So I recently decided that I to build a new antenna for my 70 cm rig to replace the dual band magnet mount that I was using as it did not fit well in my new shack. I ended up building what I like to call the 70 cm crucifix. It’s nothing really new or exciting as far as design goes. It is based it off of this by PA1CA. However, I did modify the design a bit.
It’s a full wave quad so the wire is 70 cm long and each side of the square is about 17.5 cm in length. I used two ring connectors to make terminals that I could solder my coax to. Measure from corner to corner of the square is about 25 cm.
Rather than using PVC pipe, like in the original design, I used a 1/4″ wooden dowel and left the bottom longer as I had anticipated mounting it at the peak of the roof of my shack (thus creating the crucifix look). I used plain old wire ties to hold it all together. The wire I used is 14 AWG electrical wire that I stripped the jacket off of. You should be able to use just about anything that you have laying around though.
If you want to change the polarity of the antenna you should be able to feed it from the bottom rather than the side, where I did.
Keep in mind that this type of antenna is directional. In this case, it would be bidirectional since it does not have a reflector on the back side. This is fine for me since I am using it with my old Motorola Phoenix SX rig which only has two channels that are programmed for a couple of local repeaters that I use. This is also the reason why I can get away with using RG-58 coax for a feed line.
Edit: The SWR on this floats between 1.0:1 and 1.5:1 however it is resonant at 447.28Mhz which is right around where I use it.
Sorry about the photo quality.
73 for now!