antennas:qfh
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antennas:qfh [2024/04/16 20:11] – created m0lte | antennas:qfh [2024/04/24 19:15] (current) – 2m0vsr | ||
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From Scott - 2M0VSR: | From Scott - 2M0VSR: | ||
- | https:// | ||
- | Quadrifilar helicoidal antenna - Javascript on-line calculator | + | **Credits** |
- | Compared to solid core wire, it's quite easy to get it into shape, or close enough that it tunes almost smack centre in the band | + | Inspired by this build: https:// |
- | I think the rods are M5 or 6 threaded rods | + | **Summary Instructions** |
- | Whole thing can be built for less than £20 | + | The above link has a better guide but the TLDR version is: |
- | Think it was this that gave me the original idea: https://tf1ez.com/ | + | * Generate and print the paper templates based on the type of PVC pipe you have. Use: https://jcoppens.com/ant/qfh/ |
+ | * Tape the cut-outs onto the PVC pipe, making due they are aligned down the pipe. | ||
+ | * Drill out the holes. The centre ones are not strictly needed but you may find it useful to use some wooden dowel rods to support the banding. | ||
+ | * Cut the threaded rods down to size based on the calculator. Leaving them a little long won't do any harm. | ||
+ | * Put the threaded rods though and use a washer/nut against the PVC pipe to hold in place. | ||
+ | * Cut the Banding so that it stretches to the opposite bottom rod. I'd leave a bit extra and trim. | ||
+ | * Use 2 nuts/ | ||
+ | * Attach the Coax ends to the top of the antenna | ||
+ | |||
+ | |||
+ | **Notes: | ||
+ | |||
+ | * You can use low gauge wire as an alternative to banding but it's much more difficult to work with and get aligned well. I used 10mm earth wire for an earlier | ||
+ | |||
+ | |||
+ | **Parts List** | ||
+ | * - PVC Pipe (55mm, 1meter or similar) | ||
+ | * - Galvanised Steel Banding - [[https:// | ||
+ | * - M4 Threaded Rods (x4) [[https:// | ||
+ | * - M4 Nuts (x24) [[https:// | ||
+ | * - M4 Washers (x24) [[https:// | ||
+ | * - Good Quality Coax. (Messi Hyperflex 5 / Ultraflex 7) [[https:// | ||
+ | |||
+ | Whole thing can be built for less than ~£25. Less if you shop around / scavenge a bit more. |
antennas/qfh.txt · Last modified: 2024/04/24 19:15 by 2m0vsr