Switchable/Tunable Band-Notched Characteristics in UWB and UWB-MIMO Antennas: A Comprehensive Review

The objective of this study is to give a deep knowledge on band notched reconfigurability in ultra-wideband (UWB) and ultra-wideband multi-input multi-output (UWB-MIMO) antennas. Reconfigurability over notched bands refers to having switchable and tunable notched properties. It is well known that the UWB system undergoes several narrow band interferences. Therefore, rejection of interferences is a challenging task which in turn becomes more challenging when there is a requirement of reconfigurable notched property. Different techniques for realizing single/dual/triple notched-band functions are broadly discussed. Further, to investigate various approaches and techniques for realizing reconfigurability in UWB and UWB-MIMO antennas an exhaustive review of the existing literature is conducted. Based on their notched realizing techniques UWB reconfigurable antennas are broadly classified into three different categories like slotted, Parasitic/Stub, and Electromagnetic Bandgap (EBG) structure-based geometry. Besides, generation of notched band characteristics over UWB-MIMO antennas with notched reconfigurability has also been detailed, which will be helpful for readers to understand their switching mechanisms from one band to another band.