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This study brings out the design, fabrication and performance evaluation of a compact, dual band antenna on paper substrate. The two bands of operations are 2.18 to 2.50 and 5.22 to 5.72 GHz. These bands are used by the wireless sensor networks (WSNs) and radio frequency identification systems (RFID). The antenna becomes useful for the WSN nodes and RFID systems at these frequencies. The overall size of the antenna is 40 mm× 20 mm× 0.6 mm, which makes it a compact one. Antenna was tested for the effect of bending by placing it over curvilinear surfaces. The bending was done in horizontal (X) and vertical (Y) axes. These examinations will help to understand the effect of wind loading and other packaging related bending on antenna performance. The main features of this antenna are stability in performance under bent conditions, simple configuration and low cost of fabrication. A thin polyethylene layer has been used to laminate the antenna for permanence. The effect of lamination has also been explained in the course of the study. [ABSTRACT FROM AUTHOR]

The work presented is an assay done on the effects of wearable antenna when placed in proximity to the human body. Cloth fabric is used as a substrate to design a planar antenna. Measurement results of the fabricated patch at free space and close to the human body are also presented here. The S11 of the designed antenna when placed close to the body tissue is almost -30 dB and the gain is close to 4 dB. A rectangular three layered human body model is used to evaluate the extent of the effect that the human body has on the parameters that define an antenna like its gain, directivity, etc. [ABSTRACT FROM AUTHOR]

A novel compact folded antenna for 4G and 5G application in handheld devices such as mobile phones is proposed in this paper. The radiator comprises of meandered monopole, dual L-Shaped monopole, square radiator, asymmetric U-Shaped monopole, Closed Loop resonator, F-Shaped stub for providing the desired operating bands. The size reduction is achieved using folding technique. The antenna can be easily folded and integrated at the top right corner within the metal casing of the devices. Folded structure with the foot print of 50 × 6 mm2 covers multiband operation such as LTE700 / GSM850 / 900 / LTE 2300 / WLAN 2400 / LTE 2500 / Wi-MAX 3500 / Wi-Fi 5200/5800 MHz corresponds to 2G/3G/4G/5G services. To provide high data rate and throughput, MIMO concept is exploited with the folded radiators at the top left and right corners of the printed circuit board. The realized gain and radiation efficiency of the proposed antenna are 2.45/4.12/4.54/5.03/6.58 dBi and 82/85/87/89/90% respectively at the design frequencies 0.7/2.3/2.5/3.5/5.8 GHz. The SAR values of the folded antenna is computed and found to be less than 1.6 W/Kg. [ABSTRACT FROM AUTHOR]

A low profile frequency reconfigurable antenna for WBAN applications is reported. The presented antenna design utilizes switching characteristics of PIN diode to achieve frequency reconfigurability. The dimension of the proposed antenna is 0.136 λ 0 × 0.131 λ 0 × 0.001 λ 0. The modified loop-shaped resonator, U shaped stub, and Mirrored F shaped strip provides an independent resonance for three distinct frequency bands. The application bands selected are 1.575 GHz (Global Positioning System), 2.45 GHz (Industrial, Scientific and Medical bands), and 5.2 GHz (Industrial, Scientific and Medical bands/Wireless Fidelity). The percentage bandwidth obtained is 3.17/1.83/2.69% at the said operating frequencies respectively. The simulated gain and total efficiencies are 3.26/3.47/4.04 dBi and 82/85/88% respectively. The directional radiation pattern obtained is highly suitable for off-body communication. The SAR is simulated to validate its suitability for wearable applications. The performance metrics of the fabricated prototype antenna is validated using Measurements. [ABSTRACT FROM AUTHOR]

A low profile flexible linear to circular polarizer made of paper substrate is proposed in this paper. The polarizer is constructed from frequency selective surface (FSS) comprising of crossed dipole unit cell elements. The polarizer converts the linearly polarized incident electromagnetic wave to circular polarized wave at 7.0 GHz. The polarizer provides the advantage of use in conformal system, which is substantiated using bending analysis. The proposed reflective polarizer provides a 3 dB axial ratio bandwidth of 13% at the center frequency of 7.0 GHz. In addition, the proposed flexible polarizer provides stable response for angular incidences up to 30°. Prototype of the flexible FSS polarizer is fabricated and its simulation results are validated with experimental measurements. [ABSTRACT FROM AUTHOR]

