Design and Analysis of Compact MIMO Patch Antennas with High Gain and Bandwidth for 5G FR1 _ FR2 Applications

Abstract

Future 5G wireless communication systems require high data rates, low latency, and strong reliability. In 5G New Radio (NR), the frequency bands are divided into two main ranges: FR1 and FR2. FR1 spans from 410 MHz to 7125 MHz, while FR2 is further split into two sub-bands FR2-1, which covers 24.25 GHz to 52.6 GHz, and FR2-2, which ranges from 52.6 GHz to 71 GHz. Multiple Input Multiple Output (MIMO) technology and antenna arrays are widely used for 5G NR bands to enhance channel capacity, boost transmission speed, and support high data rates. However, at FR2 frequencies, propagation and atmospheric losses become significant, necessitating high-gain and wide-bandwidth antennas to counter these effects. Vivaldi and antipodal Vivaldi antennas are well-suited for these requirements, as they provide the high gain and wide bandwidth essential for reliable, high-performance 5G communication. newlineThe study begins with the design of a simple 1x2 MIMO microstrip elliptical patch antenna at 3.5 GHz for 5G applications, focusing on key MIMO characteristics such as Envelope Correlation Coefficient (ECC), Diversity Gain (DG), Channel Capacity Loss (CCL), Total Active Reflection Coefficient (TARC), Mean Effective Gain (MEG), and MEG Ratio. The antenna elements are arranged orthogonally to enhance isolation and minimize mutual coupling, a crucial factor in MIMO performance. Following this, a 2x2 Vivaldi MIMO antenna is developed for 5G (FR1) at 3.5 GHz, yielding an improved gain over the elliptical patch antenna. A Vivaldi shape is etched onto the ground plane as a Defected Ground Structure (DGS), with additional slits in the ground plane for optimal matching. newlineTo further enhance gain and bandwidth, the Vivaldi MIMO antenna is adapted for 5G FR2 frequencies, starting with a 2x2 design at 28 GHz and 39 GHz, where gain and bandwidth improvements are achieved without additional slits, maintaining a Vivaldi shape etched on the ground plane.