7 turn Helical FPV antenna (5.8 GHz)

myminifactory

I designed a 7 turn helical antenna that has gained significant popularity since its creation several months ago. The original design can be found here: http://www.thingiverse.com/thing:858112. I received numerous requests for a longer version, which prompted me to create this new one from scratch. Unlike the previous antenna, which was a remix of another design, this one is entirely my own work. I've often wondered why helical antennas have a base reflector that's exactly one wavelength in diameter. Would increasing the size of the base make a difference? In the past, I discovered Serbian university research papers detailing practical tests on different reflector designs for helical antennas. These studies revealed that a bowl-shaped reflector with a 2.5 wavelength diameter significantly outperforms the standard 1 wavelength disc. I've created such a reflector design. If you decide to use it, you can attach aluminum or copper foil to its surface or utilize it as a template for a reflector in copper or brass mesh. Additional research suggests using a cylindrical reflector, which appears promising due to its ease of realization in various materials. However, I haven't designed anything yet: http://home.etf.rs/~milanilic/publications/papers/AWPL-2006_01624449.pdfhttp://home.etf.rs/~milanilic/publications/papers/Olcan-Eucap06.pdf The design criteria for this 7 turn antenna are identical to those of the 5-turn version: I aimed to create an antenna that provides full protection for the wire, is compact and easy to print, and doesn't require glue for assembly. My design consists of two parts held together with a single screw – it can't get any simpler. Both left and right-hand polarized versions of the former and the wire holder are available. Be sure to print the version you need. Build Instructions The reflectors should be seen mainly as templates. Print one and use it to produce a reflector out of PCB material or copper. If using a PCB, ensure the copper surface faces forward – i.e., the side where the wire holder is attached. Insert the antenna connector into the outermost hole of the reflector and trim the wire 5-6 mm above the surface. Fan out the outer isolation of the antenna wire and solder it to the reflector. There's a picture illustrating this step for clarity. Apply paint or lacquer to the reflector to make it fingerprint-proof, although this is purely aesthetic and can be skipped. Print the holder and former separately. Use the wire former to create a spiral shape from the wire. Thread the wire onto the holder and trim it to length while in place. Fasten the holder to the reflector using an M3 screw and nut. The final step involves soldering the main wire and antenna center wire together. To achieve optimal results, ensure the connection to the antenna wire is precise. The main wire should run parallel to the reflector board for its last 4 mm of length, located 2 mm from the surface of the reflector (thanks to Dave855 for this information). Designing This I created this design in FreeCAD, a competent and free although somewhat challenging to master 3D design program.