Ring Patch Research Articles

Single‐layer dual‐broadband circularly polarised annular‐slot antenna for WLAN applications

This study proposes a single-layer dual-broadband circularly polarised (CP) antenna that operates at 2.4, 5.2 and 5.8 GHz for wireless local area networks (WLAN) applications. An annular-slot antenna loaded with a lightning-shaped slot for achieving good CP radiation in the WLAN 2.4 GHz band is initially studied. To cover the WLAN 5.2 GHz band as well, the inner circular patch of the aforementioned design is modified as an inner ring patch loaded with a notch and a narrow U-shaped strip. By further embedding a crescent parasitic element into the circular slot of the inner ring patch, the upper CP band is significantly broadened to cover the WLAN 5.8 GHz. Accordingly, the final design can exhibit two wide 3 dB axial ratio bands of 13.3% (2.24-2.56 GHz) and 16.9% (5.01-5.94 GHz), and their corresponding 10 dB impedance bandwidths are 25.9% (2.21-2.86 GHz) and 25.9% (5.05-6.54 GHz). With the advantages of compact size, low-cost, easy integration and dual-broad CP bands, the proposed designs are very attractive for modern wireless communication systems, especially for WLAN applications.

Design of Concentric Circular Ring Patch with DGS for Dual-Band at Satellite Communication and Radar Applications

In this paper, the design of concentric circular ring slot patch antenna with defected ground structure (DGS) is presented. The rectangular patch antenna is slotted with two concentric circular rings on radiating patch. The two diamond shaped patch is added to the microstrip-feed-line. The DGS is considered for obtain dual bands at 6.6 and 9.4 GHz with return loss − 14.7 and − 20.9 dB to operate for satellite communication and radar applications. The VSWR is less than 2 and axial ration is less than 3 dB for these two bands are obtained of proposed antenna. The surface current distribution is presented for analyzing the effect of the slots. It is observed that the simulation and measured values are having good agreement.

SURGICAL MANAGEMENT OF TRICUSPID VALVE INFECTIVE ENDOCARDITIS: A SYSTEMATIC REVIEW AND META-ANALYSIS

Background This meta-analysis compares the early and late outcomes of valve repair versus replacement, the primary surgical strategies for tricuspid valve infective endocarditis (IE). Methods We searched MEDLINE and EMBASE databases until 2016 for studies comparing tricuspid valve repair and replacement. Results The main outcomes were mortality, recurrent IE, and need for reoperation. There were 12 unmatched retrospective observational studies with 1,165 patients (median follow-up 3.8 years, interquartile range: 2.1 to 5.0). The most common indications for surgery were septic pulmonary embolism, left-sided IE, right-side heart failure, and persistent bacteremia. Median repair proportion was 59% and replacement was 41% among studies. The primary repair strategies are vegetectomy, De Vega procedure, annuloplasty ring, bicuspidization, and leaflet patch augmentation. Of valve replacements, 83% were bioprosthetic and 17% mechanical prostheses. There were no differences in perioperative mortality between tricuspid valve repair versus replacement (relative risk [RR] 0.62, 95% confidence interval [CI]: 0.26 to 1.46, p = 0.3). Long-term all-cause mortality was not different (RR 0.61, 95% CI: 0.22 to 1.72, p = 0.4). Valve repair was associated with lower recurrent IE (RR 0.17, 95% CI: 0.05 to 0.57, p = 0.004) and need for reoperation (RR 0.26, 95% CI: 0.07 to 0.92, p = 0.04) but a trend toward greater risk of moderate to severe tricuspid regurgitation (RR 4.14, 95% CI: 0.80 to 21.34, p = 0.09). Furthermore, tricuspid valve repair is associated with lower need for permanent pacemaker (RR 0.20, 95% CI: 0.11 to 0.35, p Conclusions Tricuspid valve repair and replacement offer similar long-term survival. Valve repair may offer greater freedom from recurrent IE and reoperation as well as freedom from pacemaker and should be the preferred approach for patients with tricuspid valve IE.

Negative Reflecting Meta-Mirrors

Using the gradient phase discontinuities that meta-mirrors provide, we show that the incident wave can be reflected anomalously with a broad angle range of negative reflections. Such reversed behaviors promote the immediate applications for the planar meta-mirrors to steer the signals more arbitrarily and the convex meta-mirrors to focus and collimate electromagnetic fields. We practically implement these negative reflecting meta-mirrors through an arrangement of subwavelength ring patches and generate the desired phase distribution by also considering the incident angle. Finally, the experiments are carried out to verify the functionality of the convex meta-mirror firstly, and the performances of the planar meta-mirror are also tested by further building up a dual reflector system with the demonstration of obtaining the plane wave from the convex meta-mirror and then having the well collimated beam negative reflected by the planar meta-mirror. The proposed design should be readily applicable to a wide range of electromagnetic problems, especially for devising smart planar illusion devices, and highly directive antennas mounting on convex surfaces of various platforms.

