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A Defected Ground Structure, DGS, based on matryoshka geometry is described in this paper. The proposed DGS geometry is outlined and initial design equations are presented. Four prototypes, with resonant frequencies 2.17 GHz, 2.44 GHz, 2.99 GHz and 3.73 GHz, were designed, fabricated and characterized, observing a good agreement between measured and numerical results. Also, the obtained results demonstrated the initial design equations usefulness. The resonant behavior was analyzed in terms of the current density and it is possible to observe the current density blocked at the resonant frequency. When compared with dumbbell DGS, a reduction in the resonant frequency up to 47.19% is achieved, confirming the matryoshka geometry miniaturization properties. Furthermore, still comparing with dumbbell geometry, DGS based on matryoshka geometry are more selective. [ABSTRACT FROM AUTHOR]

This research proposed microstrip antenna design using the Defected Ground Structure (DGS) and horizontal patch gap (HPG) for bandwidth and enhancement purposes. This design is to reduce the weakness of a microstrip antenna, which has small gain and narrow bandwidth. The design was simulated in CST Microwave Studio with a working frequency of 2.4 GHz. The design consists of three stages model, i.e., conventional design, DGS modification, and the combination DGS using a Horizontal Patch Gap (DGSHPG). The radius of the conventional circular patch is 16.7 mm. The substrate has 4.6 of dielectric constant, 1.6 of substrate height, and 0.025 of the loss tangent. The simulation results show that the DGS design produces more bandwidth and gain than a conventional design, where the bandwidth and gain improvement are 421.2 MHz and 1.73 dB, respectively. The DGS model is combined with a gap that separates the circular patch (DGSHPG) to achieve the optimum design. The results show the bandwidth and gain improvement of more than 50% and 18.1% compared to the DGS design, respectively. Other parameter performance also shows improvement, such as a reflection factor with -53.3 dB at the center frequency. The physical change also influences the patch’s radius, where it is reduced around 1.4 mm or 8.4% from the original design. Overall, the proposed design has succeeded in achieving bandwidth and gain enhancement and reducing the patch dimension.

This paper introduces the design of a high-gain wideband microstrip patch antenna for sub-6 GHz 5G communication. The proposed antenna integrates a novel defected ground structure (DGS) for achieving the wide bandwidth. The ground plane uses a triangular strip inserted into the ground plane to improve the performance of the antenna. It also uses the reflective plate to concentrate the side lobes and minimise the production of the back lobe, thereby boosting the main lobe of the radiated signal and thus increasing the gain of the proposed antenna. The proposed antenna uses the FR-4 epoxy substrate with an inset feed technique in its design. The simulation and optimisation of the proposed antenna were carried out with CST Microwave Studio Suite. The antenna design is compact with a dimension of 28:03 23:455:35mm3 and a maximum gain and directivity of 6.21 dB and 7.56 dB respectively, with a radiation efficiency of about 80%. The proposed antenna operates from 4.921 GHz to 5.784 GHz, which covers the 4.9 GHz-5.8 GHz of the sub-6 GHz 5G communications spectrum. Fabricated and measured result of the antenna confirm simulated results.

The work in this article presents the design and realization of a low-profile, four-port MIMO antenna supporting fifth-generation (5G) wireless applications operating at a millimeter-Wave (mm-Wave) band. Each MIMO antenna is a 2-element array fed with a corporate feeding network, whereas the single antenna is a patch with a bow-tie slot at the center and slits at the edges. The vertical and horizontal slots are incorporated as a Defected Ground Structure (DGS) to optimize the antenna performance. In addition, a slotted zig-zag decoupling structure is etched from edge to edge on the top side to enhance the isolation. Significant isolation (>−40 dB) is achieved between antenna elements by employing spatial and polarization diversity techniques. The proposed antenna covers the 5G mm-Wave band with a −10 dB bandwidth ranging from 27.6–28.6 GHz, whereas the maximum gain attained for the proposed structure is 12.02 dBi. Moreover, the lower correlation values, higher diversity gain, and lower channel capacity loss make it a suitable contender for 5G MIMO applications at the mm-Wave range. [ABSTRACT FROM AUTHOR]

