Optimizing Radiation Patterns of Thinned Arrays with Deep Nulls Fixed through Their Representation in the Schelkunoff...

Area of Science:

• Antenna Theory and Design
• Electromagnetics
• Signal Processing

Background:

• Deep nulls in antenna radiation patterns can degrade system performance.
• Existing methods for null fixing may compromise other crucial antenna characteristics like side lobe level (SLL) and directivity.
• Symmetrical thinned arrays and planar arrays are widely used in various communication systems.

Purpose of the Study:

• To develop an innovative methodology for fixing deep nulls in radiation patterns of symmetrical thinned arrays.
• To maintain a low side lobe level (SLL) and high directivity during the null fixing process.
• To extend the methodology for planar arrays and compare its effectiveness against alternative optimization algorithms.

Main Methods:

• Implementation of an optimization strategy based on the simulated annealing algorithm (SA).
• Definition of a cost function incorporating terms for desired radiation pattern characteristics, distinguishing deep nulls based on the Schelkunoff unit circle.
• Extension of the methodology for planar arrays using a separable distribution procedure.

Main Results:

• Successful fixing of one, two, or three deep nulls in linear arrays of 40, 60, and 80 elements with half-wavelength spacing.
• Demonstration of the methodology's extension to a 40 × 40-element planar array, fixing two deep nulls on each main axis.
• Comparison showing the proposed method's effectiveness against a genetic algorithm (GA) alternative.

Conclusions:

• The developed methodology effectively fixes deep nulls in radiation patterns of symmetrical thinned and planar arrays.
• The method successfully maintains a low side lobe level (SLL) and high directivity.
• A key advantage is the simplified feeding network implementation compared to other techniques.