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Four element patch array with radiation pattern
Patch antenna
Far field polar plot

Problem Description

Microstrip antennas have evolved from simple single substrate, square metallic area structures to highly complex designs incorporating multiple dielectric layers with widely varying electromagnetic properties and complex metallic shapes on different different dielectric layers that couple energy from one layer to the next. The fundamental design principles are highly complex and the influence of minor changes on antenna performance have to be properly investigated before building expensive prototypes. Some of the fundamentals that have to be evaluated by simulation include:

• Coupling efficiency between metallic layers.

• Near-field energy distribution.
• Far-field radiation patterns.
• Current distribution on metallic layers.
• Input impedance.
  

FEKO Solution

FEKO simplifies the design process of microstrip antennas with its comprehensive computational toolset. Full wave Method of Moments (MoM) formulations accurately compute the current distribution on all metallic elements of a microstrip antenna and then compute antenna characteristic parameters from these currents.

Special planar Green's functions are applied to multilayered antennas, enabling the analysis of arbitrarily shaped and oriented metallic surfaces and wires. The metallic structures may even cross dielectric layer boundaries.

Planar Green's functions assume semi-infinite substrates and groundplanes which is perfectly useable for many simulations, but are restrictive for certain problems. This restriction is overcome in FEKO with the application of the surface integral formulation. This technique is applicable to the solution of finite ground plane problems, e.g. where radiation patterns close to the antenna-air boundary is under investigation.

• Voltage sources along wire segments between triangular patches.
• Edge ports at the end of a microstrip feed line.
• Coaxial feed approximation (vertical pin to ground).
• Impressed current source.
• Elementary electrical and magnetic dipoles.
• Plane waves.