On-Body Antenna With Ultrawide Operation Band and Dynamically Broad Notch Band for IoT Applications

This article presents an on-body antenna characterized by low structural complexity, low spatial power density, and high robustness. This antenna features unique dual-wideband capability, offering ultrawideband operating frequency bands along with dynamic wideband notch tunability. This design aims to support simultaneous multiuser IoT operation while intelligently mitigating in-band interference from unwanted users. This achievement is realized through a novel approach using a reconfigurable quasi-spoof surface plasmon polaritons waveguide filter as the feedline for a substrate-integrated waveguide (SIW) antenna, allowing tuning of band-notched characteristics via varactor diodes on the SSPP element. Enhanced bandwidth performance is achieved by etching gradient rectangular slots on the open-ended SIW and implementing a transition from grounded coplanar waveguide to SIW with tapered coupling slots. Conductive fibers effectively bond the flexible foam substrate with a conductive thin copper film, forming the prototype. The prototype antenna operates across 9.4 to 29 GHz with an average gain of 9.0 dBi and features a dynamically tunable 2 GHz rejection bandwidth within the 14 to 26 GHz range, adjusted via variable capacitors in loaded varactors. The antenna maintains consistent performance under deformation and exhibits reliable wireless signal transmission in experiments.