Miguel VK3CPU - Magloop Antenna Calculator V10.4
2D Chart Canvas


The Magloop Antenna Calculator was developed to predict the characteristics of a small-transmitting-loop (aka "STL", "magnetic loop" or "magloop") antenna, given physical dimensions entered via slider widgets.
It supports: I developed this multi-turn capable magloop calculator to take advantage of the touch-screens and high-speed of modern mobile phones, to allow users to get realtime feedback of the predicted behaviour of a magloop antenna.
-- 73 de VK3CPU

Inputs via the slider and radio widgets: Calculated parameters: Usage hints:
  • Tap on legend items to disable or enable an output parameter. This can be used to declutter the chart.
  • Tap on a chart 'dot' to display a tooltip containing calculated output parameters for that frequency or band.

  • Other VK3CPU calculators:
    [1]: B. Austin, A. Boswell and M. Perks, "Loss Mechanisms in the Electrically Small Loop Antenna" , IEEE Antennas and Propagation Magazine, 56, 4, August 2014, pp. 143.
    [2]: A. Boswell, A. J. Tyler and A. White, "Performance of a Small Loop Antenna in the 3 - 10 MHz Band" , IEEE Antennas and Propagation Magazine, 47, 2, April 2005, pp. 5 1 -56.
    [3]: F W Grover, "Formulas and Tables for the Calculation of the Inductance of Coils of Polygonal Form" Scientific Papers of the Bureau of Standards, Vol 18, p753

    Change history:
    [21-Dec-23] - V10.4
    * Added CB frequencies (11m, 26.965 - 27.855 MHz).
    [26-Aug-23] - V10.3
    * Added support for URL parameters. Some code-base clean-up.
    [13-May-23] - V10.2
    * Changed radiation and loss resistance to logarithmic. Capacitance limited to 5-5000pF.
    [8-May-23] - V10.1
    * Stopped autoscaling on all axes. Changed Vcap, Icap to logarithmic. This makes it easier when comparing different configurations.
    [8-May-23] - V10
    * Added conductor skin depth as a new calculated parameter.
    [23-Apr-23] - V9
    * Changed the frequency list to include VHF (2m) and UHF (70cm) bands.
    * Reduced minimum loop diameter to 4 cm.
    [12-Feb-22] - V8
    * Changed the frequency list to include top and bottom frequencies of each band. This is to highlight the range of capacitance required between the top and bottom of each band.
    * Increased max c/a ratio from 10 to 30.
    [13-Jan-22] - V8
    * Added support for parallel conductor magloop antennas.
    [21-Nov-21] - V7
    * Upgrade Chart.js to the latest version, v3.5.1.
    * Tooltips are now justified, (using monospace fonts) and support changing metric prefix.
    * Added band wavelength to tooltip display. Changed 60 m band from 5.0 to 5.3 MHz..
    * Added metal type to schematic display.
    * Reduced display precision for Cap and Q in tooltip.
    * Changed Tuning Cap scale max from 2000 to 1000 pF.
    * Changed Q equation back to the original Xl/Rtot. Changed max Q to 4000.
    * Introduced a new slider "Re" to inject external losses to account for the combined losses due to capacitor contact resistance and ground losses.
    * Renamed R-loss to R-loop to avoid confusion, as loop resistance is no longer the only resistance that contributes to losses. The other being Re.
    * Changed to V6 to capture the significant changes.
    * Added antenna perimeter size in wavelength to the chart display as a new item.
    * Changed maximum spacing ratio c/a from 4.0 to 10.0. Values higher than 4 have no further effect on proximity resistance, but does reduce coil inductance which drives up the SRF.
    * Added distributed capacitance calculation and display for the single turn loop.
    * Increased supported conductor diameter to 80 mm. (3.15 inches)
    * Updated to V5; Added support for octagon, hexagon and square shaped loops. Moved and hyperlinked equations-used to a separate page for clarity.
    * Updated to V4; Updated equation used for Q to match the one use in the ARRL Antenna Book. This will affect predictions for V_cap, I_loop and BW. (Based on Q equation D.1 used in "Impedance, Bandwidth, and Q of Antennas" by A D Yaghjian, IEEE Transactions on Antennas and Propagation, April 2005.)
    * Added equation graphics for V_cap, I_loop and BW formulas.
    * Flipped the main-loop graphic to have the capacitor above the coupling loop.
    * Set maximum values to Q, Vcap and I axes to stop autoscaling. Max Q set to 2000, Vcap to 20 kV and I to 100 A.
    * Added formula/equation graphics in Notes section. A few more complex ones, such as effective capacitance and SRF, are still needed.
    * Fixed minor error in calculation of resistive loss due to proximity effect.
    * Added visual cues for all slider-controlled parameters to highlight which parameter is being modified in the graphic representation.
    * Added c/a display to graphic representation. Moved N from center to left.
    * Added SRF calculation and display for multi-loop antennas.
    * Added support for imperial units and for aluminum metal.
    * Added total conductor length display.
    * Added loop circumference display.