43.33
Km LOS with USB WiFi stick
Is it possible?
Hard to say, so before
attending the real location some calculation with the help of the software is
essential. Curiosity was the main reason, and if there is just a marginal
possibility it's worth to give a try. All experiments and measurements are done
randomly without notices to any parties to scan the real situation on the
field.
As you can find out from the
software calculation, radio link between two identical WiFi stations is
possible with the standard equipment. In this case standard means cheap, easy
available WiFi equipment with following characteristics:
TX power : 0,02 W
RX sensitivity : 5uV (-93
dBm)
Antenna gain : 15dBi
Line loss : 1dB
Propagation over the water,
continental temperature and some other details not visible on the picture are
also considered. For the antenna height I chose 5m as average on both sides.
Limited with already
mentioned parameters, the only factor that we can play around is location of
the antenna-equipment. I choose the hill 250 meters ASL with clear horizons to
Line Of Sight is essential in
this case, clear sky, nice weather and we are ready to roll. Distance between
my location and
WiFi equipment used on my
side was really marginal. RF hardware - Simple USB 802.11b WiFi adapter with
original antenna. Whole adapter was mounted in the focus of the Deep Dish
Cylindrical Parabolic antenna. The design found on the web was easy to build
(copy). As this is just quick and dirty approach, whole antenna was ready in 30
minutes. Aluminum food foil, hard paper, polystyrene, scotch tape and the
cutter is all you need to fabricate this antenna. Looks too simple to work,
produce some gain, but I was surprised with the results I get. Many people
already experienced same results but this antenna just overcame all my
expectations. The real gain was not measured but simple comparing this antenna
with the barefoot USB adapter in the local city network was good enough to take
this ''State of art'' on the remote location. Just to mention that signal level
jump from poor 20% to good stable 40% with this antenna. IT hardware – 5 meters
of the USB connection cable ant notebook.
Aftermath showed that WiFi
equipment used on the other side was not a ''Rocket science'', antenna sector
15dBi, AP senao 3054cb3 (PrismGT chipset 802.11g). The fact that the sector
antenna was not pointed in my direction give us a plenty room for better signals
on both sides.
After the initial Site
Survey, immediately pops up the SSID on the Ch 5 with 20% of signal level.
Attempt to point my antenna more accurately did not give me better signal that
20% from the initial try. Considering all before mentioned facts this was good
enough for me. Calculated distance between this to sites is 43.33 km. Cost of
wireless equipment used on my side together with 5m of USB cable is 26 Euro. Calculation
gives us funny ratio of 60 Eurocents/km.
Any questions, feel free to
contact me on
