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A compact wearable four-element dual-band antenna with good isolation is presented here. The antenna constitutes of a circular monopole with slits and slots incorporated into it to generate dual-band function, and a unique defected ground structure (DGS) with vertical stubs to neutralize coupling current and enhance isolation. The proposed antenna has a dimension of 62 × 52 × 0.25 mm3, bandwidth of 3.8–4.43 GHz (15.31%) and 5.25–6.3 GHz (18.18%), and 5.2 dBi peak gain. The specific absorption rate (SAR) analysis in W/kg for 1/10 g tissue exhibits values of 0.877/0.356 at 4.1 GHz and 0.309/0.105 at 5.3 GHz respectively. The antenna radiation characteristics are analysed using characteristic mode analysis. Furthermore, the diversity parameters are investigated, and the antenna exhibits relatively good results with envelope correlation coefficient (ECC) 9.99 dB, total active reflection coefficient (TARC)

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]

The mm-wave antenna, consisting of a reflector, a DGS structure, and two superstates using Taconic (CER-10) and silicon, has been presented in this article. In the proposed antenna, a DGS with a reflector and two superstates is implemented to improve the antenna performance characteristics. The designed configuration (ANT-S5) is resonating on four mm-wave bands m1=41.7241GHz (41.1102-42.347) GHz, m2=48.9655GHz (48.637-49.1061) GHz, m3=63.2414GHz (61.142-66.137) GHz, m4=76.069GHz (73.4655-78.859) GHz and the maximum achieved gain is 12.02dBi at the 41.3103GHz along with the AR<3dB bands (76.1777-77.2794) GHz, (69.662-70.509) GHz. The designed antenna has been simulated on HFSS software and is convenient for 5G mm-wave applications. [ABSTRACT FROM AUTHOR]

The Internet of Things (IoT) era is driving up demand for wireless connectivity, changing the tech sector. The creation of a compact, inexpensive, and effective antenna is crucial for supporting IoT devices. In this study, a hybrid strategy (HS)-based dense rectangular patch antenna for future Internet of Things applications (IoT) is demonstrated. A slotted patch and a partial ground with defected ground structure (DGS) are combined to create HS, leading to in a small antenna with a large impedance bandwidth, good impedance matching, increased radiation efficiency, and high gain. The antenna is designed on an FR4_epoxy substrate with a compact size of 30 × 20 × 0.8 mm3, a dielectric constant of 4.4, a thickness of 0.8 mm, a loss tangent of 0.02 and fed by a 50 O microstrip feed line. It is analyzed and simulated at the operating frequency of 5.2 GHz for ultrawideband (UWB) (3.1-10.6 GHz) applications using high-frequency structure simulator (HFSS) software. The simulation results reveal that the antenna offers a broad bandwidth of 19.9 GHz (3.10 GHz to 23 GHz), a gain of 7.97 dB with an efficiency of 0.9651 (96.51%). The radiation pattern is bidirectional in both the E-plane and H-plane. Hence, the proposed antenna is very promising for future IoT applications due to its compact size and wide bandwidth characteristics. It also enhances connectivity and performance, lowers interference, opens up new applications, and encourages the widespread use of IoT technology, ultimately leading to the development of a more sophisticated and connected society. [ABSTRACT FROM AUTHOR]

The development of electronic systems and wireless communication has led to a proportional increase in data traffic over time. One potential solution for alleviating data congestion is to augment the bandwidth capacity. This study presents a novel asymmetric circular slotted semi-circle-shaped monopole antenna design using a defective ground structure. The extended ultrawide bandwidth is achieved by implementing a design where the semi-circle radiator is etched in a specific asymmetric circular slot. This involves etching a circle with a radius of 1.25 mm at the center of the radiator, as well as a succession of circles with a radius of 0.75 mm along the edges of the radiator. In addition, the ground plane is situated at a lower elevation and features a U-shaped truncation that has been etched onto its surface. The expansion of the impedance bandwidth can be accomplished by making adjustments to the radiator and ground plane. The UWB antenna under consideration possesses a geometric configuration of 21.6 × 20.8 × 1.6 mm3 and the antenna is fabricated using an FR-4 glass epoxy substrate. The UWB antenna operates throughout the frequency range of 2.2–16.5 GHz, exhibiting a gain of at least 3.45 dBi across the entire impedance bandwidth and the maximum peak gain of 9.57 dBi achieved at the mid-resonance frequency of 10.5 GHz. The investigation of the antenna's physical properties is conducted utilizing characteristic mode analysis. The investigation also includes an analysis of the time-domain characteristics, revealing that the group delay was found to be less than 1 ns across the operational frequency range. The predicted and measured findings demonstrate consistency and confirm that the suggested antenna is suitable for electronic systems and wireless applications. [ABSTRACT FROM AUTHOR]

