Slot Cut Research Articles

An improved design of circularly polarized microstrip antenna for 5G communication

This research paper explores the performance of four circularly polarized microstrip antenna designs tailored for 5G applications. As 5G technology continues to advance, antenna design is pivotal in realizing its potential. The designs, labeled Design 1 through 4, undergo rigorous analysis, encompassing axial ratio, gain, and impedance bandwidth. Notably, Designs 2 and 3, featuring strategic slot cuts, exhibit strong axial ratios suitable for circular polarization within the 5G frequency range. Design 4 introduces an L-shaped feeding line, showcasing unique characteristics albeit with trade-offs. Conversely, Design 1, without slot cuts, demonstrates suboptimal circular polarization performance. This study discusses the significance of these findings within the context of 5G networks, emphasizing the relevance of antenna design choices. As 5G technology evolves, this research offers valuable insights for optimizing antennas in the quest for efficient 5G communication systems.

Slotted Substrate-Integrated Waveguide Leaky-Wave Antenna with Improved Backward Scanning Bandwidth and Constant Gain in X-band

An H-shaped slotted leaky-wave antenna (LWA) is proposed based on balanced composite right/left-handed (CRLH) transmission lines (TLs) to improve the backward scanning bandwidth and achieve constant gain. The proposed antenna consists of a substrate-integrated waveguide (SIW) unit cell array configured by an H-shaped slot cut in the top layer of the SIW and a patch embedded beneath the H-shaped slot. The proposed design improves the backward scanning bandwidth compared to planar SIW LWAs. The measured beam radiation is in the range from −79° to 80° over the frequency range of 7.6–12.5 GHz. Moreover, a constant gain of greater than 10 dB is achieved over the entire X-band frequency range.

Broadband design of corner slot cut sectoral microstrip antenna

ABSTRACT Varying sectoral angle wideband designs of slot cut sectoral microstrip antenna are proposed. Amongst all, slot cut 120° sectoral patch yields maximum bandwidth of 924 MHz (61.44%) with broadside pattern and peak gain of 8.1 dBi. Against equivalent circular and 90° sectoral patch, the proposed design gives 20% and 10% increase in the bandwidth, respectively. Design methodology to realise similar antenna as per the specific frequency is presented that yields similar response. Simulated results have been experimentally verified, which show close agreement.

Posterior cruciate ligament reconstruction using PCL inlay technique with the patient supine in bicruciate ligament injury reconstruction

BackgroundSurgical reconstruction of the posterior cruciate ligament (PCL) can be technically challenging given the proximity of the popliteal artery to the PCL tibial insertion. This "no-safe zone" makes some knee surgeons less confident and willing to perform this surgical procedure.Surgical techniqueWe present a PCL tibial inlay reconstruction technique using a set of instruments involving three tools (a slot cut, a bone plug positioner, and an impactor).ConclusionThis set of instruments allows a more reproducible posteromedial approach and to produce a PCL tibial slot in a posterior cruciate ligament inlay reconstruction with the patient supine in bicruciate ligament injury reconstruction.

Strengthening Existing Concrete Structures with Fibre Reinforced Polymers (FRP) in the New Version of Eurocode 2

This paper aims to introduce the content of Annex J “Strengthening of Existing Concrete Structures with CFRP” of Eurocode 2 [1]. This is first time that the design of adhesively bonded reinforcement with CFRP has been introduced in the European regulations through an informative annex. Annex J considers two different bonded strengthening techniques: externally bonded reinforcement (EBR) that consists of bonding CFRP strips or sheets to the surface of concrete elements, and near surface mounted reinforcement (NSM) that consists of embedding a CFRP strip or rod to a slot cut in the concrete cover. Since, the content of Annex J is new, asummary and background related to all aspects required for designing CFRP strengthened systems for concrete structures, are given in this paper.

Stable High-Gain Linearly and Circularly Polarized Dielectric Resonator Antennas Based on Multiple High-Order Modes

Dielectric resonator antennas (DRAs) under high-order multiple-modes resonator (MMR) for stable high gain are proposed in this communication. The approach is to implement slot cuts on the surface of DR for reconstructing the electric field distribution of high-order resonance modes. In this way, the sidelobes are reduced and two high-order modes are reallocated to construct a continuous wide band. Various MMR configurations were proposed in this work. First, a DRA operating in TE <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{\mathrm {x}}_{031}$ </tex-math></inline-formula> and TE <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{\mathrm {x}}_{051}$ </tex-math></inline-formula> modes is proposed with a pair of loaded slots to realize a fractional bandwidth (FBW) of 26% and a stable gain as high as 8.3 dBi within the desired passband. Second, a DRA with TE <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{\mathrm {x}}_{051}$ </tex-math></inline-formula> and TE <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{\mathrm {x}}_{071}$ </tex-math></inline-formula> modes is developed by introducing two pairs of slots, and an impedance FBW of 12.8% and a stable gain as high as 11 dBi are achieved. Third, three pairs of slots are introduced to the DRA with TE <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{\mathrm {x}}_{091}$ </tex-math></inline-formula> and TE <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{\mathrm {x}}_{0,11,1}$ </tex-math></inline-formula> modes, and an impedance FBW of 6.4% and a stable antenna gain as high as 12.3 dBi are obtained. At last, a circularly polarized (CP) DRA array with four proposed linearly polarized (LP) DRA elements is designed with an impedance bandwidth of 51.8%, a 3 dB axial-ratio (AR) FBW of 32%, a peak gain of 13.89 dBic, and a 1 dB gain bandwidth of 19.9%.

Actively tunable electromagnetically induced transparency on the solid-state plasma metamaterial

A hybrid metamaterial based on a metal-solid-state plasma (SSP) structure has been demonstrated, which actively controls the transparency window by introducing the SSP. The unit cