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In this research paper, the authors propose a unique broad-band circularly polarised antenna design with a sequentially rotated feed network intended for applications in the WiMAX IEEE 802.16, C-band, and ITU-R F386.9 bands. A sequential feeding approach utilising transmission lines with varying impedance properties and lengths has been utilised to properly stimulate the amplitude and phase distribution of each radiation element. To facilitate the rotation of the surface current distribution on the ground plane and further improve impedance matching, four L-shaped slits have been inserted into each corner of the ground plane along with a pair of mirrored slits of identical geometry within the antenna ground plane. The individual antenna element achieves an impedance bandwidth between 5–6.8 GHz and a 3 dB axial ratio bandwidth from 5.1–6.6 GHz. To additionally advance the radiation performance, the elements are configured into a 2 × 2 antenna and are interconnected utilising a sequentially rotated feeding network to attain broader axial ratio and impedance bandwidths. A key benefit of the implemented feed network is the minimisation of coupling effects between elements. To significantly increase the performance metrics of the antenna with limited increase to its physical size, electromagnetic band gap structures were incorporated as a one-dimensional lattice between the radiating elements. For the resulting antenna, an axial ratio bandwidth from 4.19 to 6.8 GHz (48%) and an impedance bandwidth spanning 2.9 to 9.8 GHz (102%) are achieved. The peak gain of the antenna is 11.2 dBic. [ABSTRACT FROM AUTHOR]

In the modern era of wireless communications, there is an ever increasing demand for compact antennas. The antennas that can operate across multiple frequency bands while effectively rejecting potential interfering signals. This need arises from the rapidly growing number of wireless systems and applications coexisting within the limited available spectrum. In this paper, elliptical monopole planar antenna with penta band notched characteristics is designed and fabricated for 5G/6G wireless system. The proposed antenna design incorporates two elliptical split ring resonators on the radiation patch to enable band rejection from 3.7 to 4.2 GHz for C band satellite communication along with 5.15–5.35 GHz for the lower WLAN band. A special metamaterial structure consisting of a two via double slot type EBG creates dual notches at 4.5–4.7 GHz for INSAT and 5.725–5.825 GHz for the upper band of WLAN. Additionally, In the vicinity of the feed line, a step impedance resonator suppresses the 7.95–8.55 GHz ITU band. This multi band notched characteristic makes the antenna suitable for applications requiring concurrent operation across multiple bands while mitigating interference from other co existing wireless services.The antenna is made with FR4 substrate and of a compact size of 38 × 38 × 0.8 mm3, making it suitable for integration into modern portable and wireless devices. [ABSTRACT FROM AUTHOR]

Recent advancements in wireless technology have prompted the development of wearable antennas, particularly for Wireless Body Area Networks (WBANs) used in sports, military activities, healthcare, and identification systems. Unlike traditional antennas, wearable antennas operate very close to the curved human body. Consequently, their performance metrics such as reflection coefficient, bandwidth, radiation characteristics, efficiency, gain, directivity, and Specific Absorption Rate (SAR) can be significantly affected by interactions with human body tissues. To address these challenges, periodic structures are integrated into wearable antenna designs to mitigate the effects of coupling and absorption by the human body. To date, a limited number of works have surveyed, compared, and categorized the proposed wearable antenna designs integrated with periodic structure based on their operating frequency bands and their interactions with the human body. To this end, this paper contributes to the literature by detailing the selection of materials, highlighting the limitations of wearable antennas, characterizing the periodic structures, elaborate on dielectric properties data of human body models, discussing the influence of periodic structures on antenna performance and their significance in isolating them from the human body. Furthermore, this study provides an in-depth review of 81 papers evaluating the performance of antennas integrated with periodic structures, both in free space and on the human body, across single-band, dual-band, and triple-band designs. The selected papers were chosen based on their publication in reputable journals, the quality of their research, and the comprehensiveness of their data analysis. In addition, it provides a summary of several common flexible materials used in wearable antennas with their electrical properties as well as the dielectric properties of the human body for different frequencies. Moreover, it discusses the challenges and considerations involved in designing appropriate wearable antennas.

The paper presents an UWB antenna for on-body application with advancements in EBG backed reflector incorporating the compatibility and flexibility in structure. The ultra-wideband (UWB) frequency range supported by the designed antenna is between 2.78 GHz and 18 GHz. The antenna is designed with jeans textile substrate for the compatibility in on-body applications, which has appealing qualities such as flexibility and low dielectric properties, while the antenna radiator patch and ground plane are made of copper. The designed antenna is applicable on human body, meticulously designed EBG surface that could minimize antenna frequency detuning, with specific absorption rate (SAR). This allows for a great deal of flexibility in terms of the antenna design, allowing it to realize a high gain, enhanced bandwidth and directional radiation pattern. The antenna gain is increased by 99.8 % once EBG is applied and the SAR is decreased from 22.03 W/kg to 0.104 W/kg. [ABSTRACT FROM AUTHOR]