A compact ultra‐thin ultra‐wideband microwave metamaterial absorber

AbstractThis study presents a new, ultra‐thin compact microwave metamaterial absorber for wideband applications. The proposed metamaterial absorber comprises an outer ring and inner split ring patches on the upper surface and metallic ground in the bottom surface. A dielectric FR4 substrate of thickness 1.6 mm was placed between the top patch and the bottom ground. The designed structure was ultra‐thin of λ0/13.9 thickness with respect to the centre frequency of the bandwidth. The simulation results showed ultra‐wideband absorption of 6.31 GHz from 10.36 to 16.67 GHz above 85% absorptivity, and peaks at 11.1, 13.2, 14.4 ,and 16.2 GHz and full width half maximum of 9.6 GHz. The mechanism of absorption for the proposed ultra‐wideband metamaterial absorber was studied. Also, the polarization behavior was tested under oblique and normal angles of incidence for transverse electric polarization. Due to its asymmetrical design, the proposed structure is polarization sensitive. The designed structure was fabricated and measured, and the practical results were in good agreement with the simulation results.

Design of Single-Layer Microstrip Antennas for Dual-Frequency-Band Ratio Adjustment with Circular Polarization Characteristics

ABSTRACTThis article proposes the design of a single-layer circular polarization antenna for flexible dual-frequency-band ratio adjustment. The antenna consists of an inner circular patch and an outer ring patch that is electromagnetically coupled to the circular patch. The circular patch is fed by two ports of a hybrid chip coupler, and the dual-frequency-band ratio is adjusted by varying the gap distance between the two patches. For verification, the proposed antenna was fabricated to measure its antenna characteristics in a full anechoic chamber, and the results demonstrated that the antenna is suitable for flexible adjustment of the dual-frequency-band ratio from 1.24 to 1.8, with an average axial ratio of 2.4 dB.

X-band Operations Metamaterial Absorber with Extended Circular Ring Topology for Size Reduction

<p>A metamaterial electromagnetic wave absorber consisting of a big circular ring patch with four smaller suppression circular rings is presented in this report. The metamaterial electromagnetic wave absorber introduces the concept of size reduction by suppressing the resonance frequency. An FR4 substrate was used and the incidental wave angles were varied from 0<sup>0</sup> to 60<sup>0</sup>. Simulations results shows peak absorption of 100% was achieved at 10.7 GHz by the absorber for both TE and TM polarization incident waves. Minimum absorption for both TE and TM mode of 90.6% was achieved under TE mode. The metamaterial absorber was being tested with and Ultra-wide band antenna and the results were reported.</p>

An ultra-wideband monopole antenna with a gain enhanced performance using a novel split-ring meta-surface reflector

This article presents the design of an ultra-wideband monopole antenna with a gain enhanced performance using a novel double split ring metasurface reflector. A circular patch configuration is used here as the radiating element for the simplicity and reliability of such structures. The antenna radiates well beyond the ulta wideband (UWB) frequencies but the performance enhancement using double split ring Metasurface reflector is within UWB frequency. The periodic array of dual split ring patches with varying split angles placed in a columnar arrangement is responsible for the metasurface structure to reflect effectively in phase-agreement over a broadband without affecting the impedance bandwidth of the principal radiator. With such a low profile setup (gap between antenna and reflector is in the order of at the lowest operating frequency of the antenna) the wideband gain-enhanced characteristic makes the design versatile enough for numerous practical applications. A high increment in the antenna gain performance (nearly 5.5 dB) is recorded over the UWB frequency range. Experimental results are found to be in good agreement with the simulations. © 2017 Wiley Periodicals, Inc. Microwave Opt Technol Lett 59:1296–1300, 2017

Formation of charge-nanopatterned templates with flexible geometry via layer by layer deposition of polyelectrolytes for directed self-assembly of gold nanoparticles

Nanostructure formation via self-assembly processes offers a fast and cost-effective approach to generate surface patterns on large lateral scale. In particular, if the high precision of lithographic techniques is not required, a situation typical of many biotechnological and biomedical applications, it may be considered as the method of choice as it does not require any sophisticated instrumentation. However, in many cases the variety and complexity of the surface structures accessible with a single self-assembly based technique is limited. Here, we report on a new approach which combines two different self-assembly strategies, colloidal lithography and layer-by-layer deposition of polyelectrolytes, in order to significantly expand the spectrum of accessible patterns. In particular, flat and donut-like charge-patterned templates have been generated, which facilitate subsequent deposition of gold nanoparticles in dot, grid, ring, out-of-ring and circular patch structures. Potential applications are e.g. in the fields of biofunctional interfaces with well-defined lateral dimensions, optical devices with tuned properties, and controlled three-dimensional material growth.

