Main Patch Research Articles

28/38 GHz compact rhombic-shaped antenna for future generations of mobile communications

ABSTRACT It is mandatory for the modern antennas to be designed to operate in the millimetre-wave (mm-wave) range of the electromagnetic spectrum for future generations of mobile communication requires multiband operation of a single antenna. The present work proposes a dual-band antenna to operate at 28 and 38 GHz . The design stages of the proposed antenna and examples of the parametric study performed to arrive at the final antenna design are demonstrated and discussed in detail. The proposed antenna is constructed as a main patch with parasitic element that is capacitively coupled to the main patch through a narrow slot. The main patch is a rhombic-in-shape and excited through a microstrip live with inset feed. This rhombic shaped patch antenna is originally designed to operate at 28 GHz . To achieve the dual-band operation, the geometry of the main patch is modified and is loaded by a parasitic element. The antenna is fabricated for experimental assessment through measurement of the antenna impedance, radiation patterns, maximum gain and radiation efficiency. The proper operation at 28 and 38 GHz is confirmed by experimental verification of the simulation results. Both the simulation and measurements show that the proposed antenna has 50 Ω -matched impedance over the frequency bands 27.7 − 28.4 GHz and 37.7 − 38.4 GHz . The proposed antenna has been designed to enhance the communications system performance when used in the mobile networks through noise rejection by limiting the operation within relatively narrow bands around the resonant frequencies. The values of the maximum gain obtained at 28 and 38 GHz are 6.98 and 8.8 dBi , respectively. The radiation efficiencies of the proposed antenna are 89 % and 87 % , respectively, and the total efficiency is also calculated.

Dual-band millimetre wave MIMO antenna with reduced mutual coupling based on optimized parasitic structure and ground modification

In this study, a high-isolation dual-band (28/38 GHz) multiple-input–multiple-output (MIMO) antenna for 5G millimeter-wave indoor applications is presented. The antenna consists of two interconnected patches. The primary patch is connected to the inset feed, while the secondary patch is arc-shaped and positioned over the main patch, opposite to the feed. Both patches function in the lower 28 GHz band, while the primary patch is accountable for inducing the upper 38 GHz band. An expedited trust-region (TR) algorithm is employed to optimize the dimensions of the antenna components, ensuring the antenna operates efficiently with high reflection at both bands. The antenna demonstrates a gain exceeding 7 dBi at both frequencies. An array of four antennas is configured orthogonally to create a MIMO system with isolation surpassing 19 dB. The isolation is further enhanced through the addition of a circular parasitic patch at the front and modifications made to the ground. The TR method is employed again to optimize their parameters and achieve the desired isolation, exceeding 32 dB at both bands. The MIMO system demonstrates outstanding diversity performance at both frequencies, characterized by low values of the envelope correlation coefficient (ECC) (< 10 − 4), channel capacity loss (CCL) (< 0.03 bit/s/Hz), and total active reflection coefficient (TARC) (< − 10 dB). Additionally, it secures a diversity gain (DG) exceeding 9.99 dB. The MIMO system is manufactured and tested, showing good alignment between simulation and measurement data for all performance metrics.

Co-seismic and post-seismic slip associated with the 2021 Mw5.9 Arkalochori, Central Crete (Greece) earthquake constrained by geodetic data and aftershocks

The co-seismic and post-seismic deformation field associated with the Mw5.9 Arkalochori main shock that occurred in central Crete (Greece) on 27 September 2021 is analyzed using Copernicus Sentinel-1A & 1B images, GNSS measurements and seismological data. The fault geometry is constrained through the joint inversion of multiple datasets and the slip distribution for the co-seismic and post-seismic period is obtained using a homogeneous half-space elastic model and the Steepest Descent Method. The results indicate a blind normal fault striking 215° with a 55° dip to the northwest and the co-seismic slip model suggests a nearly circular main slip patch (8 × 6 km2) with a maximum slip of 0.98 m. Post-seismic displacements started rapidly after the main shock followed by a gradual decay as highlighted by the calculated InSAR time series. The temporal evolution of post-seismic slip is described by a simple logarithmic function, decaying faster at the southwest part of the fault. The cumulative afterslip model suggests that the maximum post-seismic slip of 0.23 m occurred within a similar depth range compared to the co-seismic one, yet with a shift towards the southwest. Post-seismic slip inside the main shock rupture area is sustained, highlighting the slow recovery of locking in the co-seismic slip region. Afterslip (seismic or aseismic) played a dominant role in the early post-seismic period acting complementarily to the main rupture. Indications suggest that the spatiotemporal evolution of the productive aftershock sequence may be driven afterslip, alongside other potential factors.

