antena de microfita de dupla polarização de alto ganho e banda larga baseada em perturbação modal e ressonadores de 𝜆/4

Abstract

This work presents the design, analysis, and experimental validation of a dual-polarized square microstrip patch antenna with enhanced bandwidth and realized gain. The proposed antenna operates under modified TM10 and TM01 modes, which are independently excited through two orthogonal feed ports. The gain enhancement is achieved by incorporating four metallic vias symmetrically positioned between the radiator and the ground plane; this configuration perturbs the electromagnetic field distribution within the substrate, making the antenna electrically larger relative to the resonant wavelength. Simultaneously, bandwidth enhancement is attained through a feeding system composed of pairs of quarter-wavelength (𝜆𝑔/4) microstrip line resonators. These resonators introduce an additional resonance associated with the feed network, functioning as an integrated filter that, when properly coupled to the modified fundamental mode of the patch, results in a significant expansion of the impedance bandwidth. Unlike conventional approaches, this work integrates both techniques into a single dual-polarization architecture while maintaining the structure’s compactness and low profile. The design process was optimized using the Finite Element Method (FEM), followed by the fabrication and characterization of a prototype on a Rogers CuClad 250GX substrate. Experimental results demonstrated excellent agreement with computational predictions. The final device achieves a fractional bandwidth of approximately 7.5% (6.93–7.47 GHz) for |𝑆𝑛𝑛| ≤ −10 dB. At the 7.25 GHz operating frequency, the antenna exhibits a peak realized gain of 10.3 dBi, port-to-port isolation greater than 25.0 dB, and cross-polarization discrimination of 22.2 dB. Additionally, time-domain analyses confirm that the dispersive parameters and group delay of the structure do not impose significant limitations on digital communication system performance.