Extending the range for a router/repeater

Why extend the range of the routers?

Hacked D-LINK
extended range router repeater 2012 030  rs

I am building the infrastructure of a network at a scoutcentre in Jutland.
It might sound like a trivial task, but money is severely limited and demand is high.
There are usually around 30 clients on the wireless net and around 60 when in peak periods.
This number will certainly rise as most young people are carrying smartphones at alle times.

The network so far consists of a wired backbone and a bunch of smaller wireless
repeater-islands for places where wired net is not feasible. These repeater-stations are, however placed where wireless does not have a direct line of sight, and the off-the-shelf routers cannot cope. New antennas with better rx-tx was needed.

The hardware

extended range router repeater 2012 010  rsD-Link before modding

The repeaters consists of a bunch of DD-WRT enabled routers of the cheap kind (D-LINK DIR 615 V.B1). They are configured as wireless bridged-repeaters and function quite well, except for the
fact that they have much too small antennas. Also, it is not possible to change the antennas on
the cheaper models. Now, the supplied antennas only have an amplification of 2db, which i deemed inadequate.
Therefore bought some RP-SMA connectors for box-mounting along with some nifty 12 db antennas.

It might sound as an easy hack to fix the RP-SMA connectors to the mainboard, but it is not.
The wires are REALLY thin, and you are working within a very small error margin.

Replacing the antennas

At my first attempt i tried to desolder the antenna cables at the mainboard and replace them
with some other that i could connect to the RP-SMA connectors. It did not work well. The industrial used to fuse the wire to the board are insanely hard and requires much more heat than a normal soldering iron can deliver. As a result i destroyed one router on that account due to prolonged overheating.

For the next router i chose another route - losening the cable in the antenna end. WAY better idea!
The cable is basically just losely stuck in the antenna and can just be pulled put.
Note the black lumbs on the cables. They are a noisefiltes and is supposed to be mounted as close to the antenna as possible. Luckily they can be shifted up and down on the cable and adjusted when the wires have been soldered to the RP-SMA connectors.

New unmodded router Router with antenna removed. Newly modded router

Note: It is NOT easy to solder this wire! I would not recommend it to people unfamiliar with a soldering iron.


The finished product

After soldering the wires and putting the router back together, a massive improvement could be noted. Unfortunately I do not have a precise measurements, but retransmissions (as measured by DD_WRT) went from an enormous count to negliable on the same link.

My bet is that a few of these and the will fix the situation. Two of them alone has done wonders :)