Nation Institute for Nuclear and High Energy Physics

AIRCOIL
Design of self-inductance ,
by Pieter J.T.Bruinsma, PA0PHB

 
Pieter J.T. Bruinsma, PA0PHB
Pieter J.T.Bruinsma
   Engineering notes   

Aircoils are used in electrical and electronic circuits by professionals and radio amateurs.
Design parameters for multi-turn aircoils can be obtained if inductance and operating frequecy are known. The actual selfinductance of the constructed multi-turn aircoil will not deviate more than a few percent of the design value. The selfinductance can be varied by +/- 10% by adjusting the length of the coil.

This program makes use of the design methods used in the Radio Engineers' Handbook by Frederick E. Terman.

Instructions

Follow the steps in the scheme below.
Enter inductance and (highest) operating frequency.
The program will return with a suggestion for diameter and length of the coil as well as wire thickness and number of turns. The capacitance value, with which the coil will resonate at the given frequency, is given to assist you in the design of resonant circuits.
You can adjust the dimensions of the coil, to comply with requirements byond the scope of this program, and observe the effect on the Q (the quality-factor).
Fine tuning of the wire thickness is the last step.

Summaries of the resulting parameters are presented simultaneously in the result window.
A complete report of the outcome of the design steps of the websession can be obtained by pressing 'Show all results'.

Design criteria

  1. The design is based on a single layer, multiturn coil configuration.
  2. The wire thickness is adjusted to half the turn-to-turn spacing.
  3. Global frequency range: 1 kHz - 1 GHz . A warning will be given, when the wire length exceeds 1/10 of the wavelength.
  4. When used as inductor in resonance circuits, the resonanting capacitance should be larger then a few picofarads. Large inductance at high frequencies may call for low parasitic capacitance.
  5. If the coil is to be shielded, a correction for the self-indeuctance should be be made. If the inner diameter of the - metallic - shield is more then twice the coil diameter, the correction factor is less then 10%.
  6. The Q - quality factor of the coil - strongly depends on the quality of the insulating materials of the coil support.
    The calculated value do take skin effect and proximity effect into account.

Calculations

Design of single layer multi turn coils

Step 1
Enter
Self-inductance (microH) Frequency (MHz)
This coil will resonate at the given frequency with picofarad
Step 2
Modify coil
Diameter (mm) Length (mm)

Number of turns is


Results, comments

 
Step 3
Modify by +/- 30% and [ENTER]

Modify
Wire thickness (mm)
Calculated

Quality factor becomes
Length of wire (mm)
DC resistance ohm
AC resistance ohm
Effect. shunt resistance ohm

Not satisfied => Repeat step 2

 

Nederlands

Other configurations

Wire loops
Straight wire
 
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Last modified 2018/07/06