Opticoil 2.3 is the web-based version of a tool for designing and optimising single-layer helical inductors with round wire in the MF- to VHF range, in particular for high-power applications such as loading-, filter- and ATU coils. A design can be made from L/D = 0 (single loop for e.g. magnetic antenna) to almost a straight wire.

It builds on the work of Maxwell, Lorentz, Rosa, Nagaoka, Medhurst and many others. With the advent of the microcomputer Dr. David Knight, Robert Weaver, Alan Payne and many others have made substantial refinements to existing theory.

This tool uses existing theory and publicly available formulas. It reverses the usual calculations "dimensions to self-induction" using a solver that will find a series of possible solutions for a given self-induction or reactance. Thermal calculations are added, based on power dissipation and heat flux.

The results are presented for a wide range of L/D values. In this way, you can adjust your design to available space and temperature / ventilation requirements. Moreover, it gives a one-glance overview of what is possible.

Q=X/RAC. Calculation of RAC is sum of Runwound + Raxial + Rradial according G3RBJ. For comparison, the Q is also calculated from interpolated values from Medhurst's table.

Yellow boxes = input, blue boxes = output.

Typical usage:

1) Design a network with Elsie or LT Spice, and minimise insertion loss. Highest Q = XL/RL for the inductors (and also for the capacitors) gives minimum losses.

2) Use this tool to find number of turns, wire thickness, diameter and length for a given inductance and current load. Result is a design for optimum Q and lowest heat generation due to Ohmic losses.

3) Note that for power applications (>100W or so), capacitors with a dielectric loss of < 0.1% and sufficient current capability (usually silver-mica) are required. Typical disc ('knob') C's have high losses and will get hot at high currents!

No responsibility whatsoever for using this program is assumed. Use at your own risk and peril.

Enjoy, PA2EVR 2016-