Microstrip GPS Circular Antenna for Terrestrial Transportation Systems

In this paper, the design, implementation, and evaluation of a microstrip circular antenna is presented and analyzed. This antenna has two resonant frequencies, which are used in the Global Positioning System (GPS). The antenna was built in a low-cost Printed Circuit Board (PCB) with a FR-4 substrate. The top layer of the PCB includes two slots in the main circular patch, which normally is used in a single carrier reception. The radiation pattern of the antenna shows a wide main lobe in the vertical axis, intending to obtain line-of-sight communication links with five or more GPS satellites.

The Brazil Basin Tracer Release Experiment: Observations

Abstract Lightening of bottom water is required to close the abyssal overturning circulation, believed to play an important role in the climate system. A tracer release experiment and turbulence measurement programs have revealed how bottom water is lightened, and illuminated the associated circulation in the deep Brazil Basin, a representative region of the global ocean. Tracer was released on an isopycnal surface about 4000 m deep, over one of the fracture zones emanating from the Mid-Atlantic Ridge (MAR). Tracer that mixed toward the bottom moved toward the MAR across isopycnal surfaces that bend down to intersect the bottom at a rate implying a near-bottom buoyancy flux of 1.5 × 10−9 m2 s−3, somewhat larger than inferred from dissipation measurements. The diffusivity at the level of the tracer release is estimated at 4.4 ± 1 × 10−4 m2 s−1, again larger than inferred from dissipation rates. The main patch moved southwest at about 2 cm s−1 while sinking due to the divergence of buoyancy flux above the bottom layer. The isopycnal eddy diffusivity was about 100 m2 s−1. Westward flow away from the MAR is the return flow balancing the eastward near-bottom upslope flow. The southward component of the flow is roughly consistent with conservation of potential vorticity. The circulation as well as the pattern of diapycnal flux are qualitatively the same as in St. Laurent et al. (2001) but are more robust. The results indicate that diapycnal diffusivity is about twice that invoked by Morris et al. (2001) in calculating the basinwide buoyancy budget. Significance Statement Buoyancy flux into the abyssal waters is required to close the overturning circulation of those waters, an important part of the climate system. This contribution presents a robust view of the strength of that buoyancy flux and the associated circulation.

Compact Liquid Crystal Polymer Based Tri-Band Flexible Antenna for WLAN/WiMAX/5G Applications

In this paper, a new compact coplanar waveguide (CPW)-fed liquid crystal polymer (LCP) based tri-band antenna is presented and fabricated for Wireless Local Area Network (WLAN), Worldwide Interoperability for Microwave Access (WiMAX) and 5th-Generation (5G) systems. The antenna combines two strips with the main radiation rectangular patch and coplanar waveguide ground. The proposed antenna is printed on a LCP substrate with a thickness of 0.1 mm and has a small overall dimensions of 20mm×32mm×0.1mm. To analyze the characteristics, the antenna is designed and fabricated, and then the performance of the antenna is measured and tested. The measurement results show that the proposed antenna has three operating bandwidths, including 2.38-2.79 GHz, 3.27-4.05 GHz, and 4.80-8.44 GHz. To test the flexibility of the antenna, the antenna is simulated and measured in bent configurations for radii of 10 mm and 50 mm. In addition, the antenna is attached to different parts of the human body to test the integration effect in wearable equipment. The experimental results show that the performance of the antenna remains reliable under bending conditions and that the specific absorption ratio (SAR) value meets the European Union (EU) standard. The proposed antenna shows reasonable gains and good radiation characteristics in the operating bands. The flexible, compact, simple design and multiband performance indicates that the antenna is suitable for integration in flexible electronic devices.

