Phenomenological modeling of circular arrays of dipole-antennas

Abstract

In an array of antennas, the inter-antenna mutual coupling can greatly affect the array's overall performance in various application, such as direction-of-arrival (DOA) estimation and beamforming. For a uniform circular array (UCA) of identical dipoles oriented perpendicular or radial to the circle plane, this thesis advances a simple expression of their electromagnetic mutual impedance, in simple closed forms, explicitly in terms of the dipoles' length (L), the number (M) of dipoles comprising the array, and the circular array grid's radius (R). This simple model is obtained via a "behavioral" (a.k.a. "phenomeno-logical" or "block-box") approach, which is new to UCA inter-antenna mu-tual coupling modeling. This "phenomenological" or "behavioral" approach takes mutual impedance data, (generated by Method-of Moments (MoM) electromagnetic simulations) to fit into a low-dimensional manifold. Such an approach is commonplace in modeling wireless fading channels and the nonlinear amplifier's input/output relationship, though admittedly can be used to mutual coupling modeling. Despite the conceptual simplicity of this approach, subsequently presented results will demonstrate its success to yield simple rule-of-thumb relationships of how the mutual impedance varies with the wavelength-normalized dipole length (L/λ), the number M of such dipoles in the circular array, and the circle's radius (R/λ).