A micro-strip fed four-port pentagon-shaped 4 × 4 multiple-input multiple-output (MIMO) antenna with a single band-notched characteristic is designed for C band applications. With a frequency range of 2.2 to 3.9 GHz, the band-notched characteristic is centered at 2.6 GHz. The proposed antenna limits S band operation from 2.2 to 3.9 GHz. The proposed design is completed in five steps, each of which yields a different result. The suggested design consists of six stages, each of which results in a progressive increase in gain, bandwidth, and radiation efficiency. It is made on a low-cost FR4 substrate with a thickness of 1.6 mm. To boost gain and bandwidth and to decrease mutual coupling between close elements, a defective ground structure is employed. In the desired frequency of operation, the proposed 4 × 4 MIMO antenna has good return loss characteristics, low mutual coupling, and a low envelope correlation coefficient. The proposed 4 × 4 MIMO with DGS configuration is suitable for the INSAT (Indian National Satellite) receiving system. The ADS tool is used for simulations, and the fabricated patch antenna is tested with a vector network analyzer. The measured and simulated values are nearly identical. The proposed antenna with exhaustive study, simulated return loss, and the radiation pattern are detailed in this paper. [ABSTRACT FROM AUTHOR]

This article introduces a cylindrical dielectric resonator antenna (CDRA) fed with a rhombic ring-shaped tapered feed for Multiple-Input-Multiple-Output (MIMO) applications. The proposed hybrid MIMO CDRA resonates at four frequency bands 2.5, 5.09, 6.8, and 9.0 GHz with isolation levels of 22, 34.22, 30.55, and 18.55 dB. Isolation enhancements are achieved by introducing "L" shaped slots on the partial ground plane. Parametric analysis is performed to validate the optimized dimensions of the tapered feed without and with DRA and defected ground structure. Diversity performance is examined by using envelope correlation coefficient and diversity gain. The proposed antenna operates in the S, C, and X-bands and is suitable for RF communication mobile broadband services, Wi-Fi, radar, and satellite applications. Good agreement is observed between simulated and measured results. [ABSTRACT FROM AUTHOR]

As huge number of applications have been found for a Micro-strip antenna due to its compact and small structure, a quad octagon-shaped dual-band and broadband Micro-strip antenna has been discovered for consumer applications such as (2.1GHz and 5.4GHz). This research work is obtained by combining four octagon-shaped patch structures with a micro-strip feed line and a partial ground structure. The presented microstrip antenna is suitable for providing dual-band output i.e., a frequency band from 1.672GHz to 2.788GHz and a frequency band from 4.876GHz to 6.232GHz. The resonance frequency of the projected antenna is at 2.58GHz and 5.39GHz. Results display that the antenna attains a good return loss(--S_11--) outcome characteristics. The intended antenna can manage 1.116GHz impedance bandwidth (BW) and 50.04% & 24.41% fractional BW below -10dB making it more applicable for WiMAX and WLAN technologies. The antenna has been tested on an FR-4 substrate having a thickness of 1.6mm. The projected antenna has been also examined on CST Microwave Studio. To make the projected antenna for dual-band as well as for broadband the physical profile of four Octagon-shaped patches has been attached to the partial ground. It is important to note that transmitting with higher efficiency and lower return loss can be placed in a distant location from residential areas, which will decrease the chances of people getting affected by radiation. [ABSTRACT FROM AUTHOR]

A compact ultra-wideband (UWB) and triband patch antenna with the partial ground plane is presented in this paper. Initially, the antenna is designed for UWB applications, operating at the UWB portion of the spectrum ranging from 3.1 GHz to 10.6 GHz, then it is modified to operate at three distinct frequencies of 2.45 GHz, 5 GHz, and 10.2 GHz. The proposed antenna is inspired by a classic rectangular patch antenna in which slots, stubs, and defected ground structure (DGS) were introduced to increase its operational bandwidth. Good results in terms of return loss are found in all resonant frequencies as well as for the single wideband. In addition, the proposed antenna has been compared with related works in the literature, to highlight its potential for future UWB and multiband portable devices.

