Data-Driven Bayesian Optimization Framework for Rapidly Developing Novel Wideband, Low-Profile Dipole Antenna With 3-D-Printed Technology

This article presents an innovative framework for fast-developing broadband, low-profile, dual-polarized cross-dipole antennas. This approach integrates a broadband, petal-shaped cross dipole with a 3-D-printed structure comprising multilayers of high-permittivity material with varying heights and radii. In the absence of a theoretical model and a satisfactory initial design, the design process employs the enhanced tree-structured Parzen estimator Bayesian optimization (TPE-BO) algorithm, a significant advancement over traditional Bayesian methods, for effective hyperparameter tuning to streamline the design. The proposed method only adjusts the high dielectric constant loading (HDL) structure without changing the original dimensions of the dipole. Compared with conventional optimization algorithms integrated within CST, this method efficiently achieves the desired broadband and low-profile performance. Meanwhile, the mechanism of the HDL structure in increasing the bandwidth (BW) while enabling the dipole’s low-profile performance is explained. The proposed approach has been validated by fabricating and measuring a hybrid antenna prototype. The measured results show that the antenna achieves an overlap BW between the impedance matching BW and the 3-dB gain BW of 79.3% (from 1.62 to 3.75 GHz) with a voltage standing wave ratio (VSWR) of less than 1.6. In addition, the isolation between the two ports exceeds 20.5 dB. Significantly, this HDL technique notably enhances the BW and reduces the antenna’s profile from <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.2\lambda _{L}$ </tex-math></inline-formula> to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.1\lambda _{L}$ </tex-math></inline-formula> compared with a single-petal-shaped cross dipole. Thus, this study provides a simple, effective, and repeatable design strategy for realizing broadband and low-profile performance in dipole antennas.