Coding diffusion metasurface for ultra‐wideband RCS reduction

A coding diffusion metasurface is designed and fabricated for ultra-wideband radar cross-section (RCS) reduction. Two kinds of unit cells based on square ring patch are employed to generate the `0' and `1' elements of the coding metasurface. By precise design of the unit cells, a 180° ± 37° reflection phase difference between these cells is achieved over 8.01-22.76 GHz, leading to dramatically reduce the scattering field level by more than 10 dB. To obtain the diffusion far-field pattern of the metasurface, the optimisation algorithm is utilised to calculate the optimal layout of the digital elements. Both full-wave simulation and measurement results verify the capability of the proposed metasurface.

A Wideband Dual-Polarized L-Probe Antenna Array with Hollow Structure and Modified Ground Plane for Isolation Enhancement

A two-element wideband dual-polarized L-probe antenna array with hollow structure is presented in this letter. The hollow structure is applied to offer space for hosting other antennas (e.g., the concept of shared-aperture antenna). Each radiating element is designed with a compact size of 51 mm × 51 mm × 24.5 mm (0.374λ 0 × 0.374λ 0 × 0.18λ 0 at 2.2 GHz) and has a hollow volume of 31 mm × 31 mm × 24.5 mm. With a slotted square ring patch and unique L-probes, the antenna element exhibits a fairly large fractional bandwidth of 45%, ranging from 1.71 to 2.69 GHz. Moreover, a narrow slot and T-shaped metallic structures on the ground plane are introduced to increase the input-port isolation of the proposed antenna array to 26 dB across the entire operating bandwidth. The experimental results indicate that the antenna array has an average realized gain of 10.5 dBi, which correlates well with the simulations.

Wearable Antenna Integrated into Military Berets for Indoor/Outdoor Positioning System

A wearable antenna integrated into a military beret for an indoor/outdoor positioning system is proposed. The antenna consists of a truncated patch and a circular ring patch with four conductive threads. The truncated patch antenna is designed for the Global Positioning System (GPS) L1 band for use in outdoor situations, and the circular ring patch antenna with four conductive threads operates at the TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">41</sub> higher-order resonance mode (915 MHz) with a monopole-like radiation characteristic for indoor positioning systems. The antenna is fabricated using textile materials and is integrated into a military beret. The effects of the antenna deformation due to the shape of the military beret and the effects of the human head are analyzed via both simulation and measurement. The simulated and measured 10-dB return-loss bandwidths of the antenna on the head phantom fully cover the 915-MHz industrial, science, and medical band and the 1.575-GHz GPS L1 band.

A Simple and Efficient Approach to Compute the Operating Frequency of Annular Ring Patch Antennas by Using ANN with Bayesian Regularization Learning Algorithm

A Simple and Efficient Approach to Compute the Operating Frequency of Annular Ring Patch Antennas by Using ANN with Bayesian Regularization Learning Algorithm

Dual‐band circularly polarized microstrip antenna

ABSTRACTA design for dual‐band circularly polarized microstrip antennas with different radiation patterns is described. The design is based on a stacked patch antenna composed of an upper circular patch and a lower ring patch. For the higher operation band, the two patches are simultaneously resonant at the TM21 mode and the stacked patch antenna can produce a conical radiation pattern. As for the lower operation band, only the upper patch is resonant at its fundamental mode and a broadside radiation pattern is obtained. To allow the two radiation patterns to be with circular polarization, 90° hybrid couplers are used to excite the patch antennas at the two operation bands. A prototype designed at the GPS and WLAN bands is constructed. The experimental results demonstrate that the prototype operated at each frequency band has a 3dB‐axial‐ratio bandwidth of more than 15%. Simulation performed with HFSS also validates the measured results. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 59:404–408, 2017

Diversity‐based four‐port multiple input multiple output antenna loaded with interdigital structure for high isolation

A four-port planar multiple input multiple output antenna system employing polarisation and pattern diversity technique is proposed. The antenna system, resonating at 2.4 GHz ISM band, includes a dual polarised two-port cross-patch antenna and an orthogonally polarised two-port square ring patch antenna. Undesired high coupling between elements is reduced by incorporating an interdigital structure on the ground. This reduces coupling between elements by 12.5 dB, ensuring a high isolation of about 28 dB between any set of elements in the antenna system. The overall size of the quad element antenna is about 0.5 × 0.5λ, which makes it fairly compact. The cross-patch antenna has low cross-polarisation levels, which reduces the coupling between its orthogonal elements. The narrow bandwidth of the higher order modes of the square ring antenna is doubled by adding half wavelength slits along its arms. All four elements have a 2:1 voltage standing wave ratio (VSWR) bandwidth of 85 MHz and have low envelope correlation in the operating band. The antenna is printed on a low cost FR4 substrate and does not require any intricate fabrication.