STRENGTHENING TEACHER PEDAGOGICAL COMPETENCIES THROUGH THE USE OF DYNAMIC GEOMETRY SOFTWARE IN MATHEMATICS LEARNING. The selection of strategies, methods, models, and media of appropriate mathematics learning is a form of implementation of a teacher's pedagogical competence. In the 2013 curriculum, the teacher not only sets a scientific approach as a reference in implementing the learning process but also demands innovation to accommodate the right media as well. The role of instructional media, especially dynamic media, is very important in learning mathematics in both elementary and junior high schools. The media was used to explain abstract mathematical problems to be concrete, motivate students, stimulate student learning activities, and help the effectiveness of the learning process. Technological devices such as computers are one of the tools that can be used as dynamic mathematics learning media. Mathematical learning collaboration with ICT devices has been widely carried out in urban and rural areas in Indonesia. Dynamic Geometry Software (DGS) in the form of GeoGebra is a learning medium specifically developed to facilitate the learning of geometry, algebra, and calculus. Therefore, this community service activity (PkM) is intended to strengthen the teacher's pedagogical competence through the use of dynamic learning media using Dynamic Geometry Software (DGS) in the form of GeoGebra in mathematics learning in junior high schools. This PkM aims to train teachers to be able to operate or create mathematics learning media assisted by DGS, especially in learning geometry to students. By making their own, teachers can add insight and increase creativity in making learning media. The supported subjects in these community service activities were junior high school mathematics teachers in Ruteng City. As for the results obtained after the PKM activities, the teachers can operate and create mathematics learning media using DGS in the form of GeoGebra.

After extreme events such as floods, thunderstorms, blizzards and hurricanes there will be devastating effects in the distribution networks which may cause a partial or complete blackout. Then, the major concern for the system operators is to restore the maximum critical loads as soon as possible by available generation units. In order to solve this problem, this paper provides a restoration strategy by using Distributed Generations (DGs). In this strategy, first, the shortest paths between DGs and critical loads are identified. Then, the best paths are determined by using a decision-making method, named PROMOTHEE-II to achieve the goals. The uncertainties for the output power of DGs are also considered in different scenarios. The IEEE 123-node distribution network is used to show the performance of the suggested method. The simulation results clearly show the efficiency of the proposed strategy for critical loads restoration in distribution networks.

Die Gebärdensprache ist nicht etwa nur eine hilfsweise Kommunikation, sondern sie ist ein kultureller Wert an sich – ein Wert der Gehörlosenkultur, die wiederum Teil unseres gemeinschaftlichen Zusammenlebens ist. Man kann sich heute kaum mehr vorstellen – ich habe es zumindest bis vor kurzem nicht gewusst; das sage ich ganz klar –, dass Gebärdensprache einmal bei Strafe verboten,war. Es war ein harter Kampf, bis sie endlich als unverzichtbares Element einer barrierefreien und inklusiven Gesellschaft anerkannt wurde.“ Die Mehrheit der Menschen verständigen sich mithilfe von Sprachen, die akustisch produziert und über ihr Gehör aufgenommen werden. Jedoch gibt es auch Menschen, denen es durch ihre Gehörlosigkeit nicht möglich ist, sich lautsprachlich zu verständigen. Sie nutzen zur gegenseitigen Verständigung einen anderen Sprachmodus, nämlich die Gebärdensprachen. Von Geburt an Gehörlose und Frühertaubte bilden die Mehrheit der Gehörlosengemeinschaft. Wichtig ist aber festzuhalten, dass nicht alle Gehörlosen Gebärdensprachen benutzen und dass auch Hörgeschädigte, hörende Eltern gehörloser Kinder, etc. Teil der Gehörlosengemeinschaft sein können .Die moderne linguistische Erforschung der Gebärdensprachen begann erst in den 1960er Jahren. Zu diesem Zeitpunkt ging ein Grossteil der Sprachwissenschaftler davon aus, dass die Gebärdensprachen keine eigentlichen Sprachen sind. Sie galten als eine Art Pantomime oder als eine gebrochene Form der gesprochenen Sprache .