Recently, groove gap waveguides (GGWs) have shown significant potential in power handling and bandwidth enhancement compared to conventional waveguides. In this research work, we designed and developed an innovative mushroom-unit-cell-based groove gap waveguide (MGGW) that has shown improved bandwidth compared to conventional GGW structures. The dispersion characteristics of the MGGW were analyzed through the eigenmode solver feature of Microwave Studio CST, which showed that the bandwidth was improved by 8% compared to conventional unit cells in the microwave spectrum. To validate our proposed method for the physical dimensions of unit cell structures, we developed an MGGW structure for the S band, which shows similar trends aligning with the simulation results. The measurement results are promising as a reflection coefficient of less than −20 dB was achieved over the entire band for the WR284 Electronic Industries Alliance (EIA) standard waveguide adapter. The proposed MGGW structure with improved bandwidth will open new doors for researchers to develop ultra-wide bandwidth microwave applications, i.e., filters, transmission lines, resonators, attenuators, etc. [ABSTRACT FROM AUTHOR]

A multiband microstrip antenna integrated with an electromagnetic bandgap (EBG) structure operating at WLAN and WiMAX frequencies is proposed for wearable applications. The antenna consists of a circular patch surrounded by the ground plane, separated by a ring slot. The size of the integrated antenna has been significantly reduced to 0.28 $\lambda $ λ ×0.28 $\lambda $ λ and thickness of 0.024 $\lambda $ λ. A single-layered planar groundless EBG structure has been designed to suppress the wideband of frequencies from 2.2 to 5.4 GHz. An equivalent circuit model is presented to explain the zero-degree reflection phase of the EBG. Integration of the antenna with the EBG structure and a simple resonator bestows operating bands at 2.45 and 5.2, 5.5 and 5.8 GHz with significantly low back radiation. The gain and directivity of the antenna have been increased to 5.41 dB and 6.2 dB, respectively. The Specific Absorption Rate (SAR) of the antenna has been reduced to 0.0859W/kg, which is significantly lower than the admissible SAR value recommended by the Federal Communications Commission (FCC). The antenna is fabricated on an FR4 substrate, and its measured radiation characteristics are well matched to the simulated one. [ABSTRACT FROM AUTHOR]

Summary A wearable dual‐band dual‐polarized fabric antenna is screen printed on a cotton polyester substrate to operate at the industrial scientific and medical band at 2.45 GHz and wireless local area network at 5.2 GHz. A rectangular slot with a pair of L‐shaped branches are used to excite dual bands. The rectangular slot is used to achieve lower band resonance at 2.45 GHz with linear polarization, and an L‐shaped branch with a stub is used to obtain the circular polarization at 5.2 GHz. A 3 × 3 electromagnetic bandgap (EBG) structure is enabled behind the antenna to minimize the back radiation and specific absorption rate (SAR). The antenna provides a measured impedance bandwidth (BW) of 25% from 2.1 to 2.7 GHz (600 MHz), and 18% from 4.5 to 5.7 GHz (1.2 GHz), respectively. The antenna also has a 3‐dB axial ratio BW of 15% from 4.6 to 5.35 GHz (750 MHz). The antenna exhibits a measured gain of 5.1 dB at 5.2 GHz and 6.4 dB at 2.45 GHz. The SAR is validated by using a CST (computer simulation technology) voxel human body model and found to be 0.0949 and 0.127 W/kg for 1 g tissue at 5.2 and 2.45 GHz, respectively. The dimension of the proposed EBG integrated antenna is (0.52 λ × 0.52 λ × 0.07 λ). The antenna and EBG structure are screen printed with silver conductive ink, which provides good conductivity, conformability, comfort, wearability, and being lightweight. [ABSTRACT FROM AUTHOR]

Summary: A dual‐band, wearable coplanar microstrip patch antenna (CPW) integrated with electromagnetic bandgap structure (EBG) to operate dual wireless bands at 2.48 GHz industrial, scientific, and medical band (ISM) and 5.2 GHz WLAN. The proposed textile wearable antenna and EBG structure are screen‐printed using silver conductive ink on the cotton polyester substrate (εr = 1.6) for flexible wearable applications. A 3 × 3 EBG array is realized by a concentric square patch surrounded by the annular square ring to reduce back radiation and increase the forward gain and front‐back ratio. The proposed EBG‐backed antenna, compared with the conventional CPW‐fed antenna, improves forward gain from 2.18 to 6.59 dB at 2.48 GHz and 3.5 to 7.03 dB at 5.2 GHz. Moreover, the EBG array is used to isolate the human body from the antenna and reduces the specific absorption rate (SAR). The antenna is performed with a human phantom tissue model, which exhibits a specific absorption rate of 0.12 W/kg, and 0.260 W/kg for 1 g tissue at 2.48 GHz and 5.2 GHz, respectively. [ABSTRACT FROM AUTHOR]

