This is an upgrade version of my former 8 turns helical antenna
For this antenna I used a 10x10mm Aluminium tube. The helical mounting arms are a print part.
Antenna mount is the same as with the 8 turns version.
Update August 2018:
- I made a new antenna mount to be able to mount the helix on a photo tripod.
The new fixture part will accept a 1/4" nut for photo tripods.
- For matching the antenna, I made a simple clamp to bring the first 1/4 turn of the helix
1,8mm parallel to the reflector.
- I tested the antenna with an antenna analysator at the working frequency for Inmarsat C
EGC channel - the VSWR is 1:1.255@1541,500, the lowest VSWR is 1:1.161@1546 MHz.
The new parts are available here.
More about this project can be found on my blog:
Print 23 helical mounts.
Print one boom mount and one boom end cap.
Print one antenna mount
Use 10x10mm Aluminium tube
Use M3 nuts and bolts for mounting helical mounts to boom and mount matching clamps to reflector.
Use 0,8mm Aluminium sheet metal for 140mm Dia. reflector.
Use 2,7mm Dia Copper wire (without shielding).
Use one 1/4" nut for antenna mount for camera tripod.