Modified annular ring patch fed cylindrical dielectric resonator antenna for WLAN/WIMAX applications

ABSTRACTThis article investigates modified annular ring patch fed cylindrical dielectric resonator antenna (CDRA) with hybrid mode excitation. The present article comprises of two main aims (i) generation of HE11δ and HE12δ mode in CDRA with the support of modified annular ring patch, both the hybrid modes radiates in broadside direction and (ii) achieve triple band characteristics by using the concept of hybrid antenna. The proposed antenna design is functioning in three different frequency bands, i.e. 1.92–2.3 GHz, 3.13–4.6 GHz, and 5.4–6.5 GHz. The simulated outcomes are verified by using archetype of proposed antenna. The practical outcomes indicate good settlement with simulated outcomes. The proposed antenna structure is appropriate for WLAN/WiMAX applications. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 59:120–125, 2017

A Method of Designing a Dual-Band Sector Ring Microstrip Antenna and Its Application

A dual-band sector ring microstrip antenna operating at the TM11 and TM02 modes is analyzed and then designed in this communication. Unlike previous analyses that use only cavity model or transmission line, a simpler analysis using both models is proposed. Accordingly, several closed equations are derived. Such equations determine the relationship among three important units of construction, namely the radii, the angle, and its operating frequencies, and with the operating factors in a dual-band sector ring patch. The errors between the proposed method and the cavity model are acceptable. The field and radiation patterns of the sector ring patch are also discussed. In addition, these analyses and equations are applied to design a dual-band sector ring microstrip antenna for WLAN. A novel coupling sector ring patch is then proposed to improve the performance of the antenna. The experimental results are in good agreement with the analyses and the simulations. The impedance bandwidths of the antenna are about 40 and 900 MHz with consistent broadside radiation patterns at 2.4 and 5.5 GHz band. Additionally, their measured average gains are about 5.1 and 6.3 dBi, respectively.

A Circularly Polarized Ka-Band Antenna for Continuous Link Reception from GSAT-14

Objective: Design of circular ring patch antenna in Ka-band is described and simulated for receiving the dual polarised beacon continuously from GSAT - 14. Method: Circular ring’s intrinsic geometry selected in this work leads to circular polarization and high radiation efficiency so making it suitable for implementing on array and as well as for practical application where low losses are salient features. Findings: The proposed antenna has shown reliable performance which is measured in terms of Half Power Beam width (HPBW), Side Lobe Level (SLL), cross polarization, gain bandwidth and AR bandwidth at resonant frequency of 20.2 GHz. A truncation in the circle of the circular patch is made in order to meet these performance characteristics of the antenna. Applications/Improvements: The proposed antenna exhibits circular polarisation for any polarised incident wave which is desired in most of the communication applications. Results depict that this antennas can be useful in receiving the GSAT-14 beaco

Hybrid cylindrical dielectric resonator antenna with HE11δand HE12δmode excitation for wireless applications

In this article, dual mode triple band hybrid cylindrical dielectric resonator antenna CDRA for different wireless applications is investigated. It is seen that annular ring shaped patch along with T-shaped printed line behaves as a magnetic and electric dipole concurrently and create HE11I´ and HE12I´ mode in the proposed CDRA. Both of the hybrid modes radiate in broadside direction. The concept of hybrid antenna the combination of annular ring patch and CDRA is used to achieve triple-band feature in the proposed antenna. Ansoft HFSS-EM simulator is used to optimize the proposed antenna. Optimized simulated results have been practically confirmed by using the archetype of proposed antenna. The proposed radiator is applicable in three different frequency bands, that is, 2.24-2.56 GHz, 3.28-4.18 GHz, and 5.36-5.8 GHz. It is appropriate for WLAN 2.4/5.8 GHz and WiMAX 2.5/3.3/5.5 GHz applications.

Low-profile UHF RFID reader antenna with CP radiation and coupled feeding technique

A low profile annular-ring patch antenna with circularly polarized (CP) radiation for radio frequency identification (RFID) reader applications in the ultra-high frequency (UHF) band (922-928 MHz) is presented in this article. Perturbation method is applied by loading a pair of triangular open-notch into the outer circumference of ring patch, and good impedance matching can be determined by using the coupled feeding technique. The overall size of this proposed antenna is 150 mm × 150 mm × 10.4 mm. The measured results show desirable 10-dB impedance bandwidth and 3-dB axial ratio (AR) bandwidth of 3.5% (908-941 MHz) and 0.65% (922-928 MHz), respectively. Stable antenna peak gain and efficiency of 7.2 dBic and 87% are also exhibited, respectively.