Loop Antenna Calculator and Formula

This page explains the loop antenna and provides a calculator based on the loop antenna formula. We’ll cover how to use the calculator and the formulas behind it.

What is a Loop Antenna?

A loop antenna is a type of RF antenna constructed from a wire loop. These loops can take various shapes, most commonly circular or rectangular. To achieve specific performance characteristics like directivity, efficiency, and radiation pattern, a loop antenna can consist of a single turn or multiple turns of wire.

Different types of loop antennas exist, including small loops, large loops, and magnetic loops.

The figure below shows examples of circular and rectangular loop antennas, along with their typical radiation patterns.

Loop antennas are popular in amateur radio (AR), shortwave listening (SWL), and other RF applications. They are often favored due to their compact size and light weight.

Basic specifications to consider when selecting a loop antenna include:

• Frequency range of operation
• Impedance
• Power rating (Maximum)
• Loop diameter
• Loop Height
• Number of turns
• Other parameters: Weight, connectors, dimensions, tuning control, etc.

Loop Antenna Calculator

Here’s how to use the loop antenna calculator with an example:

EXAMPLE:

INPUTS:

• Operating Frequency (MHz) = 15 MHz
• Loop diameter (cm) = 120 cm
• Loop capacitance (pF) = 0.1
• Loop inductance (µHenry) = 2.6
• Loop resistance (Ohm) = 50

OUTPUTS:

• Loop Circumference = 3.77 meters
• Loop Area = 1.13 m²
• Loop Height = 1.2 meter
• Loop Feed point location = 0.94 meter
• Loop Resonance Frequency = 312 MHz
• Loop Quality Factor = 4.9

Loop Antenna Formula

The following loop antenna formulas or equations are used in the loop antenna calculator above.

This calculator is a useful tool for designing loop antennas and determining their parameters.