The Magloop Antenna Calculator was developed to predict the characteritics of a small-loop (aka "magloop")
antenna, given physical dimensions entered via slider widgets. There are many magloop calculators available
online. Some require installing a program on your computer, which is OS dependent. Some others are browser-based,
but require parameters to be input using a keyboard. I wanted to create a tool that took 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. This would help a radio amateur to decide on the characteristics for the build.
Inputs via the slider widgets:
- ⌀a : Conductor diameter in millimeters (mm). Estimated equivalent AWG wire size is also displayed where appropriate.
- ⌀b : Loop diameter in meters (m).
- N : Number of turns or loops.
- c/a : 'c' is the inter-winding spacing, and 'a' is the conductor diameter, so 'c/a' is the spacing ratio. (Must be >= 1.1)
A low-value will increase the resistance due to the proximity effect.
- Tx : The transmit power. This affects the predicted voltage across the capacitor.
- L : Inductance is calculated using Nagaoka's equation. Value in microhenries.
- A : Loop area in square meters.
- C : Capacitance for multi-turn loops, which is calculated using Knight's 2016 paper on self-resonance and self-capacitance of solenoid coils.
- c : Distance between windings, measured from the conductor centers (mm).
- 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. This is calculated from the predicted Q and the center frequency.
- Efficiency (%): Calculated from the radiation resistance divided by the sum of radiation resistance and the loss resistance.
- R-radiation (): The calculated radiation resistance of the loop in ohms.
- R-loss (Ω): The calculated loss resistance of the loop in ohms, due to the combination of conductance, skin-effect and proximity effects.
- Reactance (jΩ): The inductive reactance of the loop in ohms.
- Q : The quality factor, which is the reactance divided by the resistance of the loop at that frequency.
- Ia (A): The RMS loop current in amps.