A ultra-wideband (UWB) multiple-inputmultiple-output (MIMO) antenna using double Y-shaped decoupling structure with high isolation and triple notched-band is presented. The designed antenna composed of two orthogonally placed monopole elements, coplanar ground and double Y-shaped branch. The defected substrate structure is used to achieve miniaturization. By slotting successively C-shaped slot, semicircular slot and rectangular slot on the radiation patch and the ground, achieved three notched bands at 3.5 GHz WiMAX, 5.25 GHz WLAN, and 7.5 GHz X-band. The proposed antenna can operate in range of 2.56-12 GHz with triple notched bands of 3.31-3.96 GHz, 4.58-5.67 GHz and 6.57-8.16 GHz. Considering all the results, it can be concluded that the antenna presented has a great performance in terms of good radiation, high isolation (>24 dB), a low level ECC (<0.01) and a high DG level (>9.99), which proves the presented antenna has good prospect in UWB-MIMO systems. [ABSTRACT FROM AUTHOR]

The growing demand for high-speed communication has resulted in developing terahertz (THz) antennas that operate at high-frequency, high-speed, and high data rates. An ultra-broadband functioning four port THz multiple input and multiple output (MIMO) antenna with a defective ground plane as a decoupling structure is proposed in this study. A rectangular metallic patch was changed by integrating parasitic components onto the radiator with the lowered ground plane on a polyamide substrate to obtain the ultra wideband THz frequency operating antenna. The designed THz antenna has been transformed into a MIMO antenna by replicating horizontally and vertically with the separation of 0.08 λ and 0.01 λ, respectively (λ computed at 2 THz). The proposed THz MIMO antenna operates in the 2–10.7 THz frequency range and has an overall substrate dimension of 40 μm x 46 μm × 2 μm. The proposed antenna equivalent circuit is designed to validate the impedance bandwidth of the antenna. The designed THz MIMO antenna has isolation better than 20 dB across the impedance bandwidth. The isolation enhancement is achieved by creating alternate current channels through the defected ground structure of the antenna. The proposed THz MIMO antenna's MIMO diversity features are studied and determined to be ECC

An approach is presented to enhance the isolation of a two-port Multiple Input Multiple Output (MIMO) antenna using a decoupling structure and a common defected ground structure (DGS) that physically separates the antennas from each other. The antenna operates in the 24 to 40 GHz frequency range. The innovation in the presented MIMO antenna design involves the novel integration of two arc-shaped symmetrical elements with dimensions of 35 × 35 × 1.6 mm3 placed perpendicular to each other. The benefits of employing an antenna with elements arranged perpendicularly are exemplified by the enhancement of its overall performance metrics. These elements incorporate a microstrip feed featuring a quarter-wave transformer (QWT). This concept synergizes with decoupling techniques and a defected ground structure to significantly enhance isolation in a millimeter wave (mm wave) MIMO antenna. These methods collectively achieve an impressively wide bandwidth. Efficient decoupling methodologies have been implemented, yielding a notable increase of 5 dB in isolation performance. The antenna exhibits 10 dB impedance matching, with a 15 GHz (46.87%) wide bandwidth, excellent isolation of more than 28 dB, and a desirable gain of 4.6 dB. Antennas have been analyzed to improve their performance in mm wave applications by evaluating diversity parameters such as envelope correlation coefficient (ECC) and diversity gain (DG), with achieved values of 0.0016 and 9.992 dB, respectively. The simulation is conducted using CST software. To validate the findings, experimental investigations have been conducted, affirming the accuracy of the simulations. [ABSTRACT FROM AUTHOR]

