A compact, conformal, all-textile wearable antenna is proposed in this paper for the 2.45 GHz ISM (Industrial, Scientific and Medical) band. The integrated design consists of a monopole radiator backed by a 2 × 1 Electromagnetic Band Gap (EBG) array, resulting in a small form factor suitable for wristband applications. An EBG unit cell is optimized to work in the desired operating band, the results of which are further explored to achieve bandwidth maximization via floating EBG ground. A monopole radiator is made to work in association with the EBG layer to produce the resonance in the ISM band with plausible radiation characteristics. The fabricated design is tested for free space performance analysis and subjected to human body loading. The proposed antenna design achieves bandwidth of 2.39 GHz to 2.54 GHz with a compact footprint of 35.4 × 82.4 mm². The experimental investigations reveal that the reported design adequately retains its performance while operating in close proximity to human beings. The presented Specific Absorption Rate (SAR) analysis reveals 0.297 W/kg calculated at 0.5 W input power, which certifies that the proposed antenna is safe for use in wearable devices.

A novel and miniaturized semi-elliptical 20-bit fully passive chipless RFID sensor tag is proposed in this article. The realized sensor tag is made up of semi-elliptical shaped open-end slots within the compact size of 25 mm × 17 mm. The multi-substrate analysis of the proposed tag is examined using non-flexible and flexible materials. The articulated tag configuration is capable of monitoring moisture levels when the largest resonator is covered by a heat-resistant sheet of Kapton HN (DuPontTM). The proposed tag functions in the operational frequency band of 4.1 GHz–16 GHz and possesses the overall bit density of 4.70 bit/cm². The structure is composed of a thin passive substrate layer topped with an active layer of conductive path and is considered as a potential candidate for low-cost identification of the tagged objects. In addition to that, its moisture sensing property and flexible nature make it a reliable smart sensor for conformal applications.

In this paper, a compact, miniaturized, and flexible chipless RFID tag is proposed. The realized tag possesses the encoding capacity of 9-bits. The tag is made up of slotted octagonal resonant elements that are placed in a nested loop manner to analyze the electromagnetic performance of the tag. The proposed tag is investigated for three different substrates from non-flexible to flexible, i.e. Taconic TLX-0, PET and Rogers RT/duroid®/5880. With Taconic TLX-0 as a substrate, the tag operates in the RF band of 4.3 GHz - 12 GHz while PET-based tag covers RF band of 4.7 GHz - 13.7 GHz and Rogers RT/duroid®/5880 based tag operates in the squeezed frequency spectrum of 4 GHz - 12.3 GHz. The presented tag is suitable to be deployed as an enabler of the Internet of Things.