Hi,

I had designed an aperture coupled patch array antenna. I am looking for an easy, quick enclosure for this antenna so that I could mount it outside, open to the environment. The antenna is about 60cm long, 6 cm wide and about a couple of cm deep. Any suggestions? I dont want to spend too much time designing an enclosure. I'm essentially looking for a quick fix solution.

Thanks!!

Karthik

My approach has been to locate a scrap plastic seedling tray from garden center purchases visits, line it with thin polythene film, place the assembly inside it and then foam in place either polystyrene packing foam or polyurethane insulation foam. Remove the seedling tray and thin polythene film when the curing process is complete.

Both materials are low loss up to 12GHz, and are fairly imune to UV. Birds will eventually peck most of it away but you have probably 5 years of cheap simple weather enclosure service from this method.

Hi Nubbage,

Thanks for the suggestion. But wont polystyrene get damaged in rain/snow? If I've understood you correct, polystyrene would be exposed to the environment.

Hi Karthik
No, if you buy the higher density foams, they are fairly resistant to ice and snow.
To improve water protection, a thin coat of polyurethane varnish seals the outer layer of cells. Because the cell structure is closed, water ingress should not be a problem.
The biggest risk is cracking due to wind pressure distortion, but the mechanical strength of the metalic parts should take care that no stress passes to the plastic foam.

Hi Nubbage,

Wind load was another issue I had in mind. At present, I've just got two PCBs held in place by spacers. I dont have a metallic part to provide mechanical stability. I was in two minds about adding a metallic back plate to the antennas. I think I should add the back plate. I was thinking in terms of a molded ABS plastic cover sort of thing which will enclose the antenna. But havent been able to find a readymade solution for this size. I guess your idea would be the quickest fix. I've never done garden center shopping, but I did look online for the plastic seedling tray. I think I need to have it in front of me to really get a good grasp of your idea!!

Hi Karthik
Three points I would advise on
1) definitely use the backing plate. Aluminum plate about 0.25 inch thick for mounting the boards on, and that gives a firm platform for the mast clamp.
2) avoid ABS: the loss at microwave frequencies can be significant. If you must use it, try the microwave oven test before you do. It is not necessarily the ABS, but the plasticisers they use, and these change with manufacturers so it is difficult to define exactly.
3) Imagine the seedling tray as a large pie baking dish, shallow but deep enough for the boards and backing plate, and with sloping sides.

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