Electromagnetic Bandgap Surface Research Articles

Improved wearable, breathable, triple‐band electromagnetic bandgap‐loaded fractal antenna for wireless body area network applications

AbstractA compact triple‐band porous electromagnetic bandgap structure‐loaded coplanar‐waveguide‐fed wearable antenna is introduced for applications of wireless body area networks. The porous structure is aimed to create a stopband or bandgap in the electromagnetic spectrum and increase breathability. The holes in the bottom electromagnetic bandgap surface increase the inductance, which in turn increases the bandwidth. The final design resonates at three bands with impedance bandwidths of 264 MHz, 100 MHz, and 153 MHz and maximum gains of 2.18 dBi, 6.75 dBi, and 9.50 dBi at 2.45 GHz, 3.5 GHz, and 5.5 GHz, respectively. In addition, measurements indicate that the proposed design can be deformed up to certain curvature and withstand human tissue loading. Moreover, the specific absorption rate remains within safe levels for humans. Therefore, the proposed antenna can suitably operate in the industrial, scientific, and medical, Bluetooth, Wi‐Fi, and WiMAX bands for potential application to wireless body area networks.

Electromagnetic Band Gap Based Via-less Jeans Patch Antenna for 5.5GHz WiMAX Application

Wearable electronics have gained opportunities in recent years, and the last decade has been evidence of this growth in Wireless Body Area Networks (WBAN). They meet the criteria for personalizing healthcare, communication, patient monitoring, tracking, and rescue operations. The main challenge for the WBAN is to handle the radiator's coupling with the human body. An artificially generated Electromagnetic Band Gap (EBG) structure was designed and used in this work to improve the performance of a microstrip patch antenna. A jeans-based microstrip patch antenna with an EBG surface demonstrated to enhance the performance for 5.5 GHz WiMAX application. The use of an EBG surface increases return loss by 20%, with a reasonable bandwidth of 0.528 GHz (5.271 GHz to 5.749 GHz) at the resonance frequency of 5.5 GHz. The EBG surface improved the Voltage Standing Wave Ratio (VSWR) by 60%. A three-layered human body tissue model is also used for on-body measurements to determine the performance of an EBG-based antenna. The presence of human tissues generally reduces performance and shifts the resonance, but the shifting in this work with the simplified EBG structure and adequate gain and VSWR is only 2.6 percent.

Performance Analysis of Wearable Dual-Band Patch Antenna Based on EBG and SRR Surfaces.

This paper presents the performance comparison of a dual-band conventional antenna with a split-ring resonator (SRR)- and electromagnetic bandgap (EBG)-based dual-band design operating at 2.4 GHz and 5.4 GHz. The compactness and dual-frequency operation in the legacy Wi-Fi range of this design make it highly favorable for wearable sensor network-based Internet of Things (IoT) applications. Considering the current need for wearable antennas, wash cotton (with a relative permittivity of 1.51) is used as a substrate material for both conventional and metamaterial-based antennas. The radiation characteristics of the conventional antenna are compared with the EBG and SRR ground planes-based antennas in terms of return loss, gain, and efficiency. It is found that the SRR-based antenna is more efficient in terms of gain and surface wave suppression as well as more compact in comparison with its two counterparts. The compared results are found to be based on two distinct frequency ranges, namely, 2.4 GHz and 5.4 GHz. The suggested SRR-based antenna exhibits improved performance at 5.4 GHz, with gains of 7.39 dbi, bandwidths of 374 MHz, total efficiencies of 64.7%, and HPBWs of 43.2 degrees. The measurements made in bent condition are 6.22 db, 313 MHz, 52.45%, and 22.3 degrees, respectively. The three considered antennas (conventional, EBG-based, and SRR-based) are designed with a compact size to be well-suited for biomedical sensors, and specific absorption rate (SAR) analysis is performed to ensure user safety. In addition, the performance of the proposed antenna under bending conditions is also considered to present a realistic approach for a practical antenna design.

Combined RIS and EBG Surfaces Inspired Meta-Wearable Textile MIMO Antenna Using Viscose-Wool Felt.