This paper studies the electromagnetic properties of defected ground structure (DGS) with von Koch snowflake fractals. First, the snowflake fractal is employed in the dumbbell shaped DGS, and we have discovered that it has the characteristics of a low-pass filter and the out-of-band rejection increases with fractal iterations. In consideration of fabrication accuracy and performance, the third iteration has been adopted. Based on this structure, we have designed a narrow-band filter and a wide-band filter to verify our theory. From the simulated and measured results, we can see that the out-of-band rejection level has been greatly improved. The proposed structure can be applied in communication planar circuits.

In this paper we present the design and fabrication of a two-antenna array to resonate at 5.8 GHz, a frequency that satisfies a host of applications, especially those associated with the ISM band, but including IoT applications. The design incorporates several techniques to improve figures of merit and reduce its size. The array presents a measured bandwidth of 617 MHz (from 5.503 to 6.120 GHz, or 10.63% about the central frequency) when built on a thin substrate, and of 455 MHz (from 5.517 to 5.972 GHz; 7.84%) when fabricated using a thicker one. The simulated gains were of 6.89 dBi and 7.63 dBi, whereas the measured ones were 6.7 dBi and 7.2 dBi, respectively. Size reduction is better than 30% and the simulated efficiencies are higher than 90%.

This paper presents a printed multiple-input multiple-output (MIMO) antenna with the advantages of compact size, good MIMO diversity performance and simple geometry for fifth-generation (5G) millimeter-wave (mm-Wave) applications. The antenna offers a novel Ultra-Wide Band (UWB) operation from 25 to 50 GHz, using a Defective Ground Structure (DGS) technology. Firstly, its compact size makes it suitable for integrating different telecommunication devices for various applications, with a prototype fabricated having a total size of 33 mm × 33 mm × 0.233 mm. Second, the mutual coupling between the individual elements severely impacts the diversity properties of the MIMO antenna system. An effective technique of orthogonally positioning the antenna elements to each other increased their isolation; thus, the MIMO system provides the best diversity performance. The performance of the proposed MIMO antenna was investigated in terms of S-parameters and MIMO diversity parameters to ensure its suitability for future 5G mm-Wave applications. Finally, the proposed work was verified by measurements and exhibited a good match between simulated and measured results. It achieves UWB, high isolation, low mutual coupling, and good MIMO diversity performance, making it a good candidate and seamlessly housed in 5G mm-Wave applications.

This work presents a quad-port Multiple Input Multiple Output (MIMO) wideband antenna that operates in the terahertz (THz) frequency range is designed and analyzed. To improve MIMO performance, a defective ground structure (DGS) is used. A rectangular metallic patch was altered by adding parasitic elements to the radiator with the lowered ground plane on a polyamide substrate in order to achieve the wideband THz operating frequency. The THz antenna was turned into a MIMO antenna by replicating horizontally and vertically with a spacing of 0.05 λ and 0.002 λ, respectively (λ calculated at 1.7 THz). The designed THz MIMO antenna, comprising 40 μm × 46 μm × 2 μm, operates across the 1.7-10.4 THz frequency region. The THz MIMO antenna provides isolation of more than 20 dB in the frequency range of 2.8-10.4 THz and more than 10 dB for the frequency of 1.7-2.7 THz. Isolation augmentation is accomplished by establishing different local current channels using the antenna's DGS. The MIMO diversity properties of the proposed THz MIMO antenna are analyzed and found to be ECC<0.004, DG ~ 10 dB, TARC < -10 dB, MEG < -3 dB, and CCL<0.23 bps/Hz over the antenna's operating frequency., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2024 The Author(s).)