Broadside Gain Enhancement of Wideband Monopole Circular Shaped Antenna Using FSS for Sub-6 GHz Applications

This paper introduces a wideband circular patch antenna designed with a frequency selective surface (FSS) for sub-6 GHz applications. The proposed antenna features a monopole circular-shaped patch with a partial ground plane, delivering an omnidirectional radiation pattern in the azimuth plane, resulting in relatively uniform gain in all directions. An FSS metamaterial enhances the antenna's gain and improves the broadside radiation pattern. The design incorporates three inner circular patches connected to the main patch. The FSS utilizes hybrid square/circle loop-based unit cells. The antenna and FSS are simulated using CST software and subsequently fabricated on an FR-4 substrate. The measured results demonstrate an impedance bandwidth of 1.6 GHz with a peak gain of 5.4 dB at 3.5 GHz. The omnidirectional radiation pattern is converted into a directional one by placing a reflector FSS as a bottom substrate layer. The overall structure size is compact, measuring (0.34λ0 × 0.27λ0 × 0.016λ0), where λ0 is the free space wavelength corresponding to the lowest resonant frequency within the operational bandwidth. This design achieves significant antenna size reduction and is well-suited for future sub-6 GHz applications.

Rupture and Afterslip Controlled by Spontaneous Local Fluid Flow in Crustal Rock

AbstractShear rupture and fault slip in crystalline rocks like granite produce large dilation, impacting the spatiotemporal evolution of fluid pressure in the crust during the seismic cycle. To explore how fluid pressure variations are coupled to rock deformation and fault slip, we conducted laboratory experiments under upper crustal conditions while monitoring acoustic emissions and in situ fluid pressure. Our results show two separate faulting stages: initial rupture propagation, associated with large dilatancy and stabilized by local fluid pressure drops, followed by sliding on the newly formed fault, promoted by local fluid pressure recharge from the fault walls. This latter stage had not been previously recognised and can be understood as fluid‐induced afterslip, co‐located with the main rupture patch. Upscaling our laboratory results to the natural scale, we expect that spontaneous fault zone recharge could be responsible for early afterslip in locally dilating regions of major crustal faults, independently from large‐scale fluid flow patterns.

Dual-Band (28/38 GHz) Compact MIMO Antenna System for Millimeter-Wave Applications

The present work proposes a novel design of a dual-band-printed antenna for operation at the millimeter-wave frequencies 28 and 38 GHz that are utilized for the modern and future generations of mobile communications. The antenna is composed of two radiating elements. The first element is the main patch that is fed through a microstrip line with inset feed, and the second element is a parasitic element that is fed through capacitive coupling with the main patch. The design parameters of the proposed antenna are optimized through a complete parametric study to give excellent impedance matching at 28 GHz over the band 27.7–28.3 GHz and at 38 GHz over the band 37.7–38.3 GHz. The surface current distributions at the two operational frequencies are investigated. The designed antenna is used to construct a four-port efficient multi–input–multi–output (MIMO) system. The MIMO system performance is investigated regarding the envelope correlation coefficient (ECC), diversity gain (DG), and the channel capacity loss (CCL) showing very good performance. The single-element antenna and the MIMO are fabricated and experimentally evaluated showing excellent impedance matching over the lower and higher frequency bands, which come in agreement with the simulation results. It is shown that the antenna produces maximum gain of 7.4 and 8.1 dBi at 28 and 38 GHz, respectively. The average radiation efficiencies of the proposed antenna are 88% and 88.8% over the lower and higher frequency bands, respectively. In addition, the coupling coefficients between the MIMO antenna systems are measured experimentally showing very low coupling values resulting in an efficient MIMO system that is suitable for future millimeter-wave (mm-wave) applications.