In this paper, we present a textile multiple-input–multiple-output (MIMO) antenna designed with a metamaterial inspired reactive impedance surface (RIS) and electromagnetic bandgap (EBG) using viscose-wool felt. Rectangular RIS was used as a reflector to improve the antenna gain and bandwidth to address well known crucial challenges—maintaining gain while reducing mutual coupling in MIMO antennas. The RIS unit cell was designed to achieve inductive impedance at the center frequency of 2.45 GHz with a reflection phase of 177.6°. The improved bandwidth of 170 MHz was achieved by using a square shaped RIS under a rectangular patch antenna, and this also helped to attain an additional gain of 1.29 dBi. When the antenna was implemented as MIMO, a split ring resonator backed by strip line type EBG was used to minimize the mutual coupling between the antenna elements. The EBG offered a sufficient band gap region from 2.37 GHz to 2.63 GHz. Prior to fabrication, bending analysis was carried out to validate the performance of the reflection coefficient (S11) and transmission coefficient (S21). The results of the analysis show that bending conditions have very little impact on antenna performance in terms of S-parameters. The effect of strip line supported SRR-based EBG was further analyzed with the fabricated prototype to clearly show the advantage of the designed EBG towards the mutual coupling reduction. The designed MIMO-RIS-EBG array-based antenna revealed an S21 reduction of −9.8 dB at 2.45 GHz frequency with overall S21 of <−40 dB. The results also indicated that the proposed SRR-EBG minimized the mutual coupling while keeping the mean effective gain (MEG) variations of <3 dB at the desired operating band. The specific absorption rate (SAR) analysis showed that the proposed design is not harmful to human body as the values are less than the regulated SAR. Overall, the findings in this study indicate the potential of the proposed MIMO antenna for microwave applications in a wearable format.

Designing of Unit EBG Cell Using Conductive Textile for Dual Band Operation

Background/Objectives: Flexible electronics have paved the way for Wireless Body Area Networks (WBAN). The main challenge in accommodating such applications is reducing the impact of radiation on the human body. The presence of body tissues may affect WBAN devices such as wearable sensors and wearable antennas, so reducing back radiations becomes an important task. Methodology: When a microstrip patch antenna is placed on a human body, the artificially formed Electromagnetic Band Gap (EBG) surface mimics the property of a Perfect Magnetic Conductor (PMC) rather than the conventional Perfect Electrical Conductor (PEC). Findings: In this work, the unique property of the EBG surface beneath the patch antenna creates a zero phase shift at the resonance, which improves the antenna’s performance and reduces back radiations as well. The proposed EBG surface structure is the simplest square-shaped structure with no conductor connections Via patch (Via-less). Novelty: The EBG structure designed and presented in this paper has zero reflections for the dual-band of operations. The resonance frequency of 2.45GHz and 5.5 GHz has been designed for the absorption of 80% and 65% respectively. This level of absorption has not yet been reported in the literature. The newly formed EBG cell integrated with the patch antenna and its performance improvements has been shown. The analysis shows that the EBG enhances the return loss by 20.35 % and gain enhances by 16.44 %, on textile materials with the advantage of most simplex EBG cell construction. Keywords: EBG; PMC; PEC; Wearable Microstrip Patch Antenna; WBAN

In-band RCS reduction antennas using an EBG surface

AbstractThe paper has proposed a multilayer, polarization rotation featured, low radar cross-section (RCS) antenna using electromagnetic band-gap (EBG)-based frequency selective surface (FSS) at 8.25 GHz. Cross-shaped EBG unit cells offer zero reflection phase and −25 dB reflection magnitude at 8.25 GHz. The FSS layer consists of eight cross-shaped EBG unit cells sandwiched between two substrates to offer high absorptivity at the desired band. The circular patch antenna resonating at 8.25 GHz is placed on the top substrate having a lower dielectric constant. Four circular-shaped patches are etched at the four corners of the top layer and are coupled with two feed lines which are aligned 90° to each other at the bottom layer and interconnected diagonally to achieve polarization rotation. The proposed antenna offers a gain of 6.72 dB and an in-band RCS of −21.4 dBsm. Incident energy is backscattered into eight directions separated by angle ϕ = 45°. The proposed antenna has the RCS reduction band of 7.7–9.4 GHz. It offers normalized polarization rotation ratio more than 0.8 within the −40° to 40° angular region at the frequency band 8–8.5 GHz. The measured result using the fabricated prototype agrees well with the simulated one.

X-Band Multilayer Stacked Microstrip Antenna Using Novel Electromagnetic Band-Gap Structures

In this work, a multi-layered rectangular microstrip antenna, with an inset feeding technique, is designed. It consists of a 10 GHz resonating conventional microstrip patch and a novel 9 × 9 electromagnetic bandgap (EBG) array printed on a 0.5 mm thin FR-4 epoxy as superstrate; an air-spacer separated both. The top radiating patch is magnetically coupled with the bottom radiator such that it also radiates. The bottom dielectric layer’s other side is finished with the perfect ground for minimizing the back-lobe radiation. The dimensional parameters are optimized for both patch and the EBG surface in the Finite Element Method (FEM)-based EM solver ANSYS HFSS. The superimposition of the top EBG surface improves the gain without degrading the performance of the lower patch. This antenna has a −10 dB reflection bandwidth of 1.2 GHz with −30.57 dB minimum reflectivity at 9.9 GHz (better VSWR). The proposed prototype offers a gain of 9.45 dBi in both E and H planes. Finally, the device is fabricated using the conventional PCB technology. The performances of the device, like gain and radiation pattern, are measured in the anechoic chamber. It is found that the simulation and measured results are in near agreement. The physical dimensions of the proposed antenna are 55 mm × 55 mm × 17.67 mm.

