HowTo PCB Patch-Antenna (EION model)

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Contents

Images

Antenna here is pointing down, the aluminium reflector is on the middle and the wifi equipment is the top board.
The shiny metal (RF) cable goes through a hole in the middle of the reflector, without any kind of solder but no isolation either.
The separators between the PCB and the reflector are made from a common kind of plastic transparent to 2.4ghz radiation.

Here you can see the measures of the square aluminium reflector (150 mm x 150 mm = 5.90 in x 5.90 in / 1.5 mm thickness) and the general overview of the antenna.

The PCB is also 1.5 mm thick, and the distance from the back side of the PCB to the aluminium reflector is exactly 19.3 mm (measured using a Vernier caliper)
The core of the RF cable is soldered to the front of the PCB (where you can see the center solder point) and the shield (mass) is soldered on the back side (Not visible here)

The solder point in the middle corresponds to the core of the RF cable. The little holes ("vias" - you can see one zoomed in) run through the PCB connecting with the circuit on the back.
Everything that might seem simetric, is. (ie. the upper and lower part of the central trace)

Cannibal-simulated view of the trace design on the back of the PCB. In this one, on the center you should solder the shield (mass) of the RF, and let pass through another "via" (hole, here covered by the solder) only the core of the cable, so that it can be soldered to the front circuit.

Finally, and as a useful gift, here you have a perfect design (in SVG format) ready for printing on A4 paper, with the exact millimetered measures, and all necessary details of the front and back sides of the PCB.

The author of this HowTo didn't actually try building this particular antenna, instead simply took detailed photos and measures. If anyone gives it a try, all contributions will be more than welcome.
Even without having built it, I had the opportunity to test the original one with exciting results. Sadly, I can't specify the real gain of the antenna, but a rural 8.5km link was made, between this one and a 9dbi antenna, both connected to EION 802.11b equipments, achieving a simmetric real 11mbits link (that is, 5 mbits of actual throughput transferring data = 640 KiB/s). The beam width seemed adequate, the antenna was pointed (at that 8.5km distance) holding with bare hands, with no help of binoculars or tripods, which shows a good performance and moderate gain.
The antenna has a vertical polarization when the PCB side that measures 123 mm stands perpendicular to the floor.
All the HowTo was made using free tools: Gimp for image treatment; Inkscape for creating from scratch the SVG design; (everything running on Kubuntu) Firefox for editing the MoinMoin wiki; and even a freely-borrowed screwdriver to dismount the antenna.