FlightAware Discussions

Spider Antenna Construction Questions

When making an Spider antenna, does the base where the 68mm legs are attached to have to be metallic/magnetic?

Or can I use an Aluminum base that has a 68mm wire going doing at a 45º angle?

Is there a size to the square base that it needs to be no larger than?

Example 5" X 5" Square with a hole in the center for the coaxial wire to attach to and the parameter has the 68mm wires or should this be smaller in diameter?

I would assume @abcd567 can give some advice. He’s the FA master of science in DIY antenna creation

Metallic, yes.
Magnetic, not neccessary.

Aluminum is metallic, so is ok.

The flange of SO239 connector is 1" x 1" , and proved ok by actual use.

A large base like 5" x 5" will provide a very large horizontal ground plane, and mask the SWR improvement by slanting radials. Do not use such a large horizontal base.

If instead of SO239 connector, you want to use a metallic plate, with a hole in center for passing whip, and 68 mm 45° slanting wires attachad to its perimeter, then do not use more than 1" x 1" rectangular plate, or 1" dia circular plate/washer.

Thanks, the first spider I made was made out of a tin pan lid and it was roughly 3" square. Worked good but it rusted out in the elements so I wanted to make one out of Aluminum.

I will decrease the parameter dimensions. The Type N connector body us 5/8" in diameter so a 1" square would be hard to make as there’s little surrounding wall area