The solution to their problem is to consider distant antenna-elements spaced by d ≫ λ.
Otherwise, for accurate AS estimation, we consider the distant antenna-elements (d ≫ λ) with a correlation coefficient amplitude higher than 0.05.
In other terms, we exploit only distant antenna-element pairs for which the correlation coefficient magnitude is higher than 0.05.
During simulations, we noticed that the standard deviations of the AS estimates obtained using distant antenna-elements offer lower error probability of distribution type selection.
The final AS estimate is the mean of the AS estimates over distant antenna pairs associated with γ ^ f, i.e., the estimated AS is σ ^ θ = mean σ ̃ i k ( d ) ( γ ^ f ).
Otherwise, we compute the standard deviations of the estimated AS obtained using the distant antenna-elements ( σ ̃ i k ( d ) : σ a s = std σ ̃ i k ( d ) ; ( i, k ) such that d i k ≫ λ and | R ^ i k | > 0. 0 5. (31).
As one can conclude, the array structure has to have two main properties: the nonlinearity for the distribution type selection and the existence of distant antenna-elements for a high estimation accuracy in the case of small AS.
Since our nonlinear structure presents distant antenna-elements spaced by 3λ, we consider a ULA with seven elements spaced by λ 2. Note that while a ULA configuration can estimate AS values higher than 10°, the functions Λ of the butterfly and (0-1-3) structures show lower limits.
For the case where the EM source is sufficiently distant from the antenna array to be approximated as a plane wave, the slope of the fitted line corresponds to the incident angle against the baseline of the antennas.
An odour delivery glass tube (2.0 cm i.d). was positioned approximately 1.0 cm distant from the antennae.
These two metrics are mathematically related to each other when considering locations many wavelengths distant from the antenna (or the RF source).
