+
EQUATIONS USED
+
Notes:
+ The Magloop Antenna Calculator was developed to predict the characteristics of a small-loop (aka "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
+
+ 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:
+
+ - ⌀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.
+ - 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.
+
+
Calculated parameters:
+
+ - L : Inductance in microhenries.
+ - 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.
+
+
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.
+
+
References:
+ [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.
+
+
Change history:
+
[28-Sep-21]
+ * Commenced development.
+
+
+