A Novel Waveguide-Below-Cutoff Structure With an Extended Cutoff Frequency

In this letter, a novel waveguide-below-cutoff (WBC) structure with electromagnetic bandgap (EBG) surfaces is proposed to increase the cutoff frequency without sacrificing the waveguide size. To implement the proposed WBC structure, EBG arrays with various via patterns are fabricated and attached to the wide walls inside a normal rectangular waveguide. Transmission loss of the WBC structure is measured in terms of different EBG arrays, and it is confirmed that the cutoff frequency could be extended to higher frequencies accordingly.

Printed compact asymmetric dual L‐strip fed split‐ring shaped EBG‐based textile antenna for WBAN applications

AbstractThis letter presents a design of very compact asymmetric dual L‐strip fed split‐ring shaped electromagnetic bandgap (EBG)‐based textile antenna for wireless body area networks (WBAN) applications, operating at frequency 2.45 GHz. The antenna radiator is composed of 2 × 1 array of EBG cells printed on same side of the substrate with partial ground plane to form a compact EBG surface, excited with a 50 Ω inverted L‐strip feed line. The partial ground plane with EBG cells is used to miniaturize the proposed antenna of size 40 × 20 × 0.3 mm3. The proposed compact asymmetric dual L‐strip fed wearable antenna (DLSWA) with EBG structure is fabricated on denim (jeans) substrate having dielectric constant (ɛr) 1.7 and thickness of 0.3 mm. The design of proposed antenna is optimized for Industrial, Scientific, and Medical (ISM) band (2.4‐2.48 GHz)through various parametric variations with simulated impedance bandwidth (BW) of 12.2% (2.3‐2.6 GHz) for reflection coefficient |S11| ≤ −10 dB and also exhibits stable radiation patterns with simulated peak realized gain of almost 3.5 dBi in the entire operational frequency band. The performance of proposed wearable antenna on human body is also studied and observed low specific absorption rate (SAR) value of 0.6 W/kg over 10 g of human tissues. The proposed compact asymmetric DLSWA is designed, fabricated, and tested. The simulated results of designed antenna are verified and validated with measured results which show good agreement for all radiation characteristics of proposed antenna for WBAN applications.

High quality factor fractal inductor with complementary split-ring array inclusion

PurposeThis paper aims to present an efficient method to improve quality factor of printed fractal inductors based on electromagnetic band-gap (EBG) surface.Design/methodology/approachHilbert fractal inductor is designed and simulated using high-frequency structural simulator. To improve the quality factor, an EBG surface underneath the inductor is incorporated without any degradation in inductance value.FindingsThe proposed inductor and Q factor are measured based on well-known three-dimensional simulator, and the results are compared experimentally.Practical implicationsThe proposed method was able to significantly decrease the noise with increase in the speed of radio frequency and sensor-integrated circuit design.Originality/valueFractal inductor is designed and simulated with and without EBG surfaces. The measurement of printed circuit board prototypes demonstrates that the inclusion of split-ring array as EBG surface increases the quality factor by 90 per cent over standard fractal inductor of the same dimensions with a small degradation in inductance value and is capable of operating up to 2.4 GHz frequency range.

Conformal self‐balanced EBG integrated printed folded dipole antenna for wireless body area networks

A self-balanced electromagnetic bandgap (EBG) integrated, conformal printed T-shaped folded dipole antenna for wireless body area network (WBAN) is proposed in this study. The folded dipole antenna designed using polyester film and copper tape operates at 2.4 GHz industrial, scientific and medical radio bands. Integrating antenna with a two-element EBG reduces the frequency shift and back scattering of radiation into the body. The higher impedance bandwidth of the folded dipole plays a key role in maintaining resonance while the antenna is wrapped on a human arm. When the antenna is conformed on a human arm, EBG surface minimises the specific absorption rate (SAR), increases the gain and front-to-back ratio (FBR). Additionally, full-wave simulations and measurements were done to validate the proposed antenna design even when conformed to the human arm of people from different age groups. The FBR and gain of the antenna are improved by 75 and 61% and SAR has been reduced by 99% when it is integrated with EBG. The good impedance matching, high gain and FBR and reduced SAR make it a perfect candidate for WBAN.

