In this study, a new non-iterative adaptive beamforming (ABF) algorithm for the signal-to-interference and noise ratio (SINR) enhancement is proposed. It is based on a combination between the direction of arrival (DOA...
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In this study, a new non-iterative adaptive beamforming (ABF) algorithm for the signal-to-interference and noise ratio (SINR) enhancement is proposed. It is based on a combination between the direction of arrival (DOA) estimation and the method of moments (mom). The proposed algorithm is denoted as DM/ABF which stands for DOA and mom-based ABF. The DOA is used to provide accurate estimates for the directions of the desired and interfering signals. On the basis of the estimated DOAs, a dedicated shaped pattern version of the ordinary pattern is created and applied as the desired input to the mom algorithm. The mom is used for shaped pattern synthesis to estimate the weights vector required to provide deep nulls toward the interfering signals and directs the main beam toward the desired signal. In this case, the weights vector does not update iteratively at each received signal sample as in case of least mean square (LMS) and recursive least squares (RLSs) algorithms, but it is updated only when the estimated DOAs of the desired and interfering signals are changed. Furthermore, a large number of close nulls can be produced without the need for additional antenna elements compared with other algorithms.
An efficient mom algorithm is introduced to analyse large travelling-wave structures, exemplified with a microstrip leaky wave antenna. The method utilises a combination of travelling-wave and subdomain basis function...
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An efficient mom algorithm is introduced to analyse large travelling-wave structures, exemplified with a microstrip leaky wave antenna. The method utilises a combination of travelling-wave and subdomain basis functions for the current expansion to minimise the number of unknowns in the analysis. The propagation constants which characterise the modal expansions are evaluated efficiently by the algorithm for the implementation of the travelling-wave basis functions. As a result the model overcomes computer memory problems encountered by the conventional mom model in analysing large antennas where a large impedance matrix is needed. The algorithm is capable of generating results as accurate as that of the conventional method while achieving substantial reduction in computation time and resources.
The scattering and absorption of the H and E-polarized plane waves by a flat grating of free standing graphene strips is studied in the THz frequency range. We use the Kubo theory to characterize the surface impedance...
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ISBN:
(纸本)9788393152520
The scattering and absorption of the H and E-polarized plane waves by a flat grating of free standing graphene strips is studied in the THz frequency range. We use the Kubo theory to characterize the surface impedance of graphene and reduce the boundary-value problems to the equivalent integral equations, hyper-singular on the H-case and log-singular in the E-case. Then we discretize them using the projection to the set of orthogonal polynomials;in the H-case these polynomials are chosen to perform the analytical regularization. In each case this technique guarantees fast convergence and controlled accuracy of computations. Reflectance, transmittance, and absorbance of graphene-strip gratings are studied as a function of various parameters. In the H-polarization regime, we find the surface-plasmon resonances and small-scale Rayleigh anomalies. In the E-polarization case, there are no [plasmons however the Rayleigh anomalies become well observable. These results can be considered as reference ones opening way to the accurate modeling of tunable absorbers and frequency selective surfaces based on the periodically patterned graphene layers.
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