Broadband multiple‐input–multiple‐output antenna using castor leaf‐shaped quasi‐self‐complementary elements

Abstract

In this study, the simulation and experimental studies of a single-sided broadband multiple-input–multiple-output (MIMO) antenna with and without dual band-rejection characteristics are discussed. The proposed antenna consists of two castor leaf-shaped quasi-self-complementary elements, which are arranged side-by-side in mirror-image configuration. The antenna provides good isolation between its ports without using any isolation technique. The simulated and experimental impedance bandwidths of optimally designed antenna are 142.5% (2.2–13.1 GHz) and 133.3% (2.6–13.0 GHz), respectively. The overlapping communication bands, worldwide interoperability for microwave access and wireless local area network are rejected using two resonators: a slit and a hexagonal-split-ring slot loaded on radiating patches. For both the antennas, mutual coupling (S 21) between ports and envelope correlation coefficient are <−15 dB and 0.02, respectively, over the operating frequency band. The antenna elements radiate in opposite directions due to their mirror-image configuration, when excited individually through the source while the non-excited antenna port is match-terminating. The antenna exhibits good peak realised gain and total efficiency over its operating bandwidth, and when loaded with two resonators, it shows a decrease of gain as well as efficiency around the rejected frequency bands. The proposed antenna can be utilised for devices requiring ultra wideband along with Bluetooth frequency spectrum.