This paper presents a novel composite phase unit (CPU) designed for an orbital angular momentum (OAM) metalens (ML), featuring a 3D-printed middle metal layer (MML) with non-uniform height. This design reduces slot length variations and mitigates bandwidth shrinkage resulting from passband overlap. It also aligns the frequency response of each CPU, ensuring that peak transmission occurs at the center frequency. The CPU consists of an MML sandwiched between two polarization grids (PGs), forming a quasi-Fabry-Pérot (FP) cavity. A high-resonance metal slot structure within the MML improves the transmission amplitude. To achieve a full 2π phase shift range, the CPU combines propagation, geometric, and resonant phase-control mechanisms. The non-uniform-height MML is fabricated via selective laser melting (SLM) using AlSi10Mg, which demonstrates the capability of 3D printing to fabricate complex structures. Experimental results show that the ML achieves a measured gain of 26.81 dBi at 36 GHz and a 3-dB gain bandwidth of 16.2%, representing significantly improved bandwidth retention relative to the CPU’s 3-dB transmission bandwidth of 12.8%. The proposed OAM metalens demonstrates high mode purity and stable transmission, which enables efficient multichannel wireless communications that are critical for Internet of Things (IoT) applications. This structure significantly improves link capacity, energy efficiency, and system-level simplicity in multichannel IoT systems.

Abstract This article proposes an electrically small, probe-fed Ultra-Wideband (UWB) monopole antenna on a slotted truncated ground plane for breast cancer detection. The physical footprint of the proposed antenna element is 33 mm × 35 mm × 0.5 mm. This element is designed on the low-cost FR4 Epoxy substrate with a thickness of 0.5 mm. The proposed antenna has an electrical size of 0.33λ × 0.35λ × 0.005λ at the lowest frequency of operation; the radiator offers an impedance bandwidth of 8.34 GHz, which implies a fractional bandwidth of 115.5%. A compact dual-polarized antenna topology with two orthogonally placed probe-fed monopole antennas is proposed to achieve polarization diversity. The impedance characteristics of the individual radiating elements are maintained in spite of the electrical proximity of the radiators. The numerically computed and experimentally measured results of dual-polarized electrically small UWB antenna agree quite well. The proposed dual-polarized antenna topology is investigated for its utility in breast cancer detection in simulation.