This work, presents a design of a nano-antenna based plasmonic materials at the frequency range from 192THz to 195THz for modern applications, including THz communication systems. The proposed antenna is constructed from the 3rd iteration of the Hilbert curve patch fed with a modified coplanar 50Ω port. The back layer of the antenna was covered with a partial ground plane defective with a metamaterial-based electromagnetic band gap (EBG) layer. The antenna shows high directivity up to 68dBi at 193.4THz with an excellent matching over the entire frequency band of interest. The proposed antenna is considered of gold conductive layer mounted on a silicon dioxide (SiO2) layer. The proposed EBG was designed as the second order of the Minkowski fractal geometry. The obtained results in terms of S11 were below -10dB for the frequency band of 3THz. These results were validated using numerical techniques based on CST MWS by invoking the time domain (TD) and frequency domain (FD) solvers. The results achieved from the considered techniques agreed very well with each other.

The primary objective of this paper is to conduct a comparative analysis of diverse Electromagnetic Band Gap (EBG) antennas in terms of their suitability for Wi-Fi applications operating at 5 GHz. Wi-Fi primarily operates within the 2.4 GHz and 5 GHz frequency bands, with the 5 GHz band offering higher data rates and reduced interference compared to the 2.4 GHz band. Furthermore, its larger number of available channels makes it an optimal choice for environments with high user density. The antennas in this study are designed with dimensions of 28.11x32.40x1.6 mm³ (length x width x height) using RT/Duroid 5880 substrate, which has a thickness of 1.6 mm and a relative permittivity (εr) of 2.2. The integration of Electromagnetic Band Gap structures in antenna designs has gained substantial attention due to their unique properties that enhance antenna performance characteristics. The paper presents sixteen distinct EBG antennas, all designed using CST software. These antennas incorporate various EBG shapes, such as Fork, L-shape, C-shape, Hash, and Z-shape, positioned on a rectangular patch and in the ground plane. The study's results reveal that the Hash EBG on the patch offers superior performance compared to other EBG types. As a result, the Hash EBG on the patch, alongside various Z-shaped EBGs on the ground plane, is assessed for different antenna performance parameters, including return loss, radiation patterns, and gain. Finally, a diagonal Z-shaped EBG antenna is designed, simulated, and tested. The antenna return loss at 5.2GHz is -48 dB The proposed antenna achieved a peak gain of 7.3 dB at 5.2GHz. The proposed antenna exhibits omnidirectional properties. The antenna shows an efficiency of 90% at the resonant frequency. The experimentally measured results of the designed diagonal EBG antenna have shown satisfactory agreement and are consistent with the simulated results. The findings of this research contribute to a better understanding of EBG antennas potential for Wi-Fi applications in the 5 GHz frequency band.

A novel and miniaturized design featuring a Co-directional Complementary Split Ring Resonator (CO-CSRR) loaded Tri-Quarter Circular (TQC) Extremely Wideband (EWB) Multiple-Input Multiple-Output (MIMO) antenna has been developed and simulated. This proposed antenna demonstrates high isolation and exhibits multiple notch characteristics. The configuration consists of two TQC patches positioned adjacent to each other with a common partial ground plane (PGP), achieving an Extremely Wideband (EWB) capability of 85.8 GHz. Additionally, two elliptical CO-CSRRs are etched on the TQC elements to introduce dual-notch characteristics in the X-band and Ku-band. The integration of two Electromagnetic Band Gap (EBG) structures on either side of the microstrip feedline facilitates the creation of notch frequency ranges at Q-band downlink and V-band. To enhance isolation, a slotted meandering strip is extruded to the PGP. This design primarily focuses on achieving EWB with a compact size and reduced complexity. The overall physical volume of the proposed design is $2.74~\lambda _{o} {\times } 4.83~\lambda _{o} {\times } 0.25~\lambda _{o}$ , achieved a maximum $|S_{11}|$ of 30.82 dB at a frequency of 17.58 GHz. The antenna’s performance has been thoroughly evaluated in terms of radiation pattern, isolation, Total Active Reflection Coefficient (TARC), Envelope Correlation Coefficient (ECC), Diversity Gain (DG), Gain, and Efficiency. Stable gain and Group Delay (GD) of less than 0.2 ns for the entire Extremely Wideband (EWB) range have been achieved, with lower gain observed at the notch bands.

Recently, groove gap waveguides (GGWs) have shown significant potential in power handling and bandwidth enhancement compared to conventional waveguides. In this research work, we designed and developed an innovative mushroom-unit-cell-based groove gap waveguide (MGGW) that has shown improved bandwidth compared to conventional GGW structures. The dispersion characteristics of the MGGW were analyzed through the eigenmode solver feature of Microwave Studio CST, which showed that the bandwidth was improved by 8% compared to conventional unit cells in the microwave spectrum. To validate our proposed method for the physical dimensions of unit cell structures, we developed an MGGW structure for the S band, which shows similar trends aligning with the simulation results. The measurement results are promising as a reflection coefficient of less than −20 dB was achieved over the entire band for the WR284 Electronic Industries Alliance (EIA) standard waveguide adapter. The proposed MGGW structure with improved bandwidth will open new doors for researchers to develop ultra-wide bandwidth microwave applications, i.e., filters, transmission lines, resonators, attenuators, etc.

