Magnetic Loop Antenna Calculator

A magnetic loop antenna is a compact and efficient design used in radio frequency (RF) communication and reception. It is characterized by a loop of wire that forms a closed circuit, often shaped like a circle or square. The key feature of a magnetic loop antenna is its ability to generate a strong magnetic field within the loop when an RF current flows through it.

The loop's size is typically a fraction of the wavelength of the radio waves it is designed to transmit or receive. This allows magnetic loop antennas to be relatively small compared to other types of antennas, making them suitable for constrained spaces or portable applications. The loop's electrical characteristics, such as its inductance and capacitance, are carefully tuned to resonate at a specific frequency or within a narrow bandwidth.

Main loop diameter in cm
Loop conductor diameter in mm
Tx Power in Watt
Frequency in kHz
Choose between the Metric and Imperial systems of measurement.
Choose a material.
⌀ 120 cm
⌀ 120 cm
⌀ 25.4 mm
⌀ 25.4 mm
Main Loop
Main Loop
Coupling
Loop
Coupling...

Overview

BandFrequency (MHz)Efficiency (%)Quality FactorCapacity (pF)vCap (kV)Bandwidth (kHz)perimeter⁄λ
160m1.8000.32 2075 2592.0 0.8 0.9 0.02 < 1⁄8λ
2.0000.46 2184 2097.6 0.9 0.9 0.03 < 1⁄8λ
80m3.5003.15 2811 678.1 1.4 1.2 0.04 < 1⁄8λ
4.0004.94 2950 516.8 1.5 1.4 0.05 < 1⁄8λ
60m5.35112.57 3138 284.3 1.8 1.7 0.07 < 1⁄8λ
5.36712.68 3138 282.6 1.8 1.7 0.07 < 1⁄8λ
40m7.00026.91 3000 161.9 2.0 2.3 0.09 < 1⁄8λ
7.30029.89 2939 148.1 2.0 2.5 0.09 < 1⁄8λ
30m10.10057.05 2118 72.5 2.0 4.8 1⁄8λ ≤ 0.13 ≤ 1⁄4λ
10.15057.47 2102 71.7 2.0 4.8 1⁄8λ ≤ 0.13 ≤ 1⁄4λ
20m14.00080.64 1124 32.9 1.7 12.5 1⁄8λ ≤ 0.18 ≤ 1⁄4λ
14.35081.95 1061 30.8 1.7 13.5 1⁄8λ ≤ 0.18 ≤ 1⁄4λ
17m18.06891.05 590 15.7 1.4 30.6 1⁄8λ ≤ 0.23 ≤ 1⁄4λ
18.16891.20 582 15.4 1.4 31.2 1⁄8λ ≤ 0.23 ≤ 1⁄4λ
15m21.00094.51 390 9.0 1.2 53.8 0.26 > 1⁄4λ
21.45094.88 368 8.2 1.2 58.3 0.27 > 1⁄4λ
12m24.89096.90 240 3.5 1.1 103.6 0.31 > 1⁄4λ
24.99096.94 238 3.4 1.1 105.2 0.31 > 1⁄4λ
11m26.96097.63 191 1.5 1.0 141.5 0.34 > 1⁄4λ
27.41097.76 182 1.1 1.0 151.0 0.34 > 1⁄4λ

By Frequency

Main loop perimeter
3.77 m
Perimeter/Wavelength
0.176 λ
Coupling loop (20% of main loop)
0.75 m
Bandwidth
12 kHz
Tuning Capacitor
33 pF
Capacitor Peak Voltage
1.7 kV
Efficiency
80.6 %
Inductance
3.00 μH
Quality factor
1124
Radiation resistance
189.62 mΩ
Conductor resistance
45.52 mΩ
Loop Area
1.13 m²
For Small Transmitting Loop antennas (STL) to be considered truly magnetic, their circumference should fall within the range of 1⁄8 to 1⁄4 of a wavelength. Within this range, a uniform current distribution across the loop is achieved.
The optimal length of the outer conductor is typically fixed at 1⁄4 wavelength for the highest frequency of interest, maximizing efficiency. Conditions remain acceptable as long as the transmission wavelength does not exceed 1⁄8 wavelength.
If the loop length surpasses 1⁄4 wavelength, it ceases to function effectively as a "magnetic" antenna. Conversely, if the loop length is less than 1⁄8 wavelength, efficiency is dramatically compromised