WiFi Radio Link

[Bob Proulx]

In the volunteer meeting Ian asked me to provide information about
this radio link project that I had described there.  I am NOT
proposing this as an identical solution.  This is just an example of
one thing that has been done.

At one time in the past I had set up a radio link for a WiFi network
connection from an office location across the runway at an airport to
the beacon tower where we had installed weather cameras.  The WiFi
link worked exceptionally well!  Really had no problems with the link
in all weather over about a ten year period of operation.

In 2012 I bought two 11db directional 2.4GHz antennas for $36 each.
These are small cubical plastic boxes containing a directional antenna
protected inside from the weather.  They are about twice as expensive
now.  It's a decade later.  In this case since the installation was
going to be static and point to point I just wanted to have a good
solid radio signal between the two points.  Doing this with a very
modest (11db) amount of directional antenna mostly made me feel good.

    
https://www.l-com.com/wireless-antenna-24-ghz-11-dbi-mast-mount-mini-panel-antenna-n-female-connector

They have an N-female connector (good quality high frequency
connector) on the back which is pretty standard for this type of RF
gear.  I mounted the antenna fairly high up the tower where it would
be above the metal hangar buildings and use a good quality outdoor
rated coax down the tower to the electrical box.

Here is a photo of this antenna pointing to the office.  Above are the
weather cameras that I also installed.  The weather cameras look out
at the horizon and view the sky above.  This is very useful pilot
information when flying into airports with weather in the vicinity.

    https://www.proulx.com/~bob/photo_album/2012-07-10-meadowlake-tower/15.html

The equipment to drive the connection was enclosed in a large steel
weatherproof enclosure box.  This connected to an adapter to the
RP-SMA on the back of a WRT54G.  Here is a photo.

    https://www.proulx.com/~bob/photo_album/2012-07-10-meadowlake-tower/11.html

We used a Linksys WRT54G of the old good version (which is now sold as
the gl version) with the Tomato free software firmware running upon
it.  I really liked Tomato but of course they have become moribund
now.  It was good then though.  For this particular hardware today I
would use DD-WRT now but at the time Tomato was current.

Actually these days I would use a small ARM single board computer and
run hostapd on the server and wpa_supplicant on the client for a full
free software stack.  It's ten years later now and though the best I
could come up with at the time was a WRT54G today there are better
options for the hardware.  Though the WRT54G being dedicated to the
task had no problems.

If someone were setting up a temporary router then either a laptop or
a small deskside would be good choices.  Anything today has more
processing power than needed.

I used a 2.4GHz system because at the time 5GHz was practically not
available.  These days I would definitely look at 5GHz.  It would
avoid a lot of noise interference possibilities on 2.4GHz.  But almost
anything in between blocks 5GHz such as trees or fountains.  I would
also look into using a USB WiFi Adapter for a second radio or for a
radio with an RF SMA connector to use with an antenna.  Those work
actually quite well.  There are only two vendors hardware which fully
support free software.  I have been using Mediatek WiFi adaptors most
recently.

We have another radio link that connects to a rural farm.  It
originates at a Remax office building with both a 2.4GHz and a 5GHz
flat directional antenna on the outside wall of the clock tower.  Then
it 3.8 miles to a windmill tower at Bill's farm.  Here is a photo of
me up this 32 foot ladder installing the antenna.

    https://www.proulx.com/~bob/photo_album/2012-09-16-radio-link/2.html

And here is a photo at the farm end.  (My blue Ford Explorer is what
hauled the boom lift around.)

    https://www.proulx.com/~bob/photo_album/2012-09-15-boom-lift/10.html

When we would get heavy rain or snow the 5GHz link would drop out.  So
we always kept the 2.4GHz link in place for fallback use.  It's always
good to have backup links.

Because of weather and various things I am up and down these towers as
required.  We don't usually have the boom lift and so I put on a
safety harness and climb the tower.

    https://www.proulx.com/~bob/photo_album/2015-04-12-tower/1.html

Sometimes things are just on top of roofs though and that makes
working on them much easier.  Here I am on top of the avionics shop at
FNL working on the weather cameras there.  It's a ladder to get up but
then you can just walk around up there.  Very hazy day with poor
visibility.  Can just barely make out the mountains behind that are
only 8 miles away.

    https://www.proulx.com/~bob/photo_album/2012-07-03-AvSpec-roof/3.html

And that's the stories!  Best though are the pictures! :-)

Bob