In this study, a three-pole hairpin structure was fabricated on the top of the substrate material and an open loop microstrip structure at the ground to give a modified triple-band BPF with a unique design. A Rogers (RT5880) material with εr = 2.2 and thickness of 1.27mm was used to fabricate the proposed structure. The space between two consecutive hairpin resonators has different distances d1 and d2 with values of 0.2mm and 0.4mm respectively. The proposed filter offers a compact size with low return loss. The equivalent LC circuit of the DGS and hairpin structure is obtained with the Ansys electronic desktop and by using simple circuit analysis. The desired microstrip triple-band BPF operates at the Ku band, resonates at 10.28GHz, 12GHz, and 14.62GHz, while the simulated and experimental results are almost identical. The proposed wideband BPF satisfies the International Telecommunication Union ((ITU) region 3 spectrum requirements. Direct Broadcast Service (DBS) and Fixed Satellite Service (FSS) in transmit mode respectively employ the frequency band 11.41-12.92GHz and 14-14.5GHz. [ABSTRACT FROM AUTHOR]

In this paper, a fractal antenna array for telecommunication applications is presented. The proposed antenna array is realized on a Plexiglas substrate, has 1×2 radiating elements, and dimensions of 170mm×105mm. The antenna array is composed of two Koch Snowflake patches and is fed by a Coplanar Waveguide (CPW) transmission line. Radiating elements and the ground plane are printed on the top side of the substrate. Defected Ground Structure (DGS) technique is employed to enhance the bandwidth and improve the impedance matching. The proposed antenna array operates at two frequency bands, 1.08-1.32GHz covering the GPS band and 1.7-3.7GHz covering the GSM 1800/1900, UTMS, Bluetooth, LTE, and WiMAX bands. In addition, the antenna has a good performance with efficiency and peak gain of 82% and 6.3dB respectively. These characteristics allow the antenna to be an attractive candidate for telecommunication systems. Design and analysis of different structures were carried out with Ansys HFSS. [ABSTRACT FROM AUTHOR]

Generally, 6 to 7 patch antennas are used in a mobile for different applications. In this paper, a single antenna is proposed to address several applications in a mobile phone. For this purpose, a Meander line feed planar inverted F- antenna (PIFA) with DGS that radiates at multiple frequencies is deliberated in this work with VSWR < 2 at all the desired frequencies as it provides good isolation among the desired frequencies. Flame Retardant 4(FR - 4) is preferred as substrate (loss tangent,d(0.02)) with thickness of 1.53mm. The ground defected structure resembles as slotted sections with fractal shape. The proposed antenna is radiated at three frequencies such as 1.7GHz (1.64 - 1.82 GHz), 2.4GHz (2.2 - 2.6 GHZ) and 4.8GHz (4.44 - 5.35 GHZ) with a reflection coefficient of -12.9dB, -39dB, - 39dB respectively. With the proposed structure the bandwidth is enhanced by 19% at the upper band with a peak gain of 5.32dBi along with the achievement of linear polarization at all the desired frequencies. The proposed design has a compact dimension of 60X30X1.6mm (0.70x0.35x0.018 wavelengths at lower band) and is well suited for 4G, WLAN, WI-FI and Wi-Max applications. [ABSTRACT FROM AUTHOR]

In this paper, a metamaterial bandpass filter using Split Ring Resonators (SRR) is designed, analyzed, and developed for WLAN applications at 2.4 GHz frequency band. Here, metamaterial bandpass filters with and without Defected Ground Structure (DGS) are designed, analyzed and compared. The filter structure shows a considerable size reduction with 50% fractional bandwidth, quality factor of 2 and wide bandwidth. The simulation results of the proposed filters offered good insertion loss and return loss response. The filters have been modeled, fabricated and their performance has been evaluated using the Method Of Moment (MOM) based electromagnetic simulator IE3D. The dimensions of the proposed filter is 20 × 9 × 1.6 mm which is considerably reduced. The simulated and measured results projected that the proposed metamaterial filters are well suited for WLAN applications. [ABSTRACT FROM AUTHOR]