Copyright of Gazi Üniversitesi Fen Bilimleri Dergisi Part C: Tasarım ve Teknoloji is the property of Gazi University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This article is aimed at designing an inventive compact-size quad-port antenna that can be operated within terahertz (THz) frequency spectra for a 6G high-speed wireless communication link. The single-element antenna comprises a lotus-petal-like radiating patch and a defected ground structure (DGS) on a 20 × 20 × 2 µm3 polyamide substrate and is designed to operate within the 8.96–13.5 THz frequency range. The THz antenna is deployed for a two-port MIMO configuration having a size of 46 × 20 × 2 µm3 with interelement separation of less than a quarter-wavelength of 0.18λ (λ at 9 THz). The two-port configuration operates in the 9–13.25 THz frequency range, with better than −25 dB isolation. Further, the two-port THz antenna is mirrored vertically with a separation of 0.5λ to form the four-port MIMO configuration. The proposed four-port THz antenna has dimensions of 46 × 46 × 2 µm3 and operates in the frequency range of 9–13 THz. Isolation improvement better than −25 dB is realized by incorporating parasitic elements onto the ground plane. Performance analysis of the proposed antenna in terms of MIMO diversity parameters, viz., envelope correlation coefficient (ECC) < 0.05, diversity gain (DG) ≈ 10, mean effective gain (MEG) < −3 dB, total active reflection coefficient (TARC) < −10 dB, channel capacity loss (CCL) < 0.3 bps/Hz, and multiplexing efficiency (ME) < 0 dB, is performed to justify the appropriateness of the proposed antenna for MIMO applications. The antenna has virtuous radiation properties with good gain, which is crucial for any wireless communication system, especially for the THz communication network. [ABSTRACT FROM AUTHOR]

Some provinces in China require zero discharge of coal mine wastewater, with a focus on the disposal of high-salt water, because evaporation ponds have been completely banned. Deep geological storage (DGS) technology is a novel geological environment solution that uses rock pores and microfissures within deep strata for safely storing liquid or gas to avoid its environmental impact on the biosphere. The author and his research team were the first to put forward the research idea of using DGS technology to dispose of high-salinity brine in coal mines in China and performed related research. Taking a coal mine in the south of Ordos Basin as an example, this study designed a conventional, mine-specific, zero-discharge water treatment process route based on a evaporation–crystallization process. This strategy was tailored to the unique water inflow conditions of the mine. Furthermore, the technical and economic efficiencies were assessed for the generation and treatment scenarios of a four-stage highly concentrated brine solution. In addition, the comparative analysis of the economic prospects of using DGS technology to treat high-salinity brine revealed that combining DGS with post-conventional treatment in secondary reverse osmosis, whose flow quality is 481 m3/h and TDS is 24,532.66 mg/L, can maximize the economic benefits. This integration heightened water resource utilization while maintaining a cost-effective, comprehensive water treatment approach. These results provide a valuable reference value for the future zero-discharge treatment of coal mine water. [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, various Rectangular Microstrip Antenna (RMA) designs operating at 28 GHz frequency for 5G-communication system are performed. All designs are generated and analyzed using a 3D electromagnetic simulation program, ANSYS HFSS (High-Frequency Structure Simulator). Single and array type RMA designs are constructed by using non-contact inset-fed feeding technique. Subsequently, the bandwidth of RMAs is increased by slotting on the ground surface, and adding a parasitic element to the antenna structure. Because of these analyses, for single type RMA, the bandwidth increases from 2.09 GHz to 3.45 GHz. Moreover, for 1 × 2 and 1 × 4 array type RMAs, very wide bandwidths of 7.53 GHz and 4.53 GHz, respectively, are obtained by applying bandwidth enhancement techniques. The success of the study has been demonstrated by comparing outputs of the designs with the some similar, experimental or simulation studies published in the literature. [ABSTRACT FROM AUTHOR]

We propose a broadband decoupled antenna pair for 5G mobile terminals. The broadband decoupled design of this antenna pair is based on the characteristic mode theory (CMA) and defective ground structure. First, CMA is applied to obtain the characteristic current distribution of the antenna, then the characteristic current sensitive regions are optimized to make the antenna introduce new modes and obtain a wide bandwidth. After that, an antenna pair is added with defective ground structure to obtain a wideband decoupled antenna pair that has small size and high isolation. Next, an eight-element MIMO antenna system is constructed with the obtained broadband decoupled antenna pair, and a composite decoupling technique consisting of defective ground structure (DGS) and decoupling strip is applied to the two antenna pairs on the same side of the bezel to improve the isolation. The simulation and prototype test results show that the eight-element MIMO antenna with −10 dB bandwidth of 3.28~5.85 GHz mainly covers the N77/N78/N79/WLAN 5 GHz band, and the antenna pair are only 1.6 mm apart with good isolation (−16.7 dB), the ECC is less than 0.01, and it has a good total efficiency at the main operating frequency. Finally, the effect of a user's hand on the antenna is briefly analyzed to verify the robustness of the proposed MIMO antenna system. [ABSTRACT FROM AUTHOR]

