Magnetic Loop Antenna Calculator   •   66pacific.com

Small transmitting loop antennas, commonly called "magnetic loops" or "mag loops," can give surprisingly good performance when they are carefully designed and constructed. This calculator enables you to test the design of an octagonal loop antenna and to answer "what if" questions until you arrive at a design that meets your needs.

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Length of Conductor (antenna "circumference")
feet
 
Diameter of Conductor
(For efficiency, should be > 3/8" or 1 cm)
inches
 
Frequency
 megahertz
 
Transmitter Power (optional)
 Watts

Units of Measurement
 


 

To use the calculator:
1. Choose the units of measurement, English or metric.

2. Enter the length of the antenna conductor, which is the distance around the loop. The length should be between 0.1 and 0.25 wavelength at the desired operating frequency.

3. Enter the diameter of the conductor. 
Note: Small transmitting loops have very low radiation resistance and very high circulating current, so the diameter of the conductor must large—around 1" or 2.5 cm for the HF bands—to assure reasonable efficiency. #12 wire will not work.

4. Enter the frequency of operation.

5. Enter the transmitter power. This is optional, but it must be entered if you want to calculate the voltage at the capacitor and the circulating current.

6. Press Calculate.




























RESULTS:
 Antenna efficiency:
Antenna bandwidth:
Tuning capacitance:

Capacitor voltage:
Resonant circulating current:
Radiation resistance:
Loss resistance:
Inductance:
Inductive Reactance:
Quality factor (Q):
Distributed capacity:

Antenna perimeter "circumference:"
Loop dimensions Side length:
Antenna diameter:

Comments:




Input Values:
Length of conductor:
Diameter of conductor:
Frequency:
Transmitter power:

Source:
Basic Equations for a Small Loop in
The ARRL Antenna Book
15th Edition, 1988

References:
The ARRL Handbook

Related Pages:
Design your own tuning capacitor for use with this antenna with the
Capacitance Calculator (Capacitor Design)


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