A compact new ultra-wideband (UWB) antenna using planar metamaterial (MTM) structures is proposed. The antenna is designed with a double-side planar periodic cell structure. The proposed 3-D unit cell show an artificial negative electric permittivity medium (NEPM), exhibiting a wide electromagnetic bandgap (EBG) created by etching four L-shaped slots on the main square patch and crossed-shaped slots on the ground plane. The proposed antenna fabricated on a 1.52 mm low-cost Rogers RO4003C substrate, is compact, measuring 22.4 × 25.6 mm², with a relative permittivity of 3.38 and a loss tangent of 0.0027. It has a broad bandwidth covering 3.8 GHz to 17.7 GHz, relatively 129%. The average gain over the entire bandwidth is 5.44 dB, with a peak value of 8.55 dB at 15.5 GHz. Design and simulation were carried out using the finite integration technique (FIT)-based CST microwave studio. The measured return loss (S11) of the prototype was in good agreement with the simulated results. The proposed antenna shows satisfactory radiation efficiency, achieving between 80% and 93% over the whole band. The measured gain of the test antenna demonstrates favorable radiation characteristics and shows the stability of radiation patterns at low frequencies. A comparative study with the related literature reviews recently published highlights the compactness of our MTM antenna configuration, presenting a reduction factor between 43.13% and 56.25%. Due to its outstanding performance, the proposed design is positioned as a strong candidate for various UWB applications, and also can be used for satellite communications and radar applications. [ABSTRACT FROM AUTHOR]

This paper presents a wideband, thin-profile and enhanced-gain microstrip patch antenna improved by using a novel mushroom-like Electromagnetic Band Gap (EBG) structure and forming periodic Defected Ground Structures (DGS) on the ground plane. The proposed antenna operates between 9.56 and 14 GHz and has 4.44 GHz–10 dB impedance bandwidth. With A4, the gain of the reference antenna is increased by 64.4%, while a 38% bandwidth is also achieved. The parametric analyses carried out on the metallic part area of the novel EBG patch indicated that when the area of the used EBG patches are approximately three quarters or less of the conventional ones, greater gain values for the designed antenna are obtained. This relation between the EBG patches and the antenna gain can be pointed out as the novelty of the study. The results were analysed by the simulations carried out with CST Microwave Studio and were verified by measurements from manufactured prototypes. [ABSTRACT FROM AUTHOR]

The dense establishment of the Wi‐Fi devices creates an opportunity to map the surrounding environment using Wi‐Fi signals as sounding waveforms. Recently, the Channel State Information (CSI) measurement analysis from Wi‐Fi networks has been widely used for detecting and possibly tracking the presence of obstacles between a transmitter and a receiver. According to the IEEE 802.11bf Task Group, Wi‐Fi sensing will utilize a band between 5.925 and 7.125 GHz, making the CSI measurement finer‐grained with the additional large bandwidth. In this paper, a wideband compact antenna is designed targeting the 5.9–7.1 GHz band based on the slot‐loading technique. Later, a wideband multiple‐input multiple‐output (MIMO) antenna is designed using defected ground structures, protruded ground, and electromagnetic band gap structures for isolation improvement, and the measured isolation shows 30–45 dB between the elements in the operating frequency range. The envelope correlation coefficient is less than 0.001 with the diversity gain being nearly 10. The fabricated single antenna has a compactness of 0.3λ0 ${\lambda }_{0}$ in both dimensions (14 mm × $\times $ 14 mm), measured bandwidth of 1.55 GHz (5.95–7.5 GHz) with a peak gain of 2.2 dBi at 6.8 GHz, and 90% efficiency in the operating frequency range whereas the wideband MIMO antenna has a size of 14 mm × $\times $ 37 mm with 0.5λ0 ${\lambda }_{0}$ spacing between the elements. [ABSTRACT FROM AUTHOR]

In this paper, design and realisation of a low profile Archimedean spiral antenna is presented. The low profile Archimedean spiral antenna is printed on a substrate and backed by a reflector consisting of DGS. The DGS unit cell consists of a parallel combination of meander line inductors and inter-digital capacitors. This, DGS is one of the forms of electromagnetic band gap (EBG) structures providing electromagnetic band gap characteristics. It is used as a reflector with spiral antenna to achieve unidirectional radiation properties and a low profile of antenna. A modified version of uniplanar EBG cell is used as a DGS cell. This cell is used for configuration of the DGS ground plane. This ground plane is evaluated for its electrical characteristics and used as a reflector for the spiral antenna. Archimedean Spiral antenna is designed and simulated in the frequency band of 1-6GHz with DGS as a reflector. The antenna characteristics are studied for physical parameters of the antenna. These parameters are optimized for better electrical characteristics. The performance of the proposed antenna is also compared with conventional metallic (PEC) reflectors. Simulated results of an antenna are validated by measurement. Antenna height reduction of 60 % is achieved compared to conventional cavity-backed spiral antennas. [ABSTRACT FROM AUTHOR]

