Use of the Generalized Vector Addition Theorem for Antenna Position Translation for Spherical Mode-Filtering-Based...

Area of Science:

• Electromagnetics and Antenna Theory
• Electromagnetic Compatibility (EMC)
• Measurement Science and Technology

Background:

• Monochromatic mode-filtering is effective for scattering suppression in antenna and Radar Cross-Section (RCS) measurements.
• Traditional methods require transformation to the far-field, involving complex computations and potential information loss, especially for spherical near-field (SNF) measurements.
• Existing vector addition theorem implementations for SNF are limited in translation direction and magnitude relative to the minimum sphere radius.

Purpose of the Study:

• To introduce a novel, rigorous algorithm for direct application of antenna under test (AUT) displacement in spherical near-field measurements.
• To develop an efficient implementation that integrates seamlessly into standard SNF data processing.
• To extend the applicability of the vector addition theorem for SNF transformations to arbitrary translation directions and magnitudes.

Main Methods:

• Development of a new algorithm utilizing the vector addition theorem for spherical waves to directly apply AUT displacement.
• Efficient implementation of the translation and filtering algorithm within the SNF data processing chain.
• Derivation of a generalized vector addition theorem applicable to arbitrary translation directions and magnitudes, including cases smaller than the minimum sphere radius.

Main Results:

• The novel algorithm successfully applies AUT displacement directly, bypassing the need for transformation to the asymptotic far-field.
• The method eliminates the requirement for secondary spherical wave expansions and summations, reducing computational effort.
• The generalized vector addition theorem enables translations in any direction and for displacements smaller or larger than the minimum sphere radius.

Conclusions:

• The proposed algorithm offers a more efficient and rigorous approach to scattering suppression in spherical near-field measurements.
• This method simplifies the data processing chain for SNF transformations, avoiding computational overhead and information loss associated with far-field conversion.
• The generalized vector addition theorem significantly enhances the flexibility and applicability of SNF measurement techniques.