The design of a silicone rubber-based wristband wearable antenna exploiting pattern diversity is presented in this paper. The wristband diversity antenna consists of four identical antenna elements with an inter-element spacing of 0.68λ0, where λ0 is the lower cut-off wavelength. A modified trapezoidal-shaped radiator with a rectangular ground structure is used to achieve ultra-wide bandwidth. The proposed multiple-input-multiple-output (MIMO)/diversity antenna covers a frequency range of 2.75–12 GHz. The antenna element offers a radiation efficiency of 89.3% and a gain of 3.41 dBi. The size of the wristband diversity antenna is 1.1λ0 × 18.4λ0 × 0.18λ0. The diversity performance characteristics of the prototype antenna are examined, with the envelope correlation coefficient (ECC) < 0.18, apparent diversity gain (ADG) > 9.5, effective diversity gain (EDG) > 9.5, mean effective gain (MEG) < 1 dB, total active reflection coefficient (TARC) < − 10 dB, and channel capacity loss (CCL) < 0.1  bits/s/Hz over the entire operating band. The specific absorption rate (SAR) of the proposed wristband antenna is analyzed to determine its radiation exposure on the human body, and the results show that the values are less than 0.02 W/kg.

A conformal four-port multiple-input-multiple-output (MIMO) antenna operating at 2.4 GHz and ultrawideband (UWB) is presented for wearable applications. The unit element of the MIMO antenna is a simple rectangular monopole with an impedance bandwidth of 8.9 GHz (3.1–12 GHz). In the monopole radiator, stubs are introduced to achieve 2.4 GHz resonance. Also, a defect is introduced in the ground plane to reduce backside radiation. The efficiency of the proposed antenna is greater than 95%, and its peak gain is 3.1 dBi. The MIMO antenna has an isolation of >20 dB, and the estimated specific absorption rate (SAR) values for 1 gm of tissue are below 1.6 W/Kg. The size of the four-port MIMO antenna is 1.38λ0 × 0.08λ0 × 0.014λ0.

This paper presents the design and development of a quad-port smart textile antenna for bio-healthcare applications. The antenna is designed to operate in the ultra-wideband (UWB) spectrum (3.1–12 GHz) with an impedance bandwidth of 8.9 GHz. The size of the unit cell and multiple-input multiple-output (MIMO) antenna are 0.25λ0 × 0.2λ0 × 0.015λ0 and 0.52λ0 × 0.52λ0 × 0.015λ0, respectively. The antenna has a maximum efficiency of 93% and a peak gain of 4.62 dBi. The investigation of diversity metrics is performed and the results obtained are found to be ECC < 0.08 and DG < 9.99 dB. The computed CCL and TARC values are <0.13 bits/s/Hz and <−12 dB, respectively. The SAR analysis of the antenna shows a value of 0.471 Watt/Kg at 4 GHz, 0.39 Watt/Kg at 7 GHz, and 0.22 Watt/Kg at 10 GHz.

No abstract

This paper presents the design of a quad-port orthogonal Ultra-Wideband (UWB) monopole antenna backed with an EBG structure. The EBG structure provides band stop / band reject characteristics in the entire UWB range. The overall dimension of the diversity antenna is 70 × 70 × 1〖 mm〗^3 (0.68λ_0× 0.68λ_0×〖0.01λ〗_0), where λ_0 corresponds to the lowest resonating frequency. The proposed monopole antenna offers good impedance bandwidth of 8.67 GHz (2.93-11.6 GHz). The estimated diversity characterization metrics observed over the obtained frequency range are Envelope Correlation Coefficient (ECC) < 0.11, Mean Effective Gain (MEG) < 1 dB, Effective Diversity Gain (EDG) < 9.88 dB, Apparent Diversity Gain (ADG) < 9.99 dB, Channel Capacity Loss (CCL) < 0.19 bits/s/Hz, and Total Active Reflection Coefficient (TARC) < -20.95 dB. Also, SAR analysis is realized for the antenna in seven different tissues of the body (forehead, forearm, upper arm, chest, abdomen, thigh and lower leg) to check radiation exposure towards the human body.