Range-Test with two biquad antennas - 2.5km range

[Tasm-Devil]

Hello,

I'm Pascal from Germany and today a tried to figure out the maximum distance, I can get with biquad antennas connected to two moteinos.
The basestation mote is mounted on the back of a 35 mm x 35 mm Perspex pane. Aluminium foil is glued on the front side as a reflector.
The second node has a omnidirectional biquad antenna. I use SMA connectors and an SMA to U.FL pigtail to connect the antenna to the moteino.
The 2 mm copper wire was 8 x 83,7 mm (868 MHz) long so its total length is two wavelength. Here is the formula including the velocity factor:
http://www.wolframalpha.com/input/?i=2997924*0.97%2F%28+4+*+868+%29%29%2F10

In my experiment today I established a 2,5 km line of sight connection! This was the maximum distance I could test. I used an LED-array to display if the last 8 acknowledges are received.
Here are some pictures:
http://deneaux.de/store/Forums/lowpowerlab/biquad1.jpg
http://deneaux.de/store/Forums/lowpowerlab/biquad2.jpg
http://deneaux.de/store/Forums/lowpowerlab/biquad3.jpg
http://deneaux.de/store/Forums/lowpowerlab/biquad4.jpg
http://deneaux.de/store/Forums/lowpowerlab/biquad5.jpg

I am interested in your estimation.

Edit by Felix - added photos from Flickr:

[Felix]

Very nice work!
Others have gotten similar range results with improved antennas.
I am wondering about a few things:
- Did you do any temperature compensation?
- What were your bitrate/BW settings? Any possibility to share your register configuration/code?

With your permission I would like to include your pictures in my Moteino-projects Flickr pool and include them in this post.