A W-Band EBG-Backed Double-Rhomboid Bowtie-Slot On-Chip Antenna

A double-rhomboid bowtie-slot on-chip antenna aided by a back-to-back E-shaped electromagnetic bandgap (EBG) surface for gain enhancement at W-band is presented. The specific structure of both the antenna and the EBG surface is being reported for the first time in an on-chip implementation. The antenna is analyzed independently as well as backed by different electromagnetic bandgap reflective surfaces using standard 0.13 $\mu$ m BiCMOS process. The proposed EBG surface provides a measured gain enhancement of 2 and 8 dB when used as a frequency selective surface and as an artificial magnetic conductor, respectively. With an overall chip size of 1 $ {}\times {\text{1 mm}}^{2}$ , the on-chip antenna demonstrates a $-$ 6 dB impedance bandwidth from 75–100 GHz and an effective gain bandwidth from 80–90 GHz with a peak measured gain of $-$ 0.58 dBi at 84 GHz. The antenna has the smallest reported size and the highest gain in W-band with artificial magnetic conductor as reflective surface.

Design and comparative analysis of conventional and metamaterial‐based textile antennas for wearable applications

AbstractIn this paper, four different models of a 2.4 GHz flexible microstrip patch wearable antenna are designed and analyzed. The basic geometry of the radiating element of the antennas is a rectangular patch and is backed by conventional, mushroom‐type, slotted, and spiral electromagnetic band gap (EBG) ground planes. A 3‐mm‐thick wash cotton textile is used as a substrate material in the design of the antennas as well as EBG surfaces. An electro‐textile (Zelt) is used as a conductive material for the proposed antennas. The performance of these antennas is analyzed in terms of return loss, gain, bandwidth efficiency, and specific absorption rate (SAR) using Computer Simulation Technology Microwave Studio (CST MWS). The designed antennas are further investigated for on and off body conditions under normal and bent states. The experimental results show that the antennas radiate with an adequate gain (5.72‐7.3 dB), bandwidth (65.43‐103.1 MHz), and efficiency (55.51%‐74.04%), depending on the type of the ground plane used. The antenna backed by the mushroom‐type EBG gives the smallest value of SAR (1.79 W/kg &lt; 2 W/kg), which makes it a suitable candidate for body worn applications in the unlicensed industrial, scientific, and medical (ISM) band.

Wideband Linearly-Polarized and Circularly-Polarized Aperture-Coupled Magneto-Electric Dipole Antennas Fed by Microstrip Line With Electromagnetic Bandgap Surface

Wideband aperture-coupled magneto-electric (ME) dipole antennas fed by microstrip line are proposed in this paper. The aperture-coupled microstrip-line-fed method was utilized in the proposed configuration to replace the conventional Γ-shaped probe to excite the ME dipole antenna. Particularly, a printed mushroom-like electromagnetic bandgap (EBG) surface was mounted below the microstrip line to effectively eliminate the back radiation caused by the aperture on the ground plane. Two configurations of ME dipole antennas with linear polarization (LP) and circular polarization (CP) have been proposed for adequately studying the effect of the EBG surface. Both the simulation and measurement of the two prototypes had been carried out for verification. Based on the measured results, wide impedance bandwidth (SWR <; 2) of 54.9% and 58% can be obtained for both the proposed LP and CP ME dipole antennas, respectively. Besides, the performances of the stable broadside radiation pattern with the enhanced front-to-back ratio (FBR) can also be achieved for both configurations.

Combining FSS and EBG Surfaces for High-Efficiency Transmission and Low-Scattering Properties

In this communication, we propose a method to achieve high-efficiency transmission and wideband scattering reduction at two distinctive frequency bands by combining frequency-selective surface (FSS) and electromagnetic bandgap (EBG) surface. Such FSS-EBG surface is composed of two-layered metallic patterns. The bottom FSS layer works as a filter for allowing in-band signal to pass and reflecting out-of-band signal, while the top EBG layer adopts 0 and $\pi $ reflection phase cells with a chessboard distribution to reduce the backward scattering wave. As a proof-of-concept demonstration, the planar and cylindrical surfaces are, respectively, designed to verify such two functionalities. Our FSS-EBG surface can make the antenna signal transmit at S-band with small insertion loss and simultaneously provide wideband low-scattering property at X–Ku band, which is suitable to be used as the stealth antenna radome. In addition, the possibility of integrating polarization conversion function into the passing band is numerically demonstrated.