EFFICIENCY IMPROVEMENT FOR ELECTRONICALLY STEERED DUAL-BEAM ANTENNA BY USING METAMATERIAL BASED RADOME

Efficiency improvement for electronically steered dual-beam antenna by using metamaterial based radome are a PCB based circular-patch antenna design for dual beam steering is presented. This design employs the symmetrical slots inserted into the surface at eight angles of circular-patch antenna, thus, the original circular-patch antenna is reconfigured as consisting of eight small square-patches placed on eight angles and separated by such the slots. The beam steering property of this antenna can be implemented by controlling the on/off state of PIN diodes, which connected between each small square-patches and main patch at each angle of the structure. When the diode is on, the small square-patch becomes a part of radiating patch, whereas is off, the small square-patch becomes the parasitic element. The antenna is designed for the future high altitude platform such as, drone, Aircraft, missile, etc. That can be tracked or commanded from its control station within the given range and without disconnection. This antenna is investigated at 5.8 GHz of frequency and provided the bandwidth at 113 MHz, which is high enough for the unmanned aerial vehicles UAVs application, The antenna provides the gain of 7.13 dB without meta radome and switchable the dual-beam in eight different space quadrants for the azimuth plane by exciting forward bias with binary sequence to the PIN diodes. While it provides the constant tilted beam of 35° and angular width (3dB) 52.4° in the elevation plane and efficiency improvement for the antenna provides a gain of 10.18 dB with meta radome, approximately.

A Multi-Bandwidth Reconfigurable Patch Antenna for Devices in WLAN and UWB Technology Applications

This article introduces a process to design, simulate, and measure a novel multi-band patch antenna with different operation modes, i.e., band centers and bandwidths. Switching between operation modes is possible using a pair of PIN diodes to connect different parts of the antenna with the main antenna patch. Such a reconfigurable design allows for individual control of each frequency range. The main operation mode of the resulting antenna has an impedance bandwidth with two bands, one from 2.4 GHz to 2.73 GHz and another from 3.4 GHz to 5.73 GHz, with a maximum gain of 4.85 dBi and stable radiation patterns. The resulting antenna is suitable for applications using both ultra-wideband technologies and wireless local-area network (WLAN) technologies.

Compact BLE Antenna With a Modified PIFA Configuration for Wearable EMG Monitor

An antenna mounted underneath the top cover of a wearable device, fed by an ultra-low-profile connector, is proposed for Bluetooth-Low-Energy (BLE) communication at 2.4 GHz. As the antenna is to be used for a wearable device, it is essential that it should be compact in size and tolerant against the nearby medium change. The modified planar inverted-F antenna (PIFA) that we propose consists of a main patch and a parasitic element to broaden the antenna bandwidth. The end of the parasitic element is shorted to miniaturize the antenna to 25 by 10.8 millimeters, fitting well inside a watch-type wearable device. Also, the complete ground layer of the antenna makes it radiate well in the outward direction, and minimally interact with the back-side medium. This results in the reflection coefficient being insensitive to the medium change on the backside. The proposed antenna has a peak gain of 3.62 dBi along with 20% efficiency and the impedance bandwidth of 80 MHz (2.4 ~2.48 GHz). To examine the communicative operation of the antenna in practice, the received signal strength indicator (RSSI) of the complete prototype device with the antenna is measured in various postures and orientations, demonstrating reliable connectivity within a typical indoor distance of 10 meters. Lastly, the antenna is embedded in a wearable device, demonstrating electromyography’s wireless monitoring.

Design and Analysis of Pattern Reconfigurable Antenna Based on RF MEMS Switches

The research on reconfigurable antennas has some disadvantages such as low working frequency and large size. This paper presents a Ka-band patch antenna with pattern reconfigurability using RF MEMS switches. The antenna contains one main patch, two sub-patches, two parasitic patches, and two RF MEMS switches. By controlling the states of the RF MEMS switches, the antenna can achieve three different radiation patterns (−8°, 0°, and +8°) at 35 GHz. The pattern analysis was based on the electric field vector addition method. The analytical, simulated, and measured results agree well with each other. Due to its compact and thin structure of 3.7 mm × 5.2 mm × 0.4 mm, this antenna can be applied in fields such as satellites, smartphones, etc.

Outcomes of surgery for coarctation of the aorta based on a new classification system.

To evaluate early- and long-term outcomes of the surgical treatment for coarctation of the aorta based on a new classification system. A retrospective clinical review of 111 patients with coarctation of the aorta who underwent surgery (March 2011 to August 2020) was performed. We categorised coarctation of the aorta into type I, with all three head vessels tightly packed; type II, with the left subclavian artery separated from the two other head vessels; and type III, with all three head vessels separated from one another. Each type included subtype a, with a short isthmic portion, and subtype b, with a long isthmic portion. The median patient age and weight at operation were 8 (range, 1-1490) days and 3.2 (range, 1.9-18.5) kg, respectively. Extended end-to-end anastomosis was performed via sternotomy in 54, via thoracotomy in 12, end-to-side anastomosis in 31, autologous main pulmonary artery patch augmentation in 12, and modified end-to-end anastomosis combined with subclavian artery flap aortoplasty in two patients. There was one (0.9%) case of early mortality and 12 (10.8%) cases of post-operative complications. Two (1.8%) late deaths occurred during follow-up. Five (4.5%) patients underwent balloon dilatation and three (2.7%) underwent reoperation for restenosis of coarctation of the aorta. All patients with type Ia (21 patients, 18.9%) underwent extended end-to-end anastomosis via sternotomy or thoracotomy. According to the early and late outcomes observed in this study, surgical treatment of coarctation of the aorta using the new classification system could be safe and low risk.