This article presents the design of a three‐port diversity antenna capable of producing three‐directional radiation pattern for vehicular communications. The proposed antenna consists of three uncorrelated Vivaldi antennas that are interconnected and developed on a single printed circuit board. Unlike many other antennas reported for the vehicular environment, the proposed antenna offers ultra‐wideband characteristics with end‐fire radiation pattern leading to high realized antenna gain. The integrated antenna has a footprint of 65 × 40 × 1.6 mm3 and offers 6 GHz impedance bandwidth extending from 5 to 11 GHz. The port‐to‐port isolation is greater than 20 dB within the operating bandwidth. Furthermore, the diversity performance of the proposed three‐port antenna system is evaluated and presented. The calculated envelope correlation coefficient, diversity gain, and mean effective gain are well above the minimum requirement. The prototype antenna is fabricated and the experimental results are presented. [ABSTRACT FROM AUTHOR]

This paper presents a twelve-port ultra-wideband multiple-input-multiple-output (MIMO)/diversity antenna integrated with GSM and Bluetooth bands. The twelve-port antenna is constructed by arranging four elements in the horizontal plane and eight elements in the vertical plane. The antenna element, which is created using a simple rectangular monopole, exhibits a frequency range of 3.1 to 12 GHz. The additional Bluetooth and GSM bands are achieved by introducing stubs into the ground plane. The size of the MIMO antenna is 100 × 100 mm2. The antenna offers polarization diversity, with vertical and horizontal polarization in each plane. The diversity antenna has a bandwidth of 1.7–1.9 GHz, 2.35–2.55 GHz, and 3–12 GHz, the radiation efficiency of 90%, and peak gain of 2.19 dBi. The proposed antenna offers an envelope correlation coefficient of < 0.12, apparent diversity gain of > 9.9 dB, effective diversity gain of > 8.9 dB, mean effective gain of < 1 dB, and channel capacity loss of < 0.35 bits/s/Hz. Also, the MIMO antenna is tested for housing effects in order to determine its suitability for automotive applications. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

An optically transparent circularly polarized (CP) radio frequency identification (RFID) antenna is presented in this paper. The RFID antenna consists of a coplanar‐fed waveguide inverted L‐shaped monopole with a dual feeding structure. The CP wave with a bidirectional radiation pattern is obtained by feeding the radiator at both ends. The transparency of the antenna is obtained by using fluorine tin oxide (FTO) coated soda‐lime glass substrate. The proposed antenna operates at a Universal RFID frequency (800–1100 MHz) with circular polarization. The antenna has an impedance bandwidth of 300 MHz and an overlapped 3‐dB axial ratio (AR) bandwidth of 110 MHz (860–970 MHz, 12% centered at 915 MHz). It has a peak realized gain of 1.4 dBic. The antenna with the size of 100 × 100 mm2 is designed for ultrahigh‐frequency RFID reader applications. [ABSTRACT FROM AUTHOR]

Abstract In this paper, flexible, low profile and robust planar monopole antennas are designed and analyzed for its performance over conformal surfaces, intended for Ultra-Wideband (UWB) and Body Centric Wireless Communications (BCWC). By the aid of alike shape (modified rectangular shaped) radiator and truncated ground plane, two compact microstrip fed antennas are designed and fabricated on flexible substrates – Polyamide and Teslin (environmentally friendly, flexible and green-electronics). The proposed polyamide antenna with a size of 50 mm × 40 mm × 0.8 mm, radiates over frequency range from 1.8 to 13.3 GHz and teslin antenna with a dimension of 50 mm × 40 mm × 0.712 mm, covers the frequency range from 1.4 to 13.4 GHz. To validate the designed prototypes, the antennas are fabricated and the impact performance are analyzed, while flexing the antenna from its nominal straight arrangement (bending through its length, width, different bending radius and angles). Further, time domain analysis is carried out in free space and in various bent scenarios with pulse excitation to validate the antennas for UWB applications. The transmission coefficient characteristics (S21) and group delay for various bending conditions are measured and the fidelity factor for all the scenarios are greater than 0.82, which make the antennas good candidate for UWB-BCWC. [ABSTRACT FROM AUTHOR]

The demand for vehicular antennas increases in tandem with the need for multiple features in automobiles. The development of optically transparent antenna (OTA) has made it possible to deploy antennas on delicate surfaces such as glass. Earlier studies on OTA demonstrated its viability using materials such as transparent conducting oxides (TCO) and conductive polymers. A tri-band OTA is proposed in this paper for vehicular applications. The antenna operates at 1.8 GHz, 2.4 GHz and 3.39-12 GHz bands, covering automotive/wireless applications such as GSM, Bluetooth, Wi-Fi, vehicular communication and electronic toll collection. The proposed OTA is developed on soda lime glass, and the material TCO is used for the radiator and the ground plane. The antenna prototype is tested on windshield and in an anechoic chamber, the gain and efficiency are found to be greater than 1 dBi and 80%, respectively. Furthermore, a machine learning technique for vehicle classification is proposed, which could help in electronic toll collection, automatic vehicle identifier, and parking management applications. The presented algorithm achieves 80% classification accuracy with a minimum window size., (© 2023. Springer Nature Limited.)

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.