Good Luck with “Wire Collinears”.
After making about one dozen FAILED “Coaxial Collinear” (Coco) antennas, I decided to make “Wire Collinear” (vertical wire sections with interposing stubs and/or coils). I tried over a dozen designs, and all performed much less than a 1/4 wavelength ground plane (Spider/Cantenna).
Here is a photo of some of these Wire Collinears, which I found in my scrap parts drawers. There were many more, but have been digested by trash bin. The top 7 are only whip part, which were soldered to a SO239 connector with radials. The next two are variants of J-Pole, and last 2 at bottom are Zeppelin, the original antenna used in German Zeppelin air ship (1895), and Slim Jim was derived from it.
Zeppelin Antenna Hanging from a Balloon
German Patent Number: 225204
Inventor: Hans Beggerow
Original Document: German Patent Number 225204
Claim (translated from the original German): Airborne wiring diagram, marked by two dangling wires of unequal length, which in the vicinity of the airship form a Lecher system.
J-Pole and Variants