Copyright of Techno.com is the property of Universitas Dian Nuswantoro, Fakultas Ilmu Komputer and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A novel Log periodic patch with a circular slot antenna has been presented here, the perturbation of the shape of the antenna has been done by combining a triangular shape with a semicircular shape. The antenna proposed here is with a DGS structure on its ground plane and its effects on bandwidth and gain enhancement of the antenna are analyzed. The substrate of FR-epoxy material with length, breadth and height 170 mm, 50 mm and 1.6 mm, respectively is taken for implementation of the antenna on it. This proposed antenna operates at 12 GHz to 18 GHz which includes Ku-band with return loss below-10 dB. The parameters of antenna like S-parameters, antenna gain, directivity, VSWR, surface current distribution and radiation efficiency are determined one by one to ascertain its better performance. The simulation as well as the measurement results are comparatively analyzed.

— Technological advances in the field of telecommunications without cables or wireless are growing rapidly by utilizing radio waves as transmission. This happens because people's mobility is currently quite high and requires practicality in the use of devices. The discussion in this paper is about the comparison of the design and fabrication performance of a diamond microstrip patch antenna composed of a 2x4 element array using DGS and without using DGS. The design was carried out using the CST 2018 simulator. The DGS was placed on a PCB ground plane with an epoxy fiberglass substrate having a dielectric constant of 4.58. This is measured by improving the value of VSWR, return loss, and bandwidth. The application of the working frequency used by the microstrip antenna is at (2401-2495) MHz for WIFI (Wireless Fidelity) networks. Microstrip antennas have a narrow bandwidth shortage, so they require bandwidth widening using the DGS (Defected Ground Structure) technique in the form of dumbbell square ahead. The resulting bandwidth is 15 MHz wider than a microstrip antenna without DGS. This research is in accordance with the antenna test parameters, which have a return loss value of -24.3dB, VSWR 1.12 and a bandwidth of 34 MHz.

In this study, various Rectangular Microstrip Antenna (RMA) designs operating at 28 GHz frequency for 5G-communication system are performed. All designs are generated and analyzed using a 3D electromagnetic simulation program, ANSYS HFSS (High-Frequency Structure Simulator). Single and array type RMA designs are constructed by using non-contact inset-fed feeding technique. Subsequently, the bandwidth of RMAs is increased by slotting on the ground surface, and adding a parasitic element to the antenna structure. Because of these analyses, for single type RMA, the bandwidth increases from 2.09 GHz to 3.45 GHz. Moreover, for 1 × 2 and 1 × 4 array type RMAs, very wide bandwidths of 7.53 GHz and 4.53 GHz, respectively, are obtained by applying bandwidth enhancement techniques. The success of the study has been demonstrated by comparing outputs of the designs with the some similar, experimental or simulation studies published in the literature.

This paper presents the design and realization of a simple and low-profile, four-port multiple-input-multiple-output (MIMO) antenna operating in a mm-wave band supporting 5G communication technologies. As part of the design methodology, the initial stage involved the development of a conventional monopole patch antenna optimized for operation at 26 GHz, which was matched to a 50 Ω stepped feed line. Afterward, a square-shaped defected ground structure (DGS) with semi-circle slots on the edges was placed on the ground to improve the isolation, and the circular and rectangular slots were incorporated as DGSs to optimize the antenna impedance bandwidth. Etching semi-circular-shaped slots on the ground plane achieved more than 34.2 dB isolation in the 26 GHz operating band. In addition, an arrangement of four symmetrical radiating elements was positioned orthogonally to minimize the antenna's physical size and improve the isolation. The proposed MIMO antenna's overall dimension was 25 × 25 mm 2 , which was printed on a Rogers 5880 substrate at a width of 0.787 mm and ε r = 2.2. The proposed antenna covered the 5G mm-wave band with a 10 dB bandwidth ranging from 25.28–28.02 GHz, whereas the maximum gain attained for the proposed structure was 8.72 dBi. Additionally, the implementation of these slots effectively mitigated mutual coupling, resulting in reduced envelope correlation coefficient (ECC) values. Furthermore, other MIMO performance metrics, including channel capacity loss (CCL), mean effective gain (MEG), and diversity gain (DG), were analyzed for the proposed structure. The obtained results indicate its suitability for various usage areas, such as smart devices, mobile phones, and sensors in 5G applications. [ABSTRACT FROM AUTHOR]

