Wednesday, October 04, 2006

Making the double biquad

I had some time last night, so I decided to make the actual double biquad part of the antenna. As I said in a recent posting, I used the ground wire from standard household electrical wiring. I used a permanent marker (the kind used to write on recordable cds) to mark out the location of the various bends. According the what I found online, each side of the "diamonds" should be as close to 30.5mm as possible.

At first, I tried using two pairs of pliers to make the bends as sharp as possible, but that didn't work very well. I then switched to using a vise:

That worked much better. After a bit, I had something like this:

It took some effort, but I had it completed in about a half an hour. Now, I needed something to attach it to. I took the bit of 3/4" copper piping I got for free from a local hardware store and soldered it to my copper reflector plate. I also used a dremel tool to remove a few millimetres from one edge, so that the antenna would not touch it when it came up from the pipe. The result looked like this. Note the excess solder. I don't do this sort of thing often enough.

I then soldered a center post to the n-connector (which protruded through the center of the pipe), and tried to solder it to the finished double biquad. What a serious pain that turned out to be. After some thought, it occurred to me that I probably should have made the center post of the biquad part of the double biquad itself -- i.e., why snip it off when I could have simply bent it 90 degrees straight down. Also, I snipped the two ends that should have been soldered to the pipe a bit short, and soldering them to the copper piping turned out to be rather problematic.

I plan on trying this again. This time, I'll make the center post and the double biquad out of a single piece of copper, and leave the two "tails" that have to be connected to the pipe a bit longer than they need to be. I'll use the dremel to create two small grooves in the top of the pipe, lay the two tail ends in those grooves, and put a drop of solder on each. That should make things simpler.