Quad ports flexible MIMO antenna with connected ground and high isolation for UWB applications

Abstract

This study proposes a flexible MIMO antenna with improved isolation and connected ground designed on a flexible substrate that makes it compatible with various shapes and surfaces, including curved, irregular, or non-planar structures. The suggested single unit consists of a slotted rectangular radiator on the front layer with a partial ground connected to a circular stub on the other side. As well it is created on a flexible substrate (Rogers RO3003) that has a dielectric constant (ε_r) of 3 and a thickness of 1.52 mm. The Four copies of the single unit with orthogonal orientation are added to improve the system performance. The antenna units are connected through their ground to introduce the connected ground antenna. The size of the proposed design is compact (50 × 50 × 1.524 mm³⁾. The simulating and testing results demonstrate that the antenna operates within a frequency range of 3–12 GHz and achieves a high isolation of ≥ 17 dB over most frequency range. The MIMO parameters and the radiation patterns are analyzed to evaluate the performance of the MIMO antenna. Finally, the four elements of the flexible antenna are fabricated and tested under flat and bending conditions. The simulation and testing results demonstrate that the suggested design exhibits excellent performance, such as broad bandwidth, high isolation, simple structure, and decreased correlation coefficient, which suggest it for the UWB applications and its flexibility allows it for integration into a wide range of devices, such as wearable technology, Internet of Things (IoT) devices, and curved surfaces of vehicles or aircraft.