The modern electronic device antenna poses challenges regarding broader bandwidth and isolation due to its multiple features and seamless user experience. A compact vase-shaped two-port ultrawideband (UWB) antenna is presented in this work. A circular monopole antenna is modified by embedding the multiple curved segments onto the radiator and rectangular slotted ground plane to develop impedance matching in the broader bandwidth from 4 to 12.1 GHz. The UWB monopole antenna is recreated horizontally with a separation of less than a quarter wavelength of 0.13 λ (λ computed at 4 GHz) to create a UWB multiple input and multiple output (MIMO) antenna with a geometry of 20 × 29 × 1.6 mm3. The isolation in the UWB MIMO antenna is enhanced by inserting an inverted pendulum-shaped parasitic element on the ground plane. This modified ground plane acts as a decoupling structure and provides isolation below 21 dB across the 5–13.5 GHz operating frequency. The proposed UWB MIMO antenna's significant modes and their contribution to antenna radiation are analyzed by characteristic mode analysis. Further, the proposed antenna is investigated for MIMO diversity features, and its values are found to be ECC < 0.002, DG ≈ 10 dB, TARC < −10 dB, CCL < 0.3 bps/Hz, and MEG < −3 dB. The proposed antenna's time domain characteristics in different antenna orientations show a group delay of less than 1 ns and a fidelity factor larger than 0.9. [ABSTRACT FROM AUTHOR]

This paper introduces the research on the elements that could lead to the DGS issue of Mini LED BLU, as well as a theoretical model built based on the research result. By performing a variety of experiments studying the relationship between several elements, this DGS issue was confirmed to be caused by electrochemical corrosion under the joint impact of water steam infiltrate and electric potential difference between metal pattern on the product. In this specific circumstance, the two necessary condition for DGS issue to happen are electric potential difference between 2 nd Cu layer pattern in LED zone and 1 st Cu layer pattern on the G‐ bus, and the water steam infiltrated from the via hole left for the LED chip soldering. The water steam infiltrated then diffuse through the 1 st Resin layer and the time cost for the water steam to reach the position where electric potential difference exists is in a direct proportion to the distance from such point to the soldering via. Moreover, the larger that electric potential difference is, the higher probability of DGS issue happening is, while the relationship between this probability and the distance mentioned previously is in an opposite way. Overall, by applying several optimization such cancelling the hedgehopping 1 st Cu pattern and adding extra inorganic insulating layer protection on the design of product, and applying an extra cathode protection design, the DGS issue was significantly resolved. [ABSTRACT FROM AUTHOR]

This paper presents a novel compact circular shaped fractal monopole patch antenna (FMPA) with defected ground structure (DGS). The suggested fractal geometry has been created by using an iterated function system (IFS). The primary aim behind the inclusion of this fractal geometry is used to achieve miniaturization and wideband performance. The complete geometry of the prescribed FMPA for 5G applications is constructed by incorporating fractals with square and star with eight segments; in each segment we create a square with a rotation of 45° from one segment to another. The dimension of proposed fractal geometry is 14 x 6 mm². The bottom plane of the antenna consists of defected ground structures (DGS) to acquire better isolation and miniaturization. The proposed structure provides a good performance metrics such as gain, and reflection coefficient. The substrate used in this work is Rogers RO4003C, which has a dielectric constant of 3.55, a high of 0.2 mm, and loss tangent of 0.025. Computer Simulation Technology-Microwave Studio (CST) is used to evaluate this antenna. The suggested antenna operates at 26 GHz with an impedance bandwidth of 0.357 GHz along with maximum reflection coefficient of – 24.426 dB. The prescribed antenna attains a peak gain of 3.83 dB, maximum radiation efficiency of 95.78 % and desired radiation patterns by maintaining its compact size. [ABSTRACT FROM AUTHOR]

This study aims to ensure that geometry is the most difficult subject to understand, aspects of the difficulty of learning geometry for students, and suggestions for reducing difficulties. This study uses an exploratory mixed methods design. Students of mathematics education teacher candidates in semesters 3-7 as research subjects were selected by purposive sampling. The data collected in this study used a questionnaire technique, interviews, and the value of learning outcomes for the last 4 years. The results showed that geometry is the most difficult subject, the external learning difficulties factor is dominated by the aspects of the material and learning methods. In addition, references, media, and online learning are also discussed factors. Meanwhile, students' learning difficulties internally from the aspect of motivation and intelligence. One solution suggested to educators is to take advantage of the collaboration of DGS with the Geometry module in learning in dealing with learning difficulties. Tujuan penelitian ini adalah untuk memastikan bahwa geometri merupakan matakuliah yang paling sulit dipahami, aspek kesulitan belajar geometri pada mahasiswa dan saran untuk mengurangi kesulitan. Penelitian ini menggunakan Eksploratory mixed methods design. Mahasiswa calon guru pendidikan matematika semester 3-7 sebagai subjek penelitian dipilih dengan teknik purposive sampling. Teknik pengumpulan data menggunakan teknik angket, wawancara dan nilai hasil belajar selama 4 tahun terakhir. Hasil penelitian menunjukkan bahwa geometri merupakan matakuliah paling sulit, faktor kesulitan belajar secara eksternal didominasi dari aspek materi dan metode pembelajaran. Selain itu, referensi atau bahan ajar, media dan pembelajaran secara daring juga menjadi factor yang dibahas. Sedangkan kesulitan belajar mahasiswa secara internal dari aspek motivasi dan intelegensi atau kemampuan keruangan. Salah satu solusi yang disarankan kepada pendidik adalah memanfaatkan DGS yang dikolaborasikan dengan Modul Geometri dalam pembelajaran untuk menangani masalah kesulitan belajar.

