A
point-to-point Wireless Solution for
CAT5-based Internet connectivity
This article presents a wireless solution
that is a ‘Commercial Off the Shelf’ (COTS) arrangement.
At our home QTH, a solution needed to be
found for providing internet connectivity to our COMVAN,
which is usually parked behind our home when not in use (actually, it is parked
behind our house
most of the time even when it *is* in use).
Using a PCMCIA Netgear wireless card in this
particular application proved useless, as the laptop
PC is inside of a metal communications shelter, and even with the door of the
shelter opened,
connectivity was very spotty even though the RF path length is only 75 feet.
It is clearly
obvious that the internal patch antenna of this wireless card will not provide
the needed
connectivity to the wireless LAN in our home.
Below is a photo of the prior effort at
wireless connectivity to our
wireless LAN from our comvan:
Running a length of CAT5 or CAT6 Ethernet
cable to the vehicle seemed a “logical” solution
except that such a run of cable would end up being directly underneath a
120-foot,
HF multi-band dipole antenna which is strung diagonally across our property, at
a height of
about 15 feet.
Solving complex RFI problems in the past
usually required the equivalent of some heavy voodoo
or other form of magic in order to eliminate such RF interference. Given this
experience, the
thought of running 75 feet of CAT5 cable from our house to the comvan
did not seem to be the best idea to pursue.
The solution in this case was the
use of high-gain directional antennas at each
end of a wireless connection path, and the use of two NetGear WG102 wireless access
points
which are configured in “bridge mode”.
"Bridge mode" in the usual sense, is for the
purpose of connecting two separate
local area networks together so that any pc in one network can access resources
on the other. "Bridge mode" essentially is a dedicated point to point link,
where only
two MAC addresses are used. Each access point has it's own internal MAC address,
and as part of the bridge-mode configuration, also has the MAC address of the
access
point
it is pointing towards configured in its setup.
In this mode, such a link will appear to the
"far-end user" (in this case the notebook pc
within the comvan) connected to the Internet via a CAT5 Ethernet
cable.
A real benefit of using Netgear products is
that many of their devices are designed to be powered
from a 12 volt-DC source, and is usually supplied via a wall-wart. In a vehicular
environment,
what could be
better than equipment that can be plugged directly into an Anderson Powerpole
strip??
As cable losses at 2.4 GHz can be huge when
long lengths of cable are used, this solution
required only 2-feet of antenna cable from the access point in our front room,
to a Hawking
corner reflector antenna having 15 dBi gain, and only a three foot RF cable from
the access
point in the comvan to a model WAN2218, 18 dBi enclosed Yagi antenna which is
made by a company called “Level one”
Level One WAN2218 Antenna mounted to our
COMVAN. This radome-enclosed multi-element yagi
antenna is just over four feet in length. It is installed directly
adjacent to the comvan's cable entry panel:
View of the WG102 Access point, connected up
in our COMVAN and located directly in front of the cable
entry panel:
Below is the indoor-end of this wireless
link, consisting of
a Hawking Corner reflector, installed in our
living room,
and connected to the indoor Netgear access point.
A CAT5 cable then connects the access point to a
Linksys DSL modem's internal Ethernet router:
Below are front and rear views of the
WG102 Access point
An additional advantage of CAT5 connectivity
from the comvan's notebook
PC is that the PCMCIA card slot is now available for a card which allows
for two additional USB 2.0 ports that are connected to the notebook's
internal card bus:
Shown below is the use of a USB2.0 port via
the new card
for use via the MIXW soundcard software in which the digital
data is sent to a Tigertronics SignaLinkUSB interface, and
then connected to a Yaesu FT897D via the data port on the
back of the radio:
Below are links to the information on the
access
point and the antennas
Netgear WG102 Access Point:
http://tinyurl.com/wg102
Hawking HAI15SC corner reflector antenna:
http://tinyurl.com/hai15sc
Level One, WAN-2218 Antenna:
http://tinyurl.com/ld9q3l
