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:

- circular, octagonal, hexagonal and square-shaped loops
- main loops made from either hollow round anodised-copper or aluminium conductors
- metric and imperial units
- magloops with 1-to-8 turns

-- 73 de VK3CPU

- ⌀a : Conductor diameter in millimeters (mm) or inches ("). (Measured between opposing conductor outer surfaces.)
- ⌀b : Loop diameter in meters (m) or feet ('). (Measured between the conductor centers.)
- N : Number of turns or loops. Sweeping left-to-right for parallel multiloop, then single loop, then series multiloop configurations. A "(P)" indicates a multiloop antenna configured with parallel main loops.
- c/a : is the spacing ratio; based on 'c' being the inter-winding spacing for multi-turn loops measured between conductor centers, and 'a' is the conductor diameter. (Must be >= 1.1) A low-value will increase the resistance due to the proximity effect. (Ignore for single-turn loops.)
- Tx : The transmit power in Watts. This affects the predicted voltage across the capacitor (Vcap), and the RMS loop current (Ia).
- Re : Additional resistance due to external losses, due mainly from capacitor contact resistance and proximity-to-ground effects. Use Re=0.0 to assume the loop is in free-space with no capacitor losses (i.e. ideal conditions, with loop-related losses only). Adding Re will reduce antenna efficiency, Q, Vcap and Ia, while increasing antenna BW. According to [1] and [2], a 1 m diameter loop of 22 mm copper tubing at a height of 1.5 m above the ground operating at 7 MHz had a calculated capacitor contact resistance of ~190 mΩ and an additional ground proximity loss resistance of ~30 mΩ. Note that true ground losses are dependent on both frequency and height-above-ground.
- Metric or Imperial : selects the measuring system.
- Cu or Al : selects the type of metal conductor (annealed copper or aluminum).
- Circ, Oct, Hex or Sqr : selects the shape of the magloop.

- L : Inductance in microhenries. Equations from [3].
- A : Loop area in square meters or square feet.
- C : Effective capacitance of the loop in picofarads.
- peri : Perimeter of the main loop in meters or feet.
- c : Distance between windings, measured from the conductor centers in mm or inches.
- cond : Total required conductor length in meters or feet.
- Tuning Cap (pF): The capacitance required to bring the loop into resonance at the given frequency. Value in picofarads.
- Vcap (kV): The predicted voltage across the capacitance given the desired transmit power.
- BW (kHz): The predicted 3dB bandwidth of the magloop antenna.
- Efficiency (%): The percentage of input energy that is actually radiated and not lost as heat.
- R-radiation (Ω): The calculated radiation resistance of the loop in ohms.
- R-loop (Ω): The calculated resistance of the loop in ohms, due to the combination of material conductance, conductor length, skin-effect and proximity effects.
- Reactance (jΩ): The inductive reactance of the loop in ohms.
- Q : The antenna Q (quality) factor.
- Ia (A): The RMS loop current in amps.
- Perimeter (λ): Antenna perimeter size relative to the wavelength.
- Skin depth (μm): Conductor skin depth in micrometers.

[1]: B. Austin, A. Boswell and M. Perks,

[2]: A. Boswell, A. J. Tyler and A. White,

[3]: F W Grover,

* Added support for URL parameters. Some code-base clean-up.

* Changed radiation and loss resistance to logarithmic. Capacitance limited to 5-5000pF.

* Stopped autoscaling on all axes. Changed Vcap, Icap to logarithmic. This makes it easier when comparing different configurations.

* Added conductor skin depth as a new calculated parameter.

* Changed the frequency list to include VHF (2m) and UHF (70cm) bands.

* Reduced minimum loop diameter to 4 cm.

* 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.

* Added support for parallel conductor magloop antennas.

* 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

* 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.