An Efficient Near-Field Equivalent Source-Based Internal Multiport Method for Analysis and Optimization of Pixel Antennas

This article introduces an enhanced near-field equivalence mechanism-integrated internal multiport method (IMPM) for the efficient analysis and optimization of pixel antennas. By equating the radiation of internal and external ports to that of homogeneous near-field equivalent source arrays (NFESAs), the design problem of pixel antennas is transformed into the synthesis problem of the NFESA. Furthermore, the principle of pattern multiplication and the fast Fourier transform (FFT) technique are applicable to the synthesis, which can significantly accelerate the far-field calculation and improve the optimization efficiency of pixel antennas. Three antennas are designed and fabricated as examples to validate the advantages of the proposed efficient method against the far-field superposition-based IMPM. By appropriately set the objective function, the first endfire pixel antenna can be directed toward a specific angle at the desired frequency. Subsequently, a low-sidelobe array consisting of heterogeneous pixel elements (HPEs) is proposed and optimized. The proposed array can realize a low sidelobe of −16.6 dB with a uniform feeding network. Finally, a wide-angle scanning phased array with pixel heterogeneous-beam elements is optimized to scan with ±60°. The measured results demonstrate that the proposed pixel arrays with heterogeneous-beam elements can outperform traditional arrays with identical elements. Moreover, the comparison of computation time and accuracy shows that with the expansion of the pixel scales, the new near-field approach exhibits better performance over the far-field superposition technique and enables efficient analysis and optimization of radiation properties of the pixel arrays.