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Homebrew parabolic antenna

Homebrew parabolic antenna

My design goals were to be lightweight, durable, reasonably easy to make and of course work effectively. I decided to over engineer a solution and this is what I came up with. First, I built a frame out of mild steel welding rods, these were gas welded to produce the basic antenna shape.
I needed to provide my own dipole assembly and had two options in mind. Either arrange for the original Linksys antenna to be mounted in the focal point of the parabolic dish or make my own dipole. I didn’t have a RP-TNC connector to hand so I opted for the “make my own”. I wanted to be able to tune the focal point so soldered a piece of brass tube into the dipole support plate (technical term for a bit of tin plate!) It doesn’t matter what size tubing you use, I happened to have some K&S tubing from a modelling suppliers and by combining this with some slightly smaller tubing arranged a “trombone” fitting so that the inner tube could be moved in and out to find the focal point. I happened to use 11/32nd and 5/16th tubing.

The reflector was made out of aluminium mesh, the type you repair car bodywork with as a support for body filler. It’s soft and easy to bend around the frame. I just fixed it to the frame with small bits of wire which I twisted to keep it secure.

Now for the dipole. I applied very little skill here, radio-hams might cringe but again, this was a quickie solution rather than an overly technical one. I just needed to meet the design goal, I didn’t need to achieve anything more. The dipole is simply made from two pieces of 30.5mm brass tubing soldered to the coax which comes through the dipole assembly tube. Strip the coax a short amount and attach one tube to the centre core and one to the braid.

To compare the antenna against a cantenna design, it’s much much more directional. Cantenna’s can be aimed anywhere roughly in the right direction and will immediately start to work, the parabolic dish snaps in at the right point but is pretty weak otherwise.

From my limited testing the gain seems to be about 2dB greater than the cantenna although in order to connect my parabolic antenna to the laptop, I had to use a couple of adaptors and a pigtail to the Orinoco so it’s quite possible that the signal might be a total of 3dB greater, which of course, is double the signal! In terms of difficulty to build, as I said, I over-engineered a solution, Michaels template can be made of out foil covered card like I used for the cardboard horn antenna and thus can be made in about 10 minutes too.

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