[OpenWrt-Devel] Dual Wifi for OpenWRT

David Lang david at lang.hm
Sat Jan 10 16:05:34 EST 2015

On Sat, 10 Jan 2015, Bruno Randolf wrote:

> On 01/10/2015 08:38 PM, David Lang wrote:
>> I would not expect to find consumer hardware that had two radios on the
>> 2.4GHz band, the problems that you would run into trying to keep the
>> output of one radio from deafening the other (if not outright popping
>> the receiver amps) would be significant (to say the least). It could be
>> done, but it would take antenna setups that you just don't see mass
>> produced to even get started.
> Right, that is a good explanation why no consumer HW with this feature
> exists.
>> Even the "enterprise" grade hardware that has multiple radios tends to
>> have problems with this. It takes having very directional antennas to
>> try and keep as much of the signal away from the other radio to even start.
> Hmm... Yes antenna placement is important and difficult, but I know
> setups where this works quite well. E.g. using RouterStation Pro with 3
> MiniPCI cards (ath5k/ath9k).
>> What is it that you are trying to accomplish?
> For one part I'm trying to find alternatives to that RouterStationPro
> board which is EOL.
> But in the current case I actually want to have one or more radios in
> monitor mode (running "horst", switching thru channels) and another one
> for connectivity (mesh). In this case the interference problems you
> mention don't exist, but I admit that this is not a very usual
> use-case... ;)

In that case you re probably best off adding a USB wifi interface to a router.

In terms of antennas, try going with high-gain omnidirectional antennas and 
position them directly above each other (omnidirectional antennas have a 'blind 
spot' directly above and below the antenna, so if you position them so that each 
is in the blind spot of the other you have the best chance of it working, and 
high gain antennas are going to have flatter patterns, making them more 

David Lang
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