Joint Inversion of Geodetic and Strong Motion Data for the 2012, Mw 6.1–6.0, May 20th and May 29th, Northern Italy Earthquakes: Source Models and Seismotectonic Interpretation

AbstractWe present the first rupture models of the two mainshocks of the 2012 northern Italy sequence, determined by jointly inverting seismic and geodetic data. We aim at providing new insights into the mainshocks for which contrasting seismotectonic interpretations are proposed in literature. Sources' geometric parameters were constrained by seismic reflection profiles, 3‐D relocations and focal mechanisms of mainshocks/aftershocks. Site‐specific velocity profiles were used to model accelerograms affected by strong propagation effects related to the Po basin. Our source models differ significantly from previous ones relying on either seismic or geodetic data. Their comparison against geological sections and aftershock distribution provides new insights about the ruptured thrust faults. The May 20th Mw6.1 mainshock activated the Middle Ferrara thrust‐ramp dipping ∼45° SSW‐wards, breaking a main eastern slip patch 4–15 km deep in Mesozoic carbonates (maximum slip 0.7–0.8 m) and Paleozoic‐Triassic basement rocks, and a small western patch in the basement. The May 29th Mw6.0 mainshock featured two separated asperities along the Mirandola thrust‐ramp dipping ∼42° S‐wards: an eastern asperity 4–15 km deep in Mesozoic carbonates and basement rocks (maximum slip 0.7 m) and a deeper western one (7–16 km depth) mainly in the basement (slip peak 0.8 m). On‐fault aftershocks were concentrated within the basement and Mesozoic carbonates, devoiding high‐slip zones. Slip and aftershock distribution was controlled by the rheological transition between Mesozoic carbonates and Cenozoic sediments. Unlike previous thin‐skinned tectonic interpretations, our results point to a complex rupture process along moderately dipping (40°–45°) thrust‐ramps deeply rooted into the Paleozoic crystalline basement.

A simple design and fabrication of polarization reconfigurable antenna for industrial scientific and medical-band applications

&lt;span lang="EN-US"&gt;This paper proposes a simple microstrip patch antenna (MPA) that can reconfigure its polarization states from linear to circular polarization in real-time by means of a PIN diode. An antenna is fed by a 50 Ω coaxial cable through the substrate of Teflon with relative permittivity of 2.15. The proposed antenna possesses a simple patch with a one-sided corner truncated to achieve polarization reconfigurability. A PIN diode is loaded to connect the main patch with a truncated corner and further maintain dual polarization states such as linear polarization (LP) and circular polarization (CP). Advanced design system (ADS) was used as a simulator to simulate the antenna, and a good understanding was obtained between simulated and measured results. Measured results showed a good agreement with simulated results at all working frequencies of interest. It shows minimum reflection coefficient gain with -10 dB scattering bandwidth 100 MHz for LP states and 170 MHz for CP states. It also shows an axial ratio of 1.56 dB for CP, and the cross-polarization level is also in a satisfying range.&lt;/span&gt;

Analysis of Super-Solar Integrated Patch Antenna for Sub-6 GHz and Beyond 6 GHz Millimeter Wave 5G Applications