In this study, a novel pattern shaping technique is presented and applied to the uniquely designed multiple-input multiple-output (MIMO) radio altimeter antenna, acquiring area gain. Inspired by the behavior of the perfect electric conductor, the tendency to gather a diffuse pattern is exploited to create pattern shaping. A surface with a phase response of 0° at 3.824 GHz was designed to ensure that the target radio altimeter frequency of 4.3 GHz is in the immediate vicinity of the outer phase region, where the impedance is around 166.84 Ω, transforming the diffuse pattern of the top antenna into the target conical shape. Antenna reflection values are measured as −20.072 dB at 4.344 GHz (port 1) and −27.44 dB at 4.32 GHz (port 2), while there is 6 mm between the top antenna and its reflector. At 4.32 GHz, the envelope correlation coefficient is 0.0043, the diversity gain is 9.999, and the transmission value between the opposing ports is −29.08 dB, which indicates a low mutual coupling. A MIMO antenna with a measured gain of 10.1497 dBi for port 1 and 10.5617 dBi for port 2 conforming to the design criteria of the radio altimeter is achieved. [ABSTRACT FROM AUTHOR]

With the rapid advancements in wireless communication systems, the applications that have emerged recently such as the Internet of Things (IoT), machine-to-machine communication, vehicular communication and video on demand, etc. require very high data rates in short-range communication for better reliability. Antenna systems utilized in traditional communications are not suitable for these applications. Ultra Wide Band (UWB)–Multiple Input Multiple Output (UWB–MIMO) antennas have proved to fit these requirements owing to their improved capability and reliability in short-range communication. The major challenge in designing the UWB–MIMO antennas is to reduce the mutual coupling effects among multiple antennas. In this paper, various techniques for mutual coupling reduction are presented and analyzed such as Electromagnetic band-gap (EBG) structures, meta-materials, parasitic or slot, and stub structures, neutralization lines, etc. [ABSTRACT FROM AUTHOR]

In this article, a multiple input multiple output quadrate frequency bands modified PIFA antenna is introduced for 4G LTE and WLAN applications. The quadrate proposed antenna covers LTE 1800 (1.71-1.88 GHz), LTE 1900 (1.85-1.99 GHz), UMTS (1.92-2.17 GHz), LTE 2300 (2.305-2.400 GHz), LTE 2500(2.50-2.69 GHz), WLAN (2.400-2.484 GHz5.15-5.75 GHz) specified by IEEE 802.11a/b/g/n/ac and WiMAX (3.3–3.6 GHz). Then, the PIFA antenna is used as 2×1 MIMO antenna as a radiation element. The overall dimensions of the single antenna are 50×35×0.8 mm³ and the MIMO antenna is 50×70×0.8 mm ³ while both are realized on FR4-epoxy substrate. To reduce mutual coupling between PIFA antennas at MIMO configuration, Defected Ground Structure (DGS) along with parasitic double split ring resonator is used. The antenna performance is confirmed by the construction of the antenna prototype and measuring its characteristics in terms of reflection loss coefficient, gain, and radiation properties. The extracted outcomes show a good correlation between the simulation and experimental results that candidate it to satisfy mobile communication requirements. [ABSTRACT FROM AUTHOR]

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This work demonstrates the design of a single band Electromagnetic Band Gap (EBG) antenna by employing an open stub EBG microstrip of a patch antenna for better achievements in terms of its performance to be utilized in a reconfigurable harvester to operate over a wide input power range. The EBG antenna has been used to gather RF energy and a FET-transistor has been obtainable to determine and control the power flow with the intention to operate at the same time for a different level of input power. The measured data of the EBG antenna shows a directivity of 8.52 dBi, a gain of 7.18 dBi, a return loss of -27 dB with a radiation efficiency of 84.3%, showing a clear enhancement in directivity, peak realized gain, and radiation efficiency by 41.76%, 25.61%, and 17.12% respectively compared with a regular reference antenna; without utilized the EBG structure. Moreover, the harvester design accomplishes 40% of RF-DC power conversion efficiency over a wide dynamic input power range from -15 to 27 dBm, and its peak is around 78%. The harvester is designed to work at the ISM band for 915 MHz and is suitable for Wireless Power Transfer (WPT) uses. [ABSTRACT FROM AUTHOR]

