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Fractal Antenna Design, Working, and Benefits

antenna fractal geometry rf design wireless

This page covers the basics of fractal antennas, including their design, working operation, and benefits.

Introduction

Traditionally, antennas are designed for specific applications and frequencies. However, fractal antennas are designed for use across multiple frequency bands and applications. Their unique characteristics stem from the geometry and design of fractals. Fractal geometry-based shapes are found in nature and have applications in image compression, lightning, and more.

Fractal Antenna Geometry Fractal Antenna Geometry

The following table lists types of fractal geometries and their unique characteristics. These geometries are used in fractal antenna design, as explained below.

Fractal Geometry typeDescription
Sierpinski GasketUses triangles during design. Black areas represent metallic conductors, and triangular areas represent regions where metal has been removed.
Sierpinski CarpetUses squares instead of triangles.
Koch CurvesStarts with a straight line partitioned into 3 parts. The middle segment is replaced with two others of the same length. The first iteration is known as the generator. Higher numbers of iterations produce other geometric constructions.
Cantor SetProduced using algorithms. The set becomes sparser as the number of iterations increases.

Benefits of Fractal Antennas

Applying the fractal concept to antenna elements offers the following advantages:

  • Smaller antenna size with excellent efficiency and gain.
  • Resonance frequencies supporting multiple bands.
  • Easy optimization for target gain values.
  • Wideband frequency response.
  • Simple and robust design, with characteristics dependent on geometry rather than discrete components.

Fractal Antenna Working and Design

Different feeding techniques can be employed in antenna design, each with its own advantages and disadvantages, including:

  • Microstrip Line feeding
  • Coaxial Probe feeding
  • Aperture Coupled feeding
  • Proximate Coupled feeding
  • CPW feeding

Sierpinski carpet Fractal Antenna Sierpinski carpet Fractal Antenna

Let’s take the example of a Sierpinski Carpet Antenna with CPW feeding to understand the working operation of a fractal antenna.

The figure above depicts a fractal antenna using Sierpinski carpet geometry. Usually, the ground plane geometry is kept fixed, and the radiating patch structure on top is varied to obtain different radiation patterns and bandwidth. This type of antenna is suitable for WLAN applications to support multiple frequency bands, such as 2.4 GHz, 5.2 GHz, and 5.5 GHz. It can also be used for WiMAX devices operating in frequency bands like 2.5 GHz, 3.5 GHz, and 5.5 GHz.