A wideband multiple-input multiple-output (MIMO) antenna with high isolation for fifth-generation (5G) new-radio (NR) smartphone employment operating at a range from 3.3–5 GHz is presented in the paper. The wideband antenna is comprised of eight identical radiation units and applies defected ground structure (DGS) to offer higher isolation between antenna units. Each of the antenna elements is formed of a C-shaped microstrip line, two triangle-shaped strips and a rectangular strip. The measurement results present that the transmission coefficients of the presented antenna are smaller than −18 dB in the required wideband, and the envelope correlation coefficient (ECC) values are better than 0.005. The realized gain and efficiency of the designed antenna are about 3.5 dBi and higher than 75%, respectively. The volume of this total antenna is 150 × 75 × 7 mm3, and the measurement of each antenna unit is merely 6.8 mm × 7 mm × 0.8 mm (0.077 λ×0.08 λ×0.009 λ, λ is the wavelength of 3.4 GHz). The presented MIMO antenna is suitable for 5G new-radio (NR) smartphone applications.

To meet the requirements of a high transmission rate and strong communication quality for mobile terminals, a planar antenna printed on a 0.8-mm-thick FR-4 substrate is proposed in this paper. The structures are compact, with a size of 23×6 mm2. The performance of a single antenna pair in a 75×35 mm2 ground plane shows the advantages of both ultra-wide bandwidth and high isolation. The operating frequency of −6 dB is 54% (3.3 GHz–5.9 GHz). To solve the mutual coupling effects exiting in the antenna pair, a hybrid strip defected grounding structure (DGS) is added in the middle of neighboring antenna elements, and good isolation performance of lower than −13 dB is achieved. The evolution and analysis of the proposed antenna pair are given to investigate the operating principle. To verify its practicality, an eight-port antenna system in 150×70 mm2 ground plane is constructed along two frames of the smartphone board. The MIMO antenna system performance is simulated and texted. The results show a bandwidth of 3.4–5.2 GHz (−6 dB), an isolation performance lower than −10 dB, an ECC lower than 0.01, and a total efficiency of 46–84%. In addition, the performance of the antenna system under single handheld conditions is also discussed. The correlation results show that the designed antenna pair has good data transmission and interference resistance capability, which proves that this is an excellent antenna model for application in mobile terminals.

A compact and wide-stop band half mode substrate integrated waveguide (HMSIW) filter, incorporated with a hybrid fractal on the upper plane and a complementary split ring resonator (CSRR), along with a defected ground structure (DGS) etched on the bottom plane, is proposed for 5G sub-6 GHz application. A CSRR reduces the resonant frequency causing size miniaturisation by approximately 40% by augmenting the equivalent inductance and capacitance of the CSRR. Further, the low-pass characteristics of the DGS aid in suppressing out-of-band spurious harmonics. A two-pole band pass filter (BPF) is fabricated using FR4 (flame retardant) to validate the design. The results confirm that the proposed filter has a pass band from 3.75 GHz–5.12 GHz with spurious response below −20 dB > 4f0.

We proposed an antenna pair that is applicable for mobile terminals: a type of coupling feed planar antenna that has a size of 28×6 mm2, a wide band, coupling suppression and compact size. Different from the conventional antenna design, the process of band expansion comes from a dual-band antenna pair and is based on characteristic modes theory (CMA). By observing characteristic current distributions, the optimization emphasis is placed on current sensitive parts in antenna structures, which is an effective method to create or modify resonant points for exciting band potential. Meanwhile, the multiple defective ground structure (DGS) is introduced for isolation enhancement. The −10 dB bandwidth of 3.23–5.24 GHz can be realized, and the isolation of two antenna pairs with only 2 mm spacing is lower (−17.34 dB). The eight-port MIMO system constructed by four proposed antenna pairs has been fabricated. The simulated and measured results of MIMO indicate that its −10 dB operating bandwidth can work at N77/N78/N79/WLAN 5 GHz bands. Moreover, a lower ECC of less than 0.04 and a high efficiency of more than 60% can be obtained, which confirms that it is capable of excellent data transmission as a terminal MIMO antenna system.