The cognitive radio (CR) opens new paradigms of opportunistic utilization of unused frequency spectrum through spectrum sharing. Dynamic spectrum access (DSA) provides an effective solution to channel congestion with the help of software-defined radio in cognitive radio networks (CRN). Software defined radio (SDR) offers manipulative wide spectrum sensing and reconfigurable transmission properties between licensed primary user (PU) and unlicensed secondary user (SU). The opportunistic spectrum sharing elicits the need for hardware compatibility from a common radiating antenna for extra-large band spectrum scanning. This paper proposes a novel compact antenna for wide spectrum sensing to utilize vacant channel opportunity in wireless cognitive radio sensor network (WCRSN). The antenna design comprises the combinational effects of fractal slots and electromagnetic bandgap structure on compact FR4 substrate 12 × 18 × 1.6 mm2. The circular polarization improves the feasibility of antenna for orientation-free scanning of spectrum through corner truncation. The novel antenna design exhibits large measured impedance bandwidth from 0.79 to 12.0 GHz compatible with Zigbee, Bluetooth, GPS, GSM, LoRa, WiFi and other UWB applications. The antenna offers average gain 2.59 dBi over entire operating frequency range and validates compatibility for spectrum sensing in WCRSN as per FCC standards. [ABSTRACT FROM AUTHOR]

A co-planar waveguide (CPW)-fed dual-band circularly-polarized (CP) disc-shaped monopole antenna with an electromagnetic band gap (EBG) array is presented for Wi-MAX, WLAN, and ISM band applications. The proposed monopole antenna is comprised of an arc-shaped stub (in the middle), a C-shaped strip (on the left), and an inverted L-shaped strip (in the right). The circular polarization is produced by truncating an arc in the T-shaped radiator, and the antenna is placed over an EBG array to achieve broader impedance and axial ratio bandwidths. The impedance bandwidth and axial ratio bandwidth (ARBW) in the first resonating band are 36.73% (2–2.9 GHz) and 21.16% (2.24–2.77 GHz), respectively. The antenna covers (2.4–2.48 GHz) WLAN/ISM band, (2.5–2.69 GHz) Wi-MAX band, and (2.38–2.49 GHz) Bluetooth application. The impedance bandwidth in the second resonating band is 6% (5.65–6 GHz), which covers (5.72–5.87 GHz) ISM band and (5.72–5.85 GHz) WLAN band. The CPW-fed disc-shaped antenna with an EBG array has dual band radiation characteristics, improved gain and radiation efficiency, compact size, and simple, light weight, and easy design with no vias required. The radiation characteristics of the proposed antenna are measured, and they agree well with the simulated results. [ABSTRACT FROM AUTHOR]

Electromagnetic noise (EMI) affects efficiency of a gadget, proximity devices and human beings, necessitating the noise mitigation. Introduction of Electromagnetic Band Gap (EBG) structure in PCB as plane pairs helps for high-speed operations. In this paper, the planar L-bridge embedded pattern-type EBG structure is designed to mitigate the noise. Experimental verification of the designed EBG type with various geometrical parameters is carried out by altering the geometrical parameters of the unit cell with 18 cases. All the cases are simulated for the frequency sweep 0.1–10 GHz. Simulation results are compared with theoretical calculations and measurement results. It is found that they are in good agreement. The depth in noise levels can be efficiently altered by changing air gap, line length and unit cell width. In order to validate the EBG, a continuous plane is considered and found that EBG helps to mitigate the noise level in the higher frequency. [ABSTRACT FROM AUTHOR]

In this article, a triple-band wearable monopole antenna fed by a coplanar waveguide (CPW) with an integrated electromagnetic bandgap (EBG) array is proposed. The monopole antenna consists of an asymmetric inverted U-shaped strip, a horizontal branch, and an L-shaped ground stub, which can generate the 2.45/5.8 GHz wireless local area network (WLAN) band and the 3.5 GHz worldwide interoperability for microwave access (WiMAX) band. To reduce the influence of antenna radiation on the human body, a triple-band 3 × 3 EBG array has been integrated into the back of the monopole antenna. The EBG unit is composed of two rectangular rings and a circular ring, and the operating frequencies correspond to the triple bands of the monopole antenna. In this paper, the impedance and radiation performances of the stand-alone monopole antenna and the integrated antenna are analyzed, and the safety for the human body is evaluated based on specific absorption rate (SAR) values. The proposed triple-band antenna can be used in wearable devices in wireless body area networks (WBANs). [ABSTRACT FROM AUTHOR]

