Lamprey - Vertical Antenna w/Parametric Loading Coil

I wanted to make a ‘multi-band’ vertical for POTA activations and motorcycle camping that didn't require a tuner. I use a 25' telescoping pole and this is designed to lash to the base with a bungee.  I did not mind changing loading coils to achieve different bands. It basically allows me to use any nonconductive pole to support the radiator.

One end of the radiator is attached to the top of the telescoping pole, and the other attaches to the top of the coil with an alligator clips. A chassis mount SO-239 uses a small jumper with an alligator clip to connect to the base of the coil and the radials connect to the screws that mount the SO-239 connector to the bottom (pictures soon)

Instructions:

Visit Loaded Quarter Wave Antenna Inductance Calculator – M0UKD – Amateur Radio Blog to calculate the needed inductance based on the length of your radiator and desired frequency.

Visit https://www.translatorscafe.com/unit-converter/en-US/calculator/coil-inductance/ to calculate the number of turns and length required based on a 50mm coil. For example, for a 50mm form, 1 uH is pretty close to 4 turns at 18mm long. Use whole turns and a minimum length of 3mm times the number of turns. I start with 4mm per turn.

Once you have a coil that matches the inductance you need, enter the length and number of turns into the Fusion 360 drawing parameters. The 3D model will adjust itself accordingly. You will still need to trim the antenna with an SWR meter or antenna analyzer, but this should get you pretty close.

It's all very trial and error still, but hopefully it will generate feedback to make a better tool. It sure makes nice coils!

73!