EBG-Backed Flexible Printed Yagi–Uda Antenna for On-Body Communication

An electromagnetic bandgap (EBG) structure backed, printed Yagi-Uda antenna for on-body communication is proposed in this communication. The proposed antenna is flexible, made of copper foil tape and polyester sheet. The antenna operates at 2.4-GHz industrial, scientific and medical radio band. A printed Yagi-Uda is used to achieve high gain, endfire radiation pattern, and decreased path loss. An EBG surface is also used to reduce the frequency detuning of the antenna and specific absorption rate (SAR) while increasing the antenna gain when placed on human body. Antenna gain has been increased by 60%, and SAR has been decreased from 8.55 to 0.07 W/kg when the antenna is backed with EBG.

Parametric Analysis of Wearable Vialess EBG Structures and Its Application for Low Profile Antennas

Electromagnetic Bandgap (EBG) structures are one class of metamaterial with attractive properties that unavailable in nature and widely used for improving the electromagnetic performance. Its In-phase reflection frequency band is indicated as operation frequency band, whose characteristic is closely related to the parameters of EBG structure, such as patch width (w), gap width (g), substrate height (h) and substrate permittivity (e). The presence of via within EBG structure is associated with design and fabrication complexities, which led the researchers to study uniplanar EBG. These structures require no via and can easily be fabricated and integrated with RF and microwaves alication. Therefore, an investigation study on the effect of the parameters of the vialess EBG surface and some design guidelines have been obtained. An example of an antenna integrated with EBG is also studied. The result indicates that the EBG ground plane significantly improves the work efficiency of the antenna in a particular frequency band.

Design and SAR Analysis of Wearable Antenna on Various Parts of Human Body, Using Conventional and Artificial Ground Planes

This paper presents design and specific absorption rate analysis of a 2.4 GHz wearable patch antenna on a conventional and electromagnetic bandgap (EBG) ground planes, under normal and bent conditions. Wearable materials are used in the design of the antenna and EBG surfaces. A woven fabric (Zelt) is used as a conductive material and a 3 mm thicker Wash Cotton is used as a substrate. The dielectric constant and tangent loss of the substrate are 1.51 and 0.02 respectively. The volume of the proposed antenna is 113×96.4×3 mm3. The metamaterial surface is used as a high impedance surface which shields the body from the hazards of electromagnetic radiations to reduce the Specific Absorption Rate (SAR). For on-body analysis a three layer model (containing skin, fats and muscles) of human arm is used. Antenna employing the EBG ground plane gives safe value of SAR (i.e. 1.77W/kg 2W/kg). The efficiency of the EBG based antenna is improved from 52 to 74%, relative to the conventional counterpart. The proposed antenna can be used in wearable electronics and smart clothing.

Gain Enhancement and RCS Reduction for Patch Antenna by Using Polarization-Dependent EBG Surface

A novel antenna design is proposed to enhance the gain and reduce the radar cross section (RCS) of a patch antenna by using metamaterial surface. A polarization-dependent metamaterial surface composed of blocks of slotted electromagnetic bandgap (EBG) structures are adopted in this letter. The layout pattern of the slotted EBG elements is designed to enhance the gain of the antenna. Chessboard configuration is further equipped for scattering cancellation. The induced currents on the EBG are studied, resulting in the mechanism of the gain enhancement by the EBGs clearly explained for the first time. This enables the strategy of designing a high-gain and low-RCS antenna by using EBGs. Full-wave simulations validate that high gain in the operating frequency band and low-RCS in a broad frequency band for normal incidence are achieved by the proposed antenna.

Experimental Study of Adulteration Detection in Fish Oil Using Novel PDMS Cavity Bonded EBG Inspired Patch Sensor

In this paper, a high impedance surface electromagnetic bandgap inspired resonator patch, bonded with a polydimethylsiloxane (PDMS) cavity was implemented as a sensor device for detecting adulteration in a fish oil dietary supplement. The fabricated sensor on a Neltec substrate of relative permittivity ( $\varepsilon _{r}= 3.2$ ) and dissipation factor (tan $\delta = 0.007$ ) has a unique pattern of electromagnetic bandgap unit cells, and offers TM01, TM11, and TM21 transverse magnetic modes for dielectric spectroscopy of the sample. The measured reflection coefficient at 2.592 GHz of the air-filled PDMS cavity bonded to the patch sensor under TM01 mode was used for calibrating the sensor subjected to 10%, 20%, 30%, 40%, and 50% adulteration in the fish oil. With olive oil as an adulteration ingredient inside fish oil, a maximum shift of 70 MHz was observed in the sensor frequency response for 50% adulteration level. A linearity of more than 91% was achieved in the response of the developed sensor.