The increasing usage of wireless technology has prompted the development of a new generation antenna compatible with the latest devices, with on-body antennas (wearable antennas) being one of the revolutionary applications. This modern design is relevant in technologies that require close human body contact, such as telemedicine and identification systems, due to its superior performance compared to normal antennas. Some of its finer characteristics include flexibility, reflection coefficient, bandwidth, directivity, gain, radiation, specific absorption rate (SAR), and efficiency that are anticipated to be influenced by the coupling and absorption by the human body tissues. Furthermore, improvements like band-gap structure and artificial magnetic conductors (AMC) and (DGS) are included in the wearable antenna that offers a high degree of isolation from the human body and significantly reduces SAR. In this paper, the development of on-body antennas and how they are affected by the human body were reviewed. Additionally, parameters that affect the performance of this new antenna model, such as materials and common technologies, are included as an auxiliary study for researchers to determine the factors affecting the performance of the wearable antenna and the access to a highly efficient antenna. [ABSTRACT FROM AUTHOR]

Parasitic currents on the sheaths of the coaxial cables will deteriorate the performance of the antenna, so the choke structures are needed. While a-quarter-wavelength choke sheaths at VHF and UHF are very long, miniaturized ferrite-EBG composited choke structures are proposed. The ferrite refers to ferrite magnetic beads. Electromagnetic bandgap (EBG) element is consisted of multi-section metal tubes with length relatively shorter than a-quarter-wavelength. The integrated structures are formed by arranging EBG elements and beads alternately along the coaxial line. The proposed choke structures combine the wideband choke performance of the ferrite beads and the high efficiency of the EBG structures. Furthermore, due to the difficulty of the quantitative measurement of the choke structures in an open space, a measuring setup designed in a transmission line model is devised. The choking effects of the proposed structures can be characterized by the $\vert \text{S}_{21}\vert $ parameter of the measuring device, as the direction of the currents flowing on the sheaths of feeding cables are the same as that of the currents on the inner conductor of the measuring device. Meanwhile, choking bandwidth, efficiency and size of the ferrite-EBG composited choke structures are compared with that of EBG structures and beads. The influence of different numbers of the proposed structures is studied. A prototype is fabricated and measured. The overall size of the ferrite-EBG composited choke structures is $0.25\,\,\lambda _{\mathrm {L}} \times 0.024\,\,\lambda _{\mathrm {L}} \times 0.024\,\,\lambda _{\mathrm {L}}$ (415 mm $\times40$ mm $\times40$ mm) ( $\lambda _{\mathrm {L}}$ is the wavelength of the lower end of the operating frequency band). The measured choking band ( $\vert \text{S}_{21}\vert < -10$ dB) is in the region of 181–343 MHz.

The compact and robust high-impedance surface (HIS) integrated with the antenna is designed to operate at a frequency of 2.45 GHz for wearable applications. They are made of highly flexible fabric material. The overall size is $45\times \,\,45\times 2.4$ mm3 which equivalent to $0.37\lambda \text{o}\times 0.37\lambda \text{o}\times 0.02$ mm3. The value of using HIS lies in protecting the human body from harmful radiation and maintaining the performance of the antenna, which may be affected by the high conductivity of the human body. Besides, setting the antenna on the human body by itself detunes the frequency, but by adding HIS, it becomes robust and efficient for body loading and deformation. Integrated antenna with HIS demonstrates excellent performance, such as a gain of 7.47 dBi, efficiency of 71.8% and FBR of 10.8 dB. It also reduces the SAR below safety limits. The reduction is more than 95%. Therefore, the presented design was considered suitable for wearable applications. Further study was also performed to show the useful of placing antenna over HIS compared to the use of perfect electric conductor (PEC). The integrated design was also investigated with the worst case of varying the permittivity of body equivalent model which shows excellent performance in term of reflection coefficient and SAR levels. Hence, the integrated antenna with HIS is mechanically robust to human body tissue loading, and it is highly appropriate for body-worn applications.

This work proposed a solution of structures built from stacking several dielectric substrates with the conducting cladding, aiming for electrical contact between them [perfect electric conductor (PEC)–PEC]. At mm-wave frequencies, surface roughness or imperfect flat surfaces present possible gaps that cause severe unexpected leakage. Many engineers overlooked this problem. To prevent this leakage, we propose transforming one of the PEC–PEC surfaces into artificial magnetic conductors (AMCs), creating a PEC–AMC layer that suppresses any leakage even with no contact between the surfaces where the gap is less than a quarter wavelength. A wideband multilayer pyramidal horn antenna using substrate-integrated gap waveguide (SIGW) technology is proposed as an example that highlights the proposed solution. In each layer of the horn, the opening is surrounded by periodic cells to suppress leakage and surface waves. In addition, the upper surface surrounding the horn’s opening is surrounded by EBG mushroom cells to act as a soft surface that suppresses the surface waves and reduces the edge diffraction, and, in turn, improves the radiation characteristics of the horn. The horn achieved a gain of 11.5 dBi and 20.5% bandwidth (28.5–35 GHz). The simulated and measured results show excellent agreement with each other. [ABSTRACT FROM AUTHOR]

