to get a decent signal?!?
>
>  The terrain is close enough to dead flat, but given that both houses are
> only single story, I'm not really sure exactly where I stand on this front?
>
>  Does anybody have any practical experience / advice / rules of thumb for
> this sort of scenario?
>
> Suck it and see.

>  Is there any particular equipment that I should be looking for [or
> looking to avoid] with this setup?
>
> I prefer the Ubiquiti equipment too: weatherproof AP + integrated antenna
+ power over ethernet = zero cable loss, better radio signal management
(especially with multi-polarity integrated antenna systems), significantly
less things that can go wrong, and significantly cheaper than buying all
the components (antenna, coax, pigtail, mounting box) separately.

The software seems half decent as well, though the stock firmware doesn't
run OSPF (eg: quagga).  Not that I need it, instead I plug the other end of
the Cat-5 from my Ubiquiti devices into something like the Asus WL500GP
with it's built in 5 port VLAN tagging switch running OSPF on
OpenWRT/DD-WRT/Tomato firmware.  Everything is low power, there's only one
place to configure/break/fix the OSPF configs, and I can add links to
multiple nodes with decent performance.

> I'd really appreciate any help / advice / suggestions you might be able to
> give me ...
>
> Be good to your mother?  :-P

Cheers,
Tyson.
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