Electrically “Long” Dipoles in a Collocated/Orthogonal Triad—for Direction Finding and Polarization Estimation

In dipole-antenna array signal-processing algorithm development, research has focused on “short dipoles” whose physical length (L) is under (1/10) of a wavelength λ. Such electrically “short” dipoles have very small input impedances, rendering such “short” dipoles to be inefficient radiators. Practical dipoles, with an electrical length of (L/λ) ∈ [0.1, 1], have notably larger input impedance, hence making them better radiators. Of such practical dipoles, this paper investigates their use for azimuth-polar direction finding and for polarization estimation. This paper will first present the measurement model (i.e., array manifold) of a triad of such practical dipoles, collocated in space and orthogonally oriented. This paper will then develop the corresponding closed-form algorithms to estimate the bivariate azimuth-elevation direction-of-arrival or the bivariate polarization. Such closed-form algorithms previously have been unavailable in the existing literature for such a triad of electrically “long” dipoles of pragmatic radiation efficiency.