Plotting Radiation Patterns for Uniform Linear Arrays and Uniform Circular Arrays Using MATLAB

Fundamental Principles of Antenna Array Pattern Plotting

Radiation patterns provide graphical representations of antenna array radiation characteristics, displaying radiation intensity in different directions. Uniform linear arrays (ULA) and uniform circular arrays (UCA) are two common antenna array configurations widely used in radar systems, communication technologies, and acoustic applications. In MATLAB, we can utilize either the Phased Array System Toolbox or fundamental mathematical computations to generate their radiation patterns.

Uniform Linear Array (ULA) Radiation Pattern A ULA consists of equally spaced antenna elements, and its radiation pattern can be calculated by superimposing the radiation fields from individual elements. Key parameters include element spacing, wavelength (or frequency), and excitation amplitude and phase. The pattern is typically displayed in polar or Cartesian coordinates, with main lobe direction determined by phase differences. MATLAB implementation involves calculating array factor using element phase shifts based on spatial geometry.

Uniform Circular Array (UCA) Radiation Pattern UCA elements are uniformly distributed along a circular circumference, providing symmetric patterns suitable for omnidirectional or specific beamforming requirements. Pattern computation must account for geometric position variations among elements, potentially resulting in multiple beams or circular radiation characteristics. The implementation requires calculating phase contributions from each element's angular position.

MATLAB Implementation Approach Parameter Definition: Set parameters including number of elements, spacing, operating frequency, and array geometry. Phase Calculation: Compute phase compensation for each element based on wave path differences using trigonometric functions. Pattern Synthesis: Superimpose radiation fields from all elements to obtain the total radiation pattern through vector summation. Visualization: Utilize `polarplot` for basic pattern display or `patternCustom` from the Phased Array System Toolbox for advanced 3D pattern visualization with customizable parameters.

By adjusting parameters (such as element count and spacing), users can observe pattern characteristics including main lobe narrowing and sidelobe suppression, facilitating comprehensive array performance analysis. Code implementation typically involves azimuth/elevation angle sampling, array factor computation, and normalization for proper pattern scaling.