Reflector Antennas

Reflector antenna
Reflector near-field

Reflector antennas are typically used when very high gain (e.g. satellite transmission or reception) or a very narrow main beam (e.g. secure communication) is required. Gain is improved and the main beam narrowed with increase in the reflector size.  Large reflectors are, however, difficult to simulate as they become very large in terms of wavelength.

FEKO is well suited to the numerical analysis of reflector antennas and provides the following techniques as options for reflector simulation:

• Multilevel Fast Multipole Method (MLFMM): This is an efficient version of the MoM, suited to multi-wavelength structures. This full-wave method yields very accurate results.
  
• Physical Optics (PO): The PO high frequency approximation can be used to approximate current flow on the reflector. This techniques is computationally less expensive than the MLFMM and most suited when the feed and reflector can be considered as decoupled. Continuous current flow can be modelled from standard MoM regions to PO regions.
  
• Ray launching Geometrical Optics (GO): The GO is even less expensive than the PO and is also a high frequency approximation method. It can take multiple reflections very easily into account as it is based on shooting and bouncing rays. Continuous current flow cannot be modelled from standard MoM regions to PO regions.
• Uniform Theory of Diffraction (UTD): With this high frequency approximation method, computational cost is independent of reflector size, but only flat plates can be considered.

Users with limited computational resources or with an interest in extremely large reflectors find the high frequency approximation techniques particularly useful. To keep computational costs down, domain decomposition can be used. The feed antenna is simulated in isolation and the result is then used to replace the feed antenna with an equivalent source when simulating the reflector.