A dual band microstrip antenna for WIMAX and WLAN applications is analyzed and presented in this paper. The proposed antenna has semicircular slot in patch and Defected Ground Surface (DGS) technique for the improvement of its bandwidth and gain. Computer Simulation Technology (CST) software is used to design and simulate the performance characteristics. The proposed antenna has the dimensions as 28 x 26.6 mm2. The fabricated antenna provides a good reflection coefficient of -48dB and -44.5dB at a center frequency of 3.4GHz and 5.5GHz. Gain achieved by the antenna is 2.72dB and 3.87dB for WLAN and WIMAX application. Good agreements have been found between simulated and measured results. These results confirm that the fabricated antenna is very promising for WLAN and WIMAX applications.

Wireless technology is a wireless communication technology that is currently widely used by the public to exchange information. The current information exchange is growing as communication requirements rise. The antenna design needs to be improved in order to boost bandwidth. Microstrip antennas are one kind of antenna that can be used for wireless communication. Meanwhile, to improve the bandwidth value of the antenna can be done using the Defected ground structure or DGS technique. The results of testing the microstrip array circular patch antenna with DGS at 2462 MHz frequency show that it has a maximum gain of 15.7 dBi at a frequency of 2530 MHz and a return loss value of -19.3 dB with a VSWR value of 1,242. There is a type of directional radiation pattern in the antenna of the Microstrip Array with DGS. This study's findings indicate that the Circular Array Microstrip antenna with DGS has a bandwidth of 73 MHz while the Circular Microstrip Array without DGS has a lesser bandwidth of 28 MHz.

Background: Hip pain can be difficult to attribute to one single specific cause, both clinically and radiographically. Yet, there are often subtle signs that point to the nature of the pathology differentiating intra-articular from extra-articular causes of pain. Aim of the Work: The purpose of this study is to investigate and evaluate the accuracy of sonographic findings compared with magnetic resonance (MR) imaging findings in the diagnosis of different causes of chronic hip pain in adults in order to consider it as an adequate practical alternative when MRI primary assessment is not. Patients and Methods: This is cross sectional study included 45 patients with chronic hip pain was conducted at Department of Radio-diagnosis, Ain Shams Universities and other private centers. Result: The study is based on four findings that constitute the undergoing pathologies causing chronic hip pain, and were used as points of comparisons between the two imaging modalities to determine their ability to identify each. Conclusion: Despite the fact that Ultrasound requires a skilled practitioner, it can be a reliable imaging modality in assessing tendon pathologies and we suggest it should be used not only as a complementary procedure to MR but also an effective alternative. [ABSTRACT FROM AUTHOR]

A wideband multiple-input multiple-output (MIMO) antenna for C-band applications is presented in this paper. It consists of 2 × 1 hexagonal motifs which serves as radiating elements. The side of each hexagonal element is 5.73 mm and the overall dimension of the proposed MIMO antenna is 30 × 20 × 1.6 mm3. The hexagonal motifs are embedded on inexpensive FR-4 lossy substrate. Thereafter, a circle with radius 1 mm is etched at the center of each hexagonal motif. Inverted L-shaped stubs are employed to attain efficient isolation between the nearby antenna elements. Four inverted L-shaped stubs are included to further enhance the isolation and eliminate the antenna size increment simultaneously, by suppressing the surface waves. Before using the decoupling approach, the MIMO antenna had an impedance bandwidth of 6.7 GHz and an isolation of −20 dB. The suggested antenna's impedance bandwidth and isolation are 5.83 GHz and −52 dB, respectively, after using a decoupling approach (inverted L-shaped stub). The proposed MIMO antenna had a peak gain and radiation efficiency of 3–7 dBi and better than 90% (with decoupling), 2.75 to 6 dBi and greater than 60% (without decoupling). To verify the proposed design, a prototype was developed to compare the simulated parameters with the measured one. The envelope correlation coefficient (ECC) was less than 0.05, and channel capacity loss (CCL) less than 0.3 was achieved with DGS. Besides, scattering matrix such as return loss S11 and transmission coefficient S21 between two elements, radiation pattern, and current distribution was also favorable. Thus, the proposed MIMO antenna is advantageous to be used for C-band applications such as developing new generation air-borne and space-borne radars, as well as X-band applications. [ABSTRACT FROM AUTHOR]

