Multiple independent radio-frequency (RF) beams find applications in communications, radio astronomy, radar and microwave imaging. An N-point fast Fourier transform (FFT) applied spatially across an array of receiver ...
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Multiple independent radio-frequency (RF) beams find applications in communications, radio astronomy, radar and microwave imaging. An N-point fast Fourier transform (FFT) applied spatially across an array of receiver antennas provides N-independent RF beams at N/2 log(2) N multiplier complexity. Here, a low-complexity multiplierless approximation for the 8-point FFT is presented for RF beamforming, using only 26 additions. The algorithm provides eight beams that closely resemble the antenna array patterns of the traditional FFT-based beam-former albeit without using multipliers. The proposed FFT-like algorithm was verified on-chip using a Xilinx Virtex-6 Lx240T field programmable gate array (FPGA) device. The FPGA implementation indicated bandwidth of 369 MHz for each of the independent receive-mode RF beams.
We review and formalize the mathematical background of time-modulated linear arrays (TMLAs);then, a number of issues are examined. First, for signal transmission applications, restrictions to the frequencies involved ...
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We review and formalize the mathematical background of time-modulated linear arrays (TMLAs);then, a number of issues are examined. First, for signal transmission applications, restrictions to the frequencies involved in the procedure are highlighted. Second, the sideband power losses associated to the technique are thoroughly examined, introducing a coefficient appropriate to evaluate the efficiency of the procedure. Finally, a closed form expression for the total power associated to sideband radiation is obtained, very convenient for the implementation of real-time optimization of the system. Relevance of additional research on the subject is highlighted.
In this paper. tune modulation is applied to a small number of elements of a linear array that radiates either sum or difference pattens, in order to take control over their sidelobe levels. The simulated annealing (S...
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In this paper. tune modulation is applied to a small number of elements of a linear array that radiates either sum or difference pattens, in order to take control over their sidelobe levels. The simulated annealing (SA) technique helps to obtain the optimum time pulses applied to such elements in terms of sideband immunization. (c) 2006 Wiley Periodicals, Inc.
It is shown in this paper that when artificial neural networks are extended to be complex valued, they can be incorporated as a very powerful and effective tool in the analysis, synthesis, and diagnostics of antenna a...
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It is shown in this paper that when artificial neural networks are extended to be complex valued, they can be incorporated as a very powerful and effective tool in the analysis, synthesis, and diagnostics of antennaarrays. (c) 2006 Wiley Periodicals, Inc.
This letter shows that, by the proper use of time modulation in equispaced linear arrays with uniform excitation distribution, it is possible to maintain the sidelobe zone of the radiated power under certain-previousl...
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This letter shows that, by the proper use of time modulation in equispaced linear arrays with uniform excitation distribution, it is possible to maintain the sidelobe zone of the radiated power under certain-previously stipulated-level whereas the undesired harmonics are minimized. In addition to that, the further extension of the technique to nonequispaced arrays permits to obtain broadband response, by simply searching the positions of the elements that reach to the desired power pattern behavior within the required bandwidth.
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