Isophoric Arrays Research Articles

Hybrid Method for the Synthesis of Isophoric Phase-Shaped Beams

A novel hybrid approach to the power synthesis of mask-constrained shaped beams by means of concentric-ring isophoric arrays is presented. The basis of this procedure is to use the complex aperture distribution obtained by Elliott–Stern method as a starting point of an innovative algorithm that combines a classical density tapering method with a simulated annealing one. The proposed technique allows to outperform the previous procedures.

Optimal Synthesis of Shaped Beams Through Concentric Ring Isophoric Sparse Arrays

An innovative deterministic approach to the optimal power synthesis of mask-constrained shaped beams through the concentric-ring isophoric sparse arrays is presented. The design procedure exploits at best the state-of-the-art techniques, respectively, available in the cases of circular-ring isophoric arrays radiating pencil beams and of linear isophoric arrays generating shaped beams. The technique avoids the exploitation of global-optimization algorithms and allows us to significantly outperform all the (few) available procedures.

Hybrid BCS-Deterministic Approach for Sparse Concentric Ring Isophoric Arrays

An innovative methodology for the synthesis of sparse concentric-ring isophoric arrays matching a user-defined reference pattern is proposed. The synthesis problem is recast as a two-step approach firstly aimed at (a) determining the sparsest auxiliary layout of concentric current rings matching the reference pattern through a Bayesian compressive sensing method and successively (b) yielding the concentric-ring isophoric array by means of a density tapering technique. A selected set of numerical experiments is presented to provide some insights about the effectiveness, the numerical efficiency, and the flexibility of the proposed hybrid method.

OPTIMAL SYNTHESIS OF PHASE-ONLY RECONFIGURABLE LINEAR SPARSE ARRAYS HAVING UNIFORM-AMPLITUDE EXCITATIONS

In a large number of applications, including communica- tions from satellites, an optimal exploitation of the available power is of the outmost importance. As a consequence, isophoric array archi- tectures, i.e., arrays using the same power in all the difierent entry points and achieving the ampliflers' maximum e-ciency, are of great interest. At the same time, the easy reconflgurability of the power patterns results fundamental in order to get a full exploitation of the payload. In this paper, an innovative and deterministic approach is proposed for the optimal synthesis of linear phase-only reconflgurable isophoric sparse arrays able to commute their pattern amongst an arbi- trary number of radiation modalities. The introduced perspective leads to an efiective solution procedure for the fast design of antennas with high performance, and does not recur to computationally expensive global-optimization techniques. Numerical results concerning applica- tions of actual interest and employing realistic element patterns are provided in support of the given theory.

Isophoric arrays-massively thinned phased arrays with well-controlled sidelobes

Traditional filled phased arrays have an element placed in every location of a uniform lattice with half-wavelength spacing between the lattice points. Massively thinned arrays have fewer than half the elements of their filled counterparts. Such drastic thinning is normally accompanied by loss of sidelobe control. This paper describes a class of massively thinned linear and planar arrays that show well-behaved sidelobes in spite of the thinning. The term isophoric is derived from Greek roots to denote uniform weight. In isophoric arrays, element placement based on difference sets forces uniformly weighted spatial coverage. This constraint forces the array power pattern to pass through V uniformly spaced, equal, and constant values that are less than 1/K times the main beam peak, where V is the aperture size in half-wavelengths and K is the number of elements in the array. The net result is reduced peak sidelobes, especially when compared to cut-and-try random-placement approaches. An isophoric array will exhibit this sidelobe control even when the array has been thinned to the extent that K is approximately the square root of V. Where more than one beam must be generated at a time, isophoric array designs may be used to advantage even within a traditional filled array. By interweaving two isophoric subarrays within a filled array and by appropriate cyclic shifting of the element assignments over time, two independent antenna power patterns can be generated, each with a sidelobe region that is approximately a constant value of 1/(2K) relative to the main beam, where K is the number of elements in the subarray.