3. Small Loops

The small word means that the antenna is actually electrically small. The most commonly used electrical small definition is that the maximum size of the antenna is less than one-tenth of the wavelength. For loop antennas, it means that the diameter is smaller than one-tenth of the wavelength (\(D\le\lambda/10\)).

In the case of loop antennas, the dipole consists of a usually circular or rectangular current loop which acts like a coil and functions in response to the magnetic component of the electromagnetic field [44].

A small loop (circular or square) is equivalent to an infinitesimal magnetic dipole whose axis is perpendicular to the plane of the loop. That is, the fields radiated by an electrically small circular or square loop are of the same mathematical form as those radiated by an infinitesimal magnetic dipole [8].

Breed carried out an article on electrically small antennas. Here, the electrically small antenna was defined and then the application areas were explained in detail. Starting with radiation resistance, then other loss parameters that affect efficiency were mentioned. The important points to be considered when impedance matching were indicated [9].

• 3.1. Introduction
• 3.2. Radiated Fields
  • 3.2.1. Thin Wire, Constant Current, Small Circumference
• 3.3. Loop Geometry
  • 3.3.1. Dimensions
  • 3.3.2. Coil cross-section advantage/disadvantage
• 3.4. Impedance of a Small Loops
  • 3.4.1. Over a Conducting Medium
• 3.5. Receiving Signal
• 3.6. Signal to Noise Ratio (SNR)
  • 3.6.1. Rx
  • 3.6.2. Transformer coupled
  • 3.6.3. Direct Connected