This study presents a two element multiple‐input‐multiple‐output (MIMO) reconfigurable antenna for ultra wideband (UWB) applications. Each individual antenna is composed of a modified square radiating patch. The array can be reconfigured by either placing antenna elements orthogonally for corner installation or by placing them back‐to‐back for compact three‐dimensional (3D) modules. The design is fabricated on FR4 substrate having dimensions 40 mm × 37.5 mm × 1.5 mm. Port isolation greater than 20 dB in the complete band is achieved by introducing an efficient decoupling structure in the ground plane. Performance parameters such as S‐parameters, radiation patterns, envelope correlation coefficient, total active reflection coefficient and channel capacity loss indicate that the proposed MIMO design is a suitable candidate for high data rate UWB applications. The proposed solution is suitable for non‐planar designs around wall corners or for compact 3D structures where side‐by‐side placement is not practical due to size constraints.

This paper proposes a low-cost, compact, flexible passive chipless RFID tag that has been designed and analyzed. The tag is a bowtie-shaped resonator based structure with 36 slots; where each patch is loaded with 18 slots. The tag is set in a way that each slot in a patch corresponds to a metal gap in the other patch. Hence there is no mutual interference, and high data capacity of 36 bits is achieved in such compact size. Each slot corresponds to a resonance frequency in the RCS curve, and each resonance corresponds to a bit. The tag has been realized for Taconic TLX-0, PET, and Kapton ® HN (DuPont TM ) substrates with copper, aluminum, and silver nanoparticlebased ink (Cabot CCI-300) as conducting materials. The tag exhibits flexibility and well optimized while remaining in a compact size. The proposed tag yields 36 bits in a tag dimension of 24.5  25.5 mm 2 . These 36 bits can tag 2 36 number of objects/items. The ultimate high capacity, compact size, flexible passive chipless RFID tag can be arrayed in various industrial and IoT-based applications.

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