Posts filed under ‘Construction’

Constructing My First Double Cone Antenna

After trying to make a cone from the end of a long length of cable, as discussed here, I decided to use two precut lengths of cable (no idea what lengths I should use), make two cone-shaped coils, and then join them together afterwards.

Building the Second Coil

I cut two roughly 6 ft. lengths of bare 8 gauge copper wire.

Instead of starting freehand, I found something hard and cylindrical since I don’t have a cone handy yet (a large glass bottle with a small neck worked) and wrapped each coil around the base of the glass bottle near the bottom and the neck of the glass bottle near the top, giving me a round starting point to work with.

I then started adjusting the cylindrical coil by extending its length and shrinking the size of the coils at the top, or widening it near the bottom. After finding an online protractor tool and using several sheets of paper taped together to draw out a large 33 degree cone, I shaped the cone to the dimensions needed just by laying it down on the table and eyeballing it.

Measuring and Shaping a 33 Degree Cone

Measuring and Shaping a 33 Degree Cone

Cylindrical and Cone-shaped Coils

1 Cylindrical Coil, 1 Cone-shaped Coil

Pair of Cones

Pair of Cones

You can see that they’re not perfect. When you shape it properly from one direction, it’s not really all that good looking from the side. This is why first fashioning a cone-shaped template to wrap the wire around would really help.

For now though, it’s okay. We’re just getting something built so that we have something to experiment with.

After getting the two cones made and looking somewhat similar, it was simply a matter of inverting one, bending the tips so that they pointed towards each other, and then sliding each tip into the aluminum connectors.

I made sure the copper tips connected inside the connector so that I don’t rely on the current passing through aluminum. I dunno if it requires one single type of metal, but as long as the copper is connected throughout, that should be one less variable.

Completed Bare Antenna

Completed Bare Antenna

I got everything built and adjusted so that each of the cones passes through the other vertically. You have to tweak the ends or else it may lean off to one side.

If you look at this antenna, you’ll see that the point of the coil points towards the end and stops. It’s the larger base that bends back in and connects to the tip. This is a great idea because then it doesn’t matter what direction it comes in from. I had the tip of the cone go out, and it was a little more challenging to deal with the smaller loop at the top and turning it whichever way it needed to go to get back outside and reconnect there.

You’ll notice that I have a section near the middle that’s been wrapped in electrical tape. The two cones are coming in contact with one another there and so I taped it off to prevent the bare copper wires from touching somewhere they shouldn’t be. This won’t be a problem with insulated wire, fortunately.

So there ya have it. Completed antenna. Time to start running some power through it and see what happens! 😀

Oh, for future reference in subsequent antennas, in this video Bashar points out that some of the variables that we can tweak include the quality of our materials, the number of windings, the size of the cone, and so on.

August 7, 2009 at 8:53 am Leave a comment

Attempting My First Antenna

So I went to Home Depot and bought a number of items:

  • A length of bare 8 gauge copper wire ($0.48/ft)
  • A length of insulated 12 gauge copper wire ($0.25/ft)
  • Some metallic connectors to connect two ends of the bare wire
  • Some “butt splices” which are basically connectors for the smaller 12 gauge wire
  • Some wire cutters/crimpers/strippers

Wire Choices

The reason I went with those two wires is because I wanted to deal with wire rather than a tube for ease of use to bend it by hand. I also needed something stiff enough to maintain its shape once its been shaped the way I want.

You can go larger than 8 gauge bare copper wire, and the 6 gauge is definitely stiffer than the 8 gauge I got. I may consider getting some if the 8 gauge doesn’t hold well enough. That said, Bashar talked about using insulated wire so I’ll probably be going that route first anyways.

You can go fatter than 12 gauge insulated copper wire, but you had to switch to a whole bunch of smaller copper wires bunched together in a larger insulated container. I found this to be much more flexible than a single piece of copper. It doesn’t maintain its shape nearly as well as a single piece. That said, the 12 gauge insulated wire seems to hold its shape pretty well.

Building the first antenna

For the first antenna I took the long length of bare 8 gauge copper wire and started coiling one end of it freehand.

First Single CoilThis seemed to work alright at first. It wasn’t pretty, but it was starting to make the coil shape. There were a few main problems I ran into using one long length of cable like this:

  • The coil was made of a bunch of little angled bends rather than a smooth circular shape. Not sure how much this’ll matter in the end.
  • When it was time to start making the second coil back down, it was tough to make the turns with the heavyish coil already hanging down, plus the loooong length of cable I was working with on the other end. It was getting a little cumbersome.

Seeing this, I gave up on this coil and decided to start anew, using two precut lengths of copper cable and joining them together in the end.

August 7, 2009 at 8:38 am Leave a comment

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