For the 5G applications of future sub-6 GHz a novel planar very low compact MIMO antenna is designed with improved isolation and impedance matching with T-shaped ground plane and mode analysis is presented here. A very low compact substrate with an area of 48 mm × 24 mm spiritual leaf shape radiating patches are situated in the same direction and maintained a separation distance of 2 mm. To improve the isolation and improved bandwidth, a remodeled structure of T-shaped grounded stub is placed among the pair of radiating antenna elements. The spiritual shaped antenna maintain a −10 dB required operating band of 2.43–3.01 GHz (580 MHz) and 3.19–3.84 GHz (650 MHz) with an isolation more than 20 dB maintained between antenna elements. The spiritual leaf shape antenna offers a radiation efficiency of 94.4 & 86.99% and its peak gain about 7.2 & 6.3 dBi. The simulated isolation is greater than 30 dB thought the dual-band with a maximum isolation of 54 dB. For this MIMO design diversity gain is around 10 dBi, channel capacity loss is less than 0.2 bits/s/Hz, group delay <1 ns and envelope correlation coefficient (ECC) which is lower than 0.0478. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

A novel Log periodic patch with a circular slot antenna has been presented here, the perturbation of the shape of the antenna has been done by combining a triangular shape with a semicircular shape. The antenna proposed here is with a DGS structure on its ground plane and its effects on bandwidth and gain enhancement of the antenna are analyzed. The substrate of FR-epoxy material with length, breadth and height 170 mm, 50 mm and 1.6 mm, respectively is taken for implementation of the antenna on it. This proposed antenna operates at 12 GHz to 18 GHz which includes Ku-band with return loss below-10 dB. The parameters of antenna like S-parameters, antenna gain, directivity, VSWR, surface current distribution and radiation efficiency are determined one by one to ascertain its better performance. The simulation as well as the measurement results are comparatively analyzed. [ABSTRACT FROM AUTHOR]

An Ultra-Wide Band (UWB) MIMO antenna working at millimeter-wave is proposed in this research. It is composed of eight radiating elements with various shapes. It is designed with a rectangular structure and various carved slots. The carved slots are used to increase the antenna's bandwidth. The antenna's radiating elements are placed near one another, and thus, isolation is widespread. In order to improve the isolation of the MIMO antenna, parasitic elements and a defective ground structure are used. Antenna parameters such as Correlation Coefficient (CC), Envelope Correlation Coefficient (ECC), Diversity Gain (DG), and Total Active Reflection Coefficient (TARC) depend on the isolation. Parasitic elements with a rectangular form are positioned between the radiating patches. Rectangular-shaped ground structures with defects comprise the ground plane. An FR-4 substrate is used to fabricate the antenna. The analysis of the antenna shows that there is less than -14dB return loss, less than -40dB isolation, less than 0.0010 crosscorrelation, less than 0.10 TARC, and higher than 500MHz bandwidth. The antenna uses a fractional bandwidth higher than 35% (UWB) for the 6GHz frequency and operates on a variety of bands. This antenna is suitable for many different wireless system applications. [ABSTRACT FROM AUTHOR]

• Optical mechanics is applied to cylindrical shells. • The theoretical calculation method of DGS under cylindrical shell is established. • Reliability of DGS calculation of cylindrical shell fracture is proved. • Application range of DGS method is extended. In this paper, the transmitted digital gradient sensing (DGS) technique is applied to analyze stress singularity at the tip of an arbitrary oriented crack in a cylindrical shell. A thoretical model of the opitcal path near the tip of the inclined crack in a cylindrical shell under mixed-mode fracture is proposed based on the geometric optical imaging principle. An optical governing equation of DGS technique is established to relate the mixed-mode stress intensity fractors (SIFs) at the crack tip to the shell geometry parameters and the inclined crack sizes, and the angular deflection contours are theoretically plotted using this govering equation. Uniaxial tensile tests are carried out on polymethyl methacrylate (PMMA) cylindrical shells containing an edge crack with different inclined angles, and the optimal calculation area for the exaction of SIFs is determined from linear elasitic fracture mechanics. The effects of shell radius, shell thick, crack length, and crack angle on the mixed-mode SIFs are studied, respectively. These results show that the DGS technique is effective and accurate to evalute the stress singulary around an arbitrary oriented cracks in cylindrical shells. [ABSTRACT FROM AUTHOR]

Abstract 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.

