Home arrow Electronics & Computers arrow Progress in Canted Sector Antennas and Non-Periodic Arrays
Progress in Canted Sector Antennas and Non-Periodic Arrays Print E-mail
Army Research Laboratory, Adelphi, Maryland   
Jun 01 2007
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Figure 2. This Periodic Array of four random subarrays would offer sidelobe performance approaching that of a fully random array of the same size, but would cost less than does the random array.
In principle, antennas can be positioned in random arrays to improve sidelobe performances. Because it may prove too costly to fabricate truly random arrays, in some applications it might be cost-effective to construct less-expensive pseudorandom arrays that exhibit acceptable sidelobe performances over specified frequency ranges. The approach taken in this development effort is to use random subarrays as building blocks of larger pseudorandom arrays. This approach admits of variations, including periodic arrays of random subarrays (PARS, depicted in Figure 2), arrays of periodically rotated random subarrays (ARRS-P), and arrays of randomly rotated random subarrays (ARRSR). Computational simulations have shown that for an array of a given aperture size and number of elements, the PARS approach offers the robust wideband performance of a random array in a geometrically simpler design, but with sidelobes somewhat higher than those of a purely random array of the same size. Sidelobe performance can be improved somewhat by progressing from PARS through ARRS-P to ARRS-R.

The software used to perform the computational simulations implements a marching-on-time, method-ofmoments algorithm for solving a timedomain electric-field integral equation of an antenna. Given a band-limited excitation, the algorithm solves for surface currents induced on the radiating element and the ground plane. For a geometry modeled by use of Ns surface unknowns and Nt time steps, the number of arithmetic operations required by the algorithm scales as O(NtN2s {where “O(x)” signifies “of the order of x”}. The algorithm can be augmented by use of a parallel-processing fast-Fourier-transform (FFT)-based accelerator, reducing the number of arithmetic operations to O(NtNs[log(Ns)]2). The software employs a standard message-passing interface for communication among processors and utilizes the Fastest Fourier Transform in the West (FFTW) library [a publicly available subroutine library for computation of parallel FFTs]. This software makes it possible to analyze the broadband characteristics of antennas characterized by Ns >105, using supercomputers comprising tens of processors, in practical amounts of time.

This work was done by Jennifer T. Bernhard, Paul E. Mayes, Eric Michielssen, Garvin Cung, and Kiersten Kerby of the University of Illinois for the Army Research Laboratory. For more information, download the Technical Support Package (free white paper) at www.defensetechbriefs.com/tsp under the Electronics/Computers category. ARL-0011

This Brief includes a Technical Support Package (TSP).

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