Improved Beam-Scannable Ultra-Wideband Sparse Antenna Arrays by Iterative Convex Optimization Based on Raised Power Series Representation

Abstract

A novel method is presented to design beam-scannable ultra-wideband (UWB) sparse arrays. A concept of design frequency is introduced which transforms the beam-scannable UWB array design to the problem of synthesizing a broadside-beam array at single-frequency. The raised power series (RPS) representation with appropriate parameter selection is adopted to generate initial element positions, and then an iterative convex optimization is applied to successively optimize the element positions for further sidelobe level (SLL) reduction. Multiple constraints for controlling the first-order Taylor expansion accuracy, the minimum element spacing and the array aperture are incorporated in the iterative convex optimization to obtain stable and practical synthesis results. Several examples for synthesizing UWB arrays with different frequency bands, beam scanning ranges and element counts, are conducted to validate the effectiveness and advantages of the proposed method. It is shown that the proposed method achieves much lower SLLs than those by the original RPS method for all test cases, and it also significantly outperforms some conventional stochastic optimization methods for large UWB array cases.

Synthesis of Large Ultra-wideband Sparse Circular Planar Arrays Based on Rotationally Symmetric Structure

“…For the convenience of the problem description, some notations are given as follows: As we all know, it is more difficult for the UWB array to be synthesized than the narrow-band case due to the consideration of the array pattern over the whole frequency band [𝑓 L , 𝑓 H ]. When the mutual coupling effect is not considered, the peak sidelobe level (PSL) of the array factor at 𝑓 H is the largest PSL over the whole frequency band, varying from 𝑓 L to 𝑓 H [14]. Moreover, it is very critical and difficult for UWB sparse planar array synthesis to meet the minimum element spacing constraint.…”

“…Noticeably, most of these methods focus on the narrowband array case. Certainly, some UWB sparse array synthesis methods have been presented in [12][13][14], but most are limited to linear array and small-scale array. Obviously, it is more difficult for large UWB sparse planar array synthesis, but it was noticed that the usage of some special geometries will contribute to the suppression of grating lobes.…”

Design of a miniaturized ultrawideband and low scattering antipodal vivaldi antenna array

“…For the uniform periodic arrays, one of the methods is using subarray design diagnostics to suppress undesirable grating lobes 24 , and the other is controlling the amplitude distribution of the peripheral array elements to reduce grating lobes 25 . For the aperiodic arrays, it could be realized by optimizing the arrangement of array elements which can offer bandwidths of many octaves with excellent sidelobe suppression 26 , 27 .…”