The development of electronic systems and wireless communication has led to a proportional increase in data traffic over time. One potential solution for alleviating data congestion is to augment the bandwidth capacity. This study presents a novel asymmetric circular slotted semi-circle-shaped monopole antenna design using a defective ground structure. The extended ultrawide bandwidth is achieved by implementing a design where the semi-circle radiator is etched in a specific asymmetric circular slot. This involves etching a circle with a radius of 1.25 mm at the center of the radiator, as well as a succession of circles with a radius of 0.75 mm along the edges of the radiator. In addition, the ground plane is situated at a lower elevation and features a U-shaped truncation that has been etched onto its surface. The expansion of the impedance bandwidth can be accomplished by making adjustments to the radiator and ground plane. The UWB antenna under consideration possesses a geometric configuration of 21.6 × 20.8 × 1.6 mm3 and the antenna is fabricated using an FR-4 glass epoxy substrate. The UWB antenna operates throughout the frequency range of 2.2–16.5 GHz, exhibiting a gain of at least 3.45 dBi across the entire impedance bandwidth and the maximum peak gain of 9.57 dBi achieved at the mid-resonance frequency of 10.5 GHz. The investigation of the antenna’s physical properties is conducted utilizing characteristic mode analysis. The investigation also includes an analysis of the time-domain characteristics, revealing that the group delay was found to be less than 1 ns across the operational frequency range. The predicted and measured findings demonstrate consistency and confirm that the suggested antenna is suitable for electronic systems and wireless applications.

The increased traffic in e-commerce, cloud-based processing, social media, and online video streaming demands higher data rates. The current 4G has reached the bottleneck, due to which it may not be able to fulfill the high data demand, so the focus is drifting toward millimeter wave (mmWave). The mmWave spectrum ranging from 30 to 300 GHz offers wide bandwidth with low latency, which finds its application in various communication fields, including 5G cellular. Despite its atmospheric attenuation and non-line-of-sight (NLOS) propagation, most countries are currently adopting mmWave 5G at the 28/38 GHz band due to less atmospheric attenuation, low path loss exponent, and low signal spread at these bands. The single-element patch antenna is a compact solution for mmWave applications, but its performance is inferior in terms of bandwidth, gain, and radiation efficiency. The array antennas have overcome these demerits, as it has shown a significant increase in bandwidth, gain, and radiation efficiency. Still, it has a limitation on data rate support. As a result, Multiple-Input-Multiple-Output (MIMO) technology can increase the data rate to 1000 times through spatial diversity and multiplexing techniques. So, to refine the performance further, there is a need to comprehend the MIMO antenna structures designed so far at mmWave. This paper presents the planar MIMO antenna structures developed so far, categorized here as slot, coplanar waveguide, defected ground structures, tapered/Vivaldi, meta-surface/metamaterial, dielectric resonator, and flexible antennas. The performance of these designs is compared based on bandwidth, gain, isolation, efficiency, and radiation pattern. This article also discusses the effects of slots, partial ground, and decoupling structures on impedance matching, bandwidth, and isolation levels. Also, a thorough discussion of the design issues and future work to be undertaken is discussed in this here.

In this paper, an implantable antenna with a semi‐circular slotted patch and a Z‐shaped slotted defective ground structure antenna for biotelemetry applications have been proposed. The antenna resonates at WMTS and ISM bands of 1.42 and 2.42 GHz, respectively. The antenna is compact in size with dimensions of 8 × 9 × 0.635 mm3. To validate the semi‐circular dual band antenna structure, the optimized design is fabricated on Rogers RT/duroid 6010 high dielectric substrate material. The same substrate material is adopted as the superstrate. The experiment was carried out in skin mimicking gel for both WMTS and ISM frequency bands. The designed semi‐circular slotted antenna has peak gain values of −20 dBi, at 2.42 GHz. The observed front‐to‐back ratio at the ISM band is 15.8 dB. The maximum specific absorption rate computed is within safe limits and meets IEEE safety criteria. [ABSTRACT FROM AUTHOR]