A unified active power control scheme is devised for the grid-integrated permanent magnet synchronous generator-based wind power system (WPS) to follow the Indian electricity grid code requirements. The objective of this paper is to propose control schemes to ensure the continuous integration of WPS into the grid even during a higher percentage of voltage dip. In this context, primarily a constructive reactive power reference is formulated to raise and equalize the point of common coupling (PCC) potential during symmetrical and asymmetrical faults, respectively. A simple active power reference is also proposed to inject a consistent percentage of generated power even during faults without violating system ratings. Eventually, the efficacy of the proposed scheme is demonstrated in terms of PCC voltage enhancement, DC-link potential, grid real, and reactive power oscillation minimization using the PSCAD/ EMTDC software.

Abstract In this paper, the enhancement of gain and bandwidth of a Minkowski fractal antenna (MFA) with defected ground structure is investigated. The antenna characteristics are studied for first and second iterations by considering complementary split ring resonators in the L‐shaped modified ground plane. The dimensions of the MFA are optimized with computer simulation technology software and the fabricated antenna characteristics are measured using Vector Network Analyzer and Wave and Antenna Training System. From the simulation, the maximum gain of our proposed antenna has been found 5.2 dB. Both bandwidths obtained from simulation and measurement exceed 2 GHz. The results of simulation are in good agreement with measured ones. This proposed antenna is suitable for the applications of various 5G wireless communications.

This article presents a quad‐band multiple‐input multiple‐output antenna with two‐element. Its radiator, composed of four rings, realizes multi‐band function, and isolation between the two antenna elements is improved by using the cross‐shaped defective ground structure and the goblet shaped stub at the center of the back ground plane. The total size of the design is only 25 mm × 32 mm, but it can obtain good performance in the four frequency bands (4.6‐5.0 GHz, 6.82‐7.83 GHz, 10.3‐10.8 GHz, and 14.1‐16.96 GHz), which can be concluded from the simulation and measurement results on the desired bands: (a) the input reflection coefficient (S11) less than −17 dB, (b) the isolation (S21) better than −15 dB, (c) the envelope correlation coefficient below 0.04 and the peak gain greater than 1.23 dBi. The proposed antenna is suitable for wireless communication of small unmanned aerial vehicle operating in the beyond‐line‐of‐sight range. The first of the four bands (4.6‐5.0 GHz) is used for 5G cellular network communication and the other three bands can be applied for downlink of X‐band (7.25‐7.75 GHz) satellite communication, X‐band (8‐12 GHz) and Ku‐band (12‐18 GHz) satellite communication, respectively. [ABSTRACT FROM AUTHOR]

In this paper, the enhancement of gain and bandwidth of a Minkowski fractal antenna (MFA) with defected ground structure is investigated. The antenna characteristics are studied for first and second iterations by considering complementary split ring resonators in the L‐shaped modified ground plane. The dimensions of the MFA are optimized with computer simulation technology software and the fabricated antenna characteristics are measured using Vector Network Analyzer and Wave and Antenna Training System. From the simulation, the maximum gain of our proposed antenna has been found 5.2 dB. Both bandwidths obtained from simulation and measurement exceed 2 GHz. The results of simulation are in good agreement with measured ones. This proposed antenna is suitable for the applications of various 5G wireless communications. [ABSTRACT FROM AUTHOR]

In this paper, a new Defected Ground Structure (DGS) is introduced and analyzed. The effect of the structure's dimensions on the location of the attenuation pole and the cutoff frequency to study the frequency characteristics is investigated. In the following, a lowpass filter with 3 dB cutoff frequency at 3 GHz is designed and optimized using the proposed defected ground structure, and its frequency characteristic is reported. The designed lowpass filter is fabricated to verify the simulation process. Also, simulation results, the equivalent circuit, and the measured results with the Network Analyzer are compared. [ABSTRACT FROM AUTHOR]

