Direction finding and mutual coupling estimation for uniform rectangular arrays

A novel two-dimensional (2-D) direct-of-arrival (DOA) and mutual coupling coefficients estimation algorithm for uniform rectangular arrays (URAs) is proposed. A general mutual coupling model is first built based on banded symmetric Toeplitz matrices, and then it is proved that the steering vector of a URA in the presence of mutual coupling has a similar form to that of a uniform linear array (ULA). The 2-D DOA estimation problem can be solved using the rank-reduction method. With the obtained DOA information, we can further estimate the mutual coupling coefficients. A better performance is achieved by our proposed algorithm than those auxiliary sensor-based ones, as verified by simulation results

Direction finding in the presence of a more realistic environment model

Direction-of-arrival (DOA) estimation is susceptible to errors introduced by the presence of real-ground and resonant size scatterers in the vicinity of the antenna array. To compensate for these errors pre-calibration and auto-calibration techniques are presented. The effects of real-ground constituent parameters on the mutual coupling (MC) of wire type antenna arrays for DOA estimation are investigated. This is accomplished by pre-calibration of the antenna array over the real-ground using the finite element method (FEM). The mutual impedance matrix is pre-estimated and used to remove the perturbations in the received terminal voltage. The unperturbed terminal voltage is incorporated in MUSIC algorithm to estimate DOAs. First, MC of quarter wave monopole antenna arrays is investigated. This work augments an existing MC compensation technique for ground-based antennas and proposes reduction in MC for antennas over finite ground as compared to the perfect ground. A factor of 4 decrease in both the real and imaginary parts of the MC is observed when considering a poor ground versus a perfectly conducting one for quarter wave monopoles in the receiving mode. A simulated result to show the compensation of errors direction of arrival (DOA) estimation with actual realization of the environment is also presented. Secondly, investigations for the effects on received MC of λ/2 dipole arrays placed near real-earth are carried out. As a rule of thumb, estimation of mutual coupling can be divided in two regions of antenna height that is very near ground

Low Cost Direction Finding with the Electronically Steerable Parasitic Array Radiator (ESPAR) Antenna

Faculty of Engineering and the Built Environment; School of Electrical and Information System; MSC DissertationIn this paper, the Electronically Steerable Parasitic Array Radiator (ESPAR) antenna, developed by the Advanced Telecommunications Research Institute (ATR) in Japan was analyzed to determine its feasibility as a low cost direction finding (DF) system. Simulations of the antenna were performed in SuperNEC and Matlab was used to determine the direction of arrival (DOA) using the Reactance Domain multiple signal classification (MUSIC) algorithm. Results show the ideal configuration has 6 parasitic elements with a diameter of 0.5 . Up to 5 periodic, uncorrelated signals spread 360° in azimuth and above 45° elevation produce sharp peaks in the MUSIC spectra. Azimuth separations of only 2° at 40 dB are resolvable while signals arriving with 25% full power are still detectable. For the DOA to be resolved the radiation pattern should be asymmetrical and hence the reactance set should have a range of unequal values. Comparative results show that the 6 element ESPAR offers excellent overall performance despite the reduction in cost and is comparable in performance to the 6 element uniform linear array

Slot loss and coupling studies in stacked linear array applications

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