Building a 6m "Squalo" Antenna

21 January 2022

I was browsing the Internet for radio antenna ideas and I stumbled across PA3EGH's site with quite a few copper ham radio antenna projects. I saw several pics of the squalo antenna for 2 and 6 meters. I recently moved my 2m/70cm open-stub j-pole to the peak of my house with some new lmr400 to it. I am quite happy with it’s performance, so I thought a 6m project would be a lot of fun. I finally have a transceiver (FT-991A) that will do 6m, and I have yet to check it out. So I decided I would give the 6m copper squalo anteanna a go!

6m squalo mounted on roof
6m squalo mounted on gable

Theory

The squalo antenna is a 1/2 wave dipole that is similar to a halo antenna, but instead of being bent into a circle, the squalo is shaped into a square. The dipole is bent around and creates the perimeter of the antenna. The far ends (across from the feed point) do not touch. To provide rigidity, a small piece of CPVC pipe and two collars are inserted in the gap, connecting each side together. Depending on how close the copper pipe ends are separated from one another, a capacitance can be formed that can change the resonant frequency of the antenna. When mounted parallel to the ground, the squalo is mostly an omnidirectional radiating antenna with a horizontal polarization.

Materials

The plans call out for ½” copper pipe, 8 elbows, and some 1/4” CPVC connectors and a short length of CPVC pipe.

6m squalo plans
6m squalo plans from PA3EGH

Construction

I started with the two outer elbows connected together with the CPVC pieces. I soldered most of the elbows on the concrete ground with small blocks of wood to elevate the copper pipe pieces. I was carfeul to try and keep the antenna square, keep the antenna in the same horizontal plane.

Dry fitting the perimeter
Finding the center of mass

I essentially split the antenna into two identical mirrored pieces when game planning during the construction phase. For each piece, I measured, cut, prepped, and soldered the copper pieces together. Once both identical sides were made, I used the ½” CPVC pieces to fill the “gap” between the two pieces. For the middle piece, the length of the arms is used to balance the antenna. I used a piece of aluminum rod and a square to roughly find the center of mass of the antenna. I found it roughly close to the middle, as one would expect. I made the “end cap” with two elbows and a short piece of copper pipe. I added the cap to the copper pipe arms before soldering them together. I used the aluminum rod again and then cut the arms to balance the antenna where I thought my aluminum antenna bracket would go, approximately 1-3/4” from the inside of the cap.

Checking center of mass
Using vice to make it flat

I then finished soldering the entire antenna together. The antenna was fairly square, but it was just a touch off. I used a bench vice and also a clamp to hold the antenna in square. I then re-heated up the elbows and watched the antenna snap flat. I added a bit of solder back to the connections to keep them solid. I didn’t want to re-heat the connections too much as to not overheat them or compromise their integrity.

Once the antenna was mostly soldered together, it was time to create the antenna mount out of aluminum angle. Once cut to length, I used a drill press to drill the holes for the u-bolts for the antenna arms and the antenna mast.

Tuning

I used a ladder to hold up a temporary antenna mast in order to elevate the antenna to minimize ground losses.


Thank you for reading thus far. This write-up is currently under active construction and I hope to have it completely up shortly. Please check back again later. Please send all comments or suggestions to tanner.j.sterling@gmail.com