This study presents a novel configuration of a cuboidal quad-port ultra-wideband multiple-input and multiple-output antenna with WLAN rejection characteristics. The designed antenna consists of four F-shaped elements backed by a partial ground plane. A 50 Ω microstrip line is used to feed the proposed structure. The geometry of the suggested antenna exhibits an overall size of 23 × 23 × 19 mm3, and the antenna produces an operational bandwidth of 7.6 GHz (3.1–10.7 GHz). The notched band characteristic at 5.4 GHz is accomplished by loading a pair of spiral electromagnetic bandgap structures over the ground plane. Besides this, other diversity features such as envelope correlation coefficient, and diversity gain are also evaluated. Furthermore, the proposed antenna system provides an isolation of −15 dB without using any decoupling structure. Therefore, to validate the reported design, a prototype is fabricated and characterized. The overall simulated performance is observed in very close agreement with it's measured counterpart. [ABSTRACT FROM AUTHOR]

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Abstract In this paper, the authors present a proposal for an application of electromagnetic bandgap (EBG), for suppression of grating lobes, in frequency selective surfaces (FSS), not yet studied in the literature. An alternative type of EBG with square holes was proposed to reduce the computational effort in simulations. The study consists of an application of a rectangular periodic array of cylindrical and square holes in FSS dielectric substrate to create rejection bands and suppress specific resonant frequency modes. We built four prototypes and compared measured results with simulated results obtained with ANSYS HFSS. Simulations and measurements show suppression levels up to 6 dB. A good agreement between the results is observed. The FSS with EBG with square holes allows a simulation time 70 % lower than FSS with EBG with cylindrical holes.

In this paper, a moderate gain monopole antenna is proposed for GSM and Wi-Max applications. The antenna structure is constructed from a traditional printed monopole on Roger substrate of 3006 family. To enhance the antenna performance ultimately, an Electromagnetic Band Gap (EBG) layer is introduced to the antenna structure. A numerical analysis is applied based on a Finite Integral Technique (FIT) of CST Microwave Studio (CSTMWS) formulations to characterize the EBG unit cell in terms of S-parameters, dispersion and reflection diagram, as well as the constitutive electromagnetic properties. The antenna performance is tested numerically with and without the EBG structure in terms of S-parameters and radiation patterns. It is found that the proposed antenna provides an excellent matching, S11< −10 dB, at 1.85 and 3.3 GHz with 2.88 dBi and 5.8 dBi gain, respectively. Nevertheless, the Finite Element Method (FEM) based on Ansoft High Frequency Structure Simulator (HFSS) software package is invoked to compute the antenna performance. The antenna structure is fabricated and tested experimentally. Finally, an excellent agreement is found between the obtained numerical results from both software packages and measurements.

In this paper, a conventional mushroom-type EBG unit cell is made compact by etching a C-slot at its conducting surface. Further, the C-slotted mushroom-type EBG unit cell is coupled with a microstrip line using a novel groove-coupling technique to design a notch filter. The arrangement has achieved in the reduction of the electrical size of the mushroom type EBG unit cell by 46:15% and create a stop band suppression of -12 dB. The proposed EBG is applied to notch a narrow band centered at 5:2 GHz along with an ultra-wideband antenna. The far field gain of the antenna is suppressed by -5:8 dBi along the direction of its major lobe at 5:2 GHz. The overall size of the antenna system is 19x27x1:6mm3 which is compact. The performance of the antenna is validated from the simulation and measured results.

Metamaterials in microwave frequency bands have been widely explored in the development and design of antenna structures and arrays. In this paper, the so-called Yang cell have been studied. When these cells are periodically arranged on a plane, the resulting metamaterial structure shows lower band-gap frequencies than structures composed of other unit cells of the same size. The electric and magnetic fields in the first two modes of electromagnetic propagation in the unit cell have been studied. Four equivalent circuit models of the unit cell have been developed in order to easily and quickly obtain the frequency response of the metamaterial structure. These models are explained in this paper, and were validated using full-wave computational electromagnetic methods.

EBG-backed circular patch antenna for multiband applications which is unique is proposed in this study which is useful in the development of smart cities. In CST, the planned EBG-backed circular patch antenna is modeled and built for testing. The suggested antenna is 35 mm in length and 35 mm in breadth. The suggested antenna has return losses of − 52.5 dB, − 44 dB, and − 28 dB at resonating frequencies of 4.5 Gigahertz, 5.2 Gigahertz, and 5.6 Gigahertz respectively. Suggested antenna construction is made up of a circular patch antenna configuration and a unique EBG structure at the ground level. The suggested antenna's bandwidth is 260 MHz at 4.5 GHz operating frequency and 800 MHz at higher operating frequency like 5.2 Gigahertz and 5.6 GHz. At resonant frequencies of 4.5 Gigahertz, 5.2 Gigahertz, and 5.6 Gigahertz, the suggested antenna obtained gains of 3.28 dBi, 5.39 dBi, as well as 4.43 dBi, respectively. The antenna presented meets the requirements of multiband applications. [ABSTRACT FROM AUTHOR]