A miniaturized-slotted planar MIMO antenna with switchable configuration for dual-/triple-band notches

This paper outlines the design and validation of a four-port compact Multi-Input Multi-Output (MIMO) antenna engineered to provide reconfigurable band notches within the ultra-wideband spectrum. The antenna features a circular monopole engraved with split ring slots along its radiating section, while a U-shaped slot is etched onto the feed line to facilitate band notches at specific frequencies—4.3 GHz (corresponding to INSAT), 6.8 GHz (aligned with Wi-Fi-6E), and 8.3 GHz (pertaining to X-band satellite). To ensure proper isolation, the MIMO elements are arranged orthogonally, and a decoupling periodic structure is strategically interposed between these elements to enhance isolation further. The incorporation of a PIN diode within the U-shaped slot introduces reconfigurability into the band notching mechanism. The MIMO antenna operates in two distinct modes depending upon the state of the PIN diode, either activated (ON) or deactivated (OFF). In the former mode, the antenna offers switchable band notches across three frequencies, while in the latter mode, it offers band notches at two specific frequencies. The validity of the antenna’s performance is validated through real-time fabrication and measurement. Both simulated and measured results exhibit a notable correlation. The antenna stands as an appropriate candidate for future cognitive radio applications.