New Configurations of Low-Cost Dual-Polarized Printed Antennas for UWB Arrays
The development of ultra-wide-band (UWB) antennas is recently providing new solutions for the design of innovative, versatile, and economical radar and communication systems. A novel class of structures is proposed and optimized for the purpose of producing ultra-wide-band radiating elements for large arrays, providing dual polarization, beam scanning, and compact and inexpensive realization based on suitable rhombic arrangements of dipoles printed on low-cost layered substrates. The two structures presented here are based on various arrangements of printed dipoles of different lengths forming approximately rhombic-shaped elements. The central patch is the longest and can be fed at its ends with one or two probes; the side patches, being six or eight depending on the structure, have smaller dimensions and are parasitic. To further increase the bandwidth, the dipoles are printed on a three-layer structure, designed with low-cost commercially available dielectric substrates. In a first implementation, four rhombic shapes, orthogonally placed on the same layer, provide two orthogonal polarizations.
In a second implementation, the two polarizations are excited by two rhombic shapes printed on two different layers in a stacked-patch-like arrangement. This latter structure leads to a better lateral shielding of the single radiating element, in order to reduce mutual interactions among adjacent elements in array environment. An optimization procedure, involving the dimensions of the patches and the positions of the feeding probes, has been carried out with modeFRONTIER with the aim of achieving the best input matching the desired frequency band. The optimization has been performed at first on a single rhombic shape and then refined with the full four-rhombus structure. The algorithm used is a multi-objective genetic algorithm with multisearch elitism for enhanced robustness, while the results presented in the paper have been computed with the time-domain solver of the high-frequency electromagnetic CAD CST Studio 2010.