Extending the NXT Wifi Sensor’s Range
The Dexter Industries Wifi Sensor allows your Lego Mindstorms NXT robots to connect to the internet and send and receive data via a local Wifi network. The I found that the Wifi Sensor had issues with signal levels, which is primary cause is my homes design. Laptops have issues as well in some areas as well.
Dexter Industries Wifi Sensor's U.FL connector
To get around this issue I needed to attach a 'High Gain Ariel' to the WiFi Sensor. The WiFi Module Dexter Industries chose to use has a U.FL connector on it. So a connector cable that interfaces U.FL RF connectors to regular SMA connections used by standard WiFi Aerials that attach to WiFi Routers, Modems and most PCI Cards.
U.FL to RP-SMA Ariel Connector Cable
I sourced a couple of 18cm UFL RF connectors to RP-SMA Ariel connector interfaces cables shown above for $2.50 off eBay. Most computer outlets should also have them. They attach to any standard RP-SMA 2.4GHz antenna used on DPAC 802.11 modules.
Technic Mount for Wifi Sensor to Ariel Connector Cable
The next issue was coming up with a universal mount for the Ariel that was solid and easy to connect to LEGO Technic components. After a little trial-and-error, I decided on modifying a Technic #32184, Axle and Pin Connector Perpendicular 3L with Center Pin Hole. The modifications to the Technic #32184 Connector was simply to drill out the centre hole with a 17/64 Drill Bit. The Ariel connection end of the fly-lead fits tightly into the enlarged hole. When the 2.4GHz 802.11 Ariel is screwed onto the fly -lead, the mount is very secure.
Using the Technic #32184, Axle and Pin Connector with Centre Pin Hole, allow a multitude of ways to fix the Ariel to your LEGO Mindstorms NXT Robot. The ExoForce Off-Road Rover: Mark II, shown below has the Ariel attached via 2x Technic #87083 (Axle 4 long with Stop) through the Ariel mount, via a chassis rail, and two Technic #32184 fitted on the protruding shaft to lock the Ariel into place.
With the new 9dB Wi-Fi (Signal Booster) Ariel attached to the Dexter Industries Wifi Sensor, I can now send and receive data over my local Wifi network in any direction, for a radius of 80-100m.
I advice you too unscrew the Ariel from the fly-lead when not in use, but have the other end permanently attached to the Dexter Industries Wifi Sensor. Care must be taken with the fly-lead attachment on the WiFi Module. I suggest that you feed the Fly-lead through the hole in the centre of the WiFi Sensor's PCB. This will help to secure the the Fly-lead and protect the WiFi Modules tiny Ariel Socket.