Marlborough Wi-Fi

RooTenna and RouterBOARD installation

I had my first go with a low-profile 5GHz Rootenna from Pacific Wireless today. The Rootenna is a panel antenna designed to accommodate electronics as well so you can have a completely integrated unit.

I thought I’d throw a RouterBOARD 532 inside and be done but found there was a bit more involved than what I originally expected (next time I’ll be getting the full-size version). Because of this I thought I’d share how I went about things in case anyone else runs into the same problem. I have also made a scale drilling template available.

A note to anyone planning on using a RouterBOARD 100 series in one of these; order the full size version! The filter capacitors on the board are much taller than on the 500 and therefore will not fit in the low profile version.

The first impressions of the Rootenna were that although it looks a bit tacky, it seems to be fairly well-built. The backplate is aluminium and all fasteners are stainless steel. The mounting bracket is galvanised steel and past experience has shown that these hold up well to corrosion over the years. The radome is made of thick ABS plastic and the sealing gasket appears to be very adequate.

Note there are small drain holes near the cable entry hole, so the antenna must be mounted with these at the bottom.

Inside is where the fun starts. For some reason (most probably to simplify manufacturing), the SMA antenna connector is mounted right in the centre of the panel. Although the shipped pigtail features a right-angle SMA connector, there is very little clearance between this and the backplate. There are stand-offs inside for attaching equipment or a mounting plate (not included), but if using a plate you would have to drill a hole in the middle for the connector to fit through. The end result is while there is technically tons of room in the case, you don’t get to use it very effectively as everything needs to fit around the connector.

After experimenting and head scratching I figured that the RB532 would fit if mounted face-down to the inside, with the SMA connector a few millimetres from a blank area of the RouterBOARD PCB where the LED connector would normally sit. This means the board needs to be mounted to the backplate, and that means making holes on the outside of the Rootenna. I was trying to avoid that as it means greater possibility of leaks but in the end if it is sealed properly then this shouldn’t be a problem.

I’ve made a drilling pattern for the backplate that you can find here. You will need to use nice short M3 screws and 6mm threaded spacers. Anything longer will cause the SMA connector to foul the board. Use stainless screws and small rubber washers to seal the outside screws or alternatively you could smear silicon-based sealant over the outside screw heads.

The bottom mini-PCI slot sits almost touching the backplate so I placed some PVC tape over the backplate to prevent shorting.

With the RouterBOARD in place, you can see there is not much room. I’ve also placed some more tape over the LED connector area in case the SMA connector contacts any part of the RouterBOARD PCB.

I installed a Pacific Wireless sealed RJ45 connector to save having to open the Rootenna when installing or removing on site. These have received some bad reviews on the web but I find they work very well when used with outdoor rated Cat 5/6 cable.

The grounding strap included with the Rootenna (thats the random metal strip included but not mentioned in the instructions) can be mounted to one of the internal stand-offs using a short 1/4″ thread screw. Sandwhich the strap between two washers to ensure it stays secure and creates a good electrical connection. Check that it does not touch the RouterBOARD when assembling the Rootenna, but should make good contact with the backplate.

The assembled unit looks quite tidy and works very well. I’m glad the weatherproof RJ45 connectors do the trick as dismantling one of these on site would be quite a pain given the way things are crammed in there. I’ll get some antenna performance figures later to compare it with a parabolic grid of similar gain.

While the low-profile version is probably perfect for small access points, I’d recommend ordering the full-size version just in case as the position of the SMA connector really is quite awkward. I’d also be happy to pay a little extra for a mounting plate and screws to be included as having a complete kit is much more convenient than having to spend time making extra parts myself.

This entry was posted on Thursday, March 16th, 2006 at 16:06 NZDT and is filed under Projects & Experiments. It has been viewed 5423 times. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.