Distributed-elements systems can be used for modelling and/or analysis of:

• Systems that can be considered as linear
  Condition fulfilled under small-signal conditions
• Systems with propagation effects
  System dimensions to wavelength ratio is comparable with 1

One-Dimensional Systems

• Dimensions on the plane perpendicular to the longitudinal axis are small compared with the wavelength
• System parameters can be functions of the length coordinate:
  • Cross-section
  • Coefficient of absorption
  • Electric resistance per unit length
  • ...

• Examples of one-dimensional systems
  • Mechanical
    • String
    • Bar
  • Acoustic
    • Tubes

Two-Dimensional Systems

• Systems possessing two dimensions that are large in comparison to the third one

• Examples of two-dimensional systems
• Mechanical
• Plates
• Membranes
• Acoustic
• Slots

Three-Dimensional Systems

• The most general description must be used to study the propagation of mechanical or acoustic waves
• in an anisotropic medium
• or to describe the propagation in three dimensions