This work proposes a novel compact artificial magnetic conductor (AMC) surface backed microstrip antenna of dimension (0.29λ0 × 0.17λ0 × 0.015λ0) for improving the antenna radiation characteristics. The microstrip antenna considered here for performance improvement has a defected ground plane; thus, giving rise to undesired back‐lobe radiation. Thanks to the, in‐phase reflection characteristics of the AMC surface, gain improvement of more than 3 dBi has been achieved with a front‐to‐back lobe ratio improvement of 12 dB. This structure resonates at 5.8 GHz with an impedance bandwidth improvement of 13%. The overall antenna dimensions are (0.67λ0 × 0.8λ0 × 0.13λ0), where λ0 is the free space wavelength. To prove the concept, a physical prototype of the proposed antenna structure has been fabricated and the return loss, radiation pattern and gain have been verified. The obtained results are satisfactory and matching with the estimated results. [ABSTRACT FROM AUTHOR]

This paper suggests a design for dual-band wireless power transfer systems that use E-shape defected ground structure resonator loaded with a 1.5 pF capacitor and U-shape resonator at the top layer. When the two resonators of the proposed design are coupled back-to-back, it transfers to a dual band-pass filter leading to an efficient WPT system working at 0.9 GHz and 1.4 GHz. A compact size of 20 mm × 20 mm is fabricated achieving a WPT efficiency of more than 97% at a distance of 16 mm for both bands. Good concurrences among the equivalent circuit model (ECM), the theoretical studies, and the measurements have been attained. [ABSTRACT FROM AUTHOR]

In this paper proposed dual layer single coaxial feeding DGS printed antenna by cutting some slots from the patch and adding some slits with the patch. It is the very easiest design to achieve our desired application for which it is designed. We compare the proposed antenna with the conventional design and the proposed structure gives a 49.82% size reduction with compare to the conventional antenna. In this paper we analyze the gain, bandwidth, return loss for the desired proposed structure. The proposed structure designed with the help of IE3D electromagnetic solver which uses the Method of Moment (MoM) based analysis. The proposed structure simulated results are verified by a measurement which is carried out by VNA network analyzer. In this paper, proposed design achieved multiple resonant frequencies and they are applicable for different microwave band applications. As per the concern of 1st resonant frequencies, the proposed structure applicable for surface ship radar applications. [ABSTRACT FROM AUTHOR]

Friction is created in the gas seals due to the relative motion of the two fixed and rotary surfaces, causing power dissipation, erosion, heat generation and temperature rise of the surfaces so a distance between two surfaces should be created. In the structure of Dry Gas Seals (DGS), the grooves on the rotating surface are created, which is the key to the gas penetration between the surfaces. The geometrical parameters of grooves would have substantial effect on the amount of leakage, so it is of high importance to indicate the best shape and operating condition of grooves. In this research, the effect of geometric parameters of a DGS with trapezoidal grooves on the leakage rate and open force is investigated. The geometric parameters are the depth of the triangular and square sections, the length of the groove, the angle of the square part and the angle of the groove. The length of the groove has a substantial impact on leakage, and by doubling the length, the leakage rate is raised to 58%. It is concluded that when the angle of the square section is 7° and the angle of groove is 22°, the minimum leakage occurs in the range of parameters studied. Taguchi algorithm is also applied to optimize the shape parameters of the groove to minimize open force and leakage of the seal. Optimal dimensions for grooves in the range of operating conditions in this study are triangle depth = 3μm, quad - depth = 10μm, Length = 8mm, groove angle = 18°, rectangle angle = 5°. The same optimum conditions are obtained by considering energy and exergy terms. [ABSTRACT FROM AUTHOR]

In this paper, a compact, wideband, printed antenna is proposed for millimeter-wave fifth-generation communication systems. The proposed design is a patch antenna with a defected ground structure, in which ground plane defects are utilized to reduce resonance and achieve wideband operation. The optimized antenna dimensions are 2.5 mm × 4.5 mm with a substrate thickness of 0.203 mm. A prototype antenna was fabricated and measured to verify the performance, and it was established that the simulated and measured results were in good agreement. The measured bandwidth was approximately 6.4 GHz (26.5-32.9 GHz) with a peak gain of 5.62 dBi and an efficiency in operational bandwidth of 84%. The compactness, wide bandwidth, and decent gain suggest that the proposed antenna is a potential contender for forthcoming communication systems. [ABSTRACT FROM AUTHOR]