This article describes a new compact parasitic patch-loaded transparent patch antenna with a copper ground plane for wireless-fidelity (Wi-Fi) and 5thgeneration (5G) millimeter-wave (mm-wave) applications. The proposed antenna uses two rectangular parasitic patches with a rectangular main radiation patch. The L-shaped strips are also added to the main radiation patch and one of the rectangular parasitic patches to cover both the sub-6 GHz and beyond 6 GHz mm-wave 5G frequency spectrums. The same transparent patch antenna with a solar ground plane is built, and its effect is parametrically studied alongside the integration of a polycrystalline silicon solar cell. The proposed antennas with a dimension of 42x30x2 mm23 are fabricated and experimentally validated for impedance and radiation characteristics. In terms of impedance bandwidth, the proposed copper ground plane antenna offers 36.89% (5.04-7.32 GHz), 5.15% (14.35-15.11 GHz), 6.23% (27.08-28.79 GHz), and 21.34% (31.64-39.81 GHz). The solar cell serves as both a photovoltaic generator and the ground plane of the transparent antenna. The same radiating patch with a solar ground plane offers impedance bandwidth of 36.03% (4.47-6.56 GHz), 14.4% (9.6-11.12 GHz), 2.55% (22.14-22.71 GHz), and 27.9% (28.79-39.05 GHz) for 5G applications.

Patch tests and hand eczema: retrospective study in 173 patients and literature review

BackgroundHand eczema (HE) is a highly prevalent, recurrent, and multifactorial disease. It encompasses a group of eczematous diseases that affect the hands, etiologically classified into irritant contact dermatitis (ICD), allergic contact dermatitis (ACD) and atopic dermatitis (AD). Few epidemiological studies in Latin America have investigated the characteristics of patients with this condition and the origin of the disease. ObjectivesTo analyze the profile of patients diagnosed with HE submitted to patch tests aiming to determine its etiology. MethodsA retrospective descriptive study was carried out on epidemiological data and patch tests of patients with HE treated at a tertiary hospital in the city of São Paulo from January 2013 to December 2020. ResultsA total of 173 patients were studied, whose final diagnosis was 61.8% of ICD, 23.1% of ACD and 5.2% of AD, with diagnostic overlap in 42.8% of the cases. The main positive and relevant patch tests were: Kathon CG (42%), nickel sulfate (33%), and thiuram mix (18%). Study limitationsThe number of treated cases and socioeconomic profile was limited to a vulnerable population group. ConclusionHE is a diagnosis in which overlapping etiologies are frequent, with the main sensitizers identified in ACD being Kathon CG, nickel sulfate and thiuram mix.

A continuous frequency tuning Fabry–Perot Cavity antenna with stable radiation performance

AbstractThis paper presents a continuous frequency tuning Fabry–Perot Cavity (FPC) antenna of which the operating frequency can be varied from 4.87 to 5.84 GHz (18.1%). The cavity of the proposed antenna is excited by a double-layer antenna structure, which is made up of a main square patch and a parasitic one. The superstrate is a frequency-selective surface, consisting of 6 × 6 square-patch-type unit cells. The frequency tuning property is realized by employing 48 phase-changing elements placed around the main patch, which forms a reconfigurable high impedance surface (HIS). By controlling the biasing voltages of the varactors inserted in the HIS element, its capacitances and reflection phases can be varied continuously, which leads to a variation of the operating frequency. An antenna prototype has been fabricated and measured for validation. The measured results are in good agreement with the simulated ones. In the frequency tuning range, the measured realized gains have a smaller variation from 10.2 to 14.1 dBi compared with other reported frequency tuning FPC antennas.

Dual-band frequency reconfigurable 5G microstrip antenna

Microstrip Antenna is widely developed and used in modern telecommunications equipment because of its advantages. Microstrip antenna is also used in 5G development which is expected to increase communication capacity and also be able to provide very large data rates. The frequency used in 5G is 28, 38, and 78 GHz. However, the 5G network with high frequency has a weakness: transmitted waves are vulnerable to weather because of their dense waveform. Therefore, the multiband is used to support different frequencies in one antenna. Furthermore, antenna reconfiguration is used to set the antenna to work on a different frequency and adjust different radiation patterns depending on the needs without changing the form of the antenna. This paper proposes the dual-band frequency reconfigurable antenna with RT Duroid 5880 as its substrate using PIN diodes placed between the main patch and secondary patch element and simulated on CST software for 28 GHz and 38 GHz with two conditions, ON and OFF. Both simulated and measured results show that the antenna can work well as intended. During the OFF condition, the antenna only works at 38 GHz, while in the ON condition, the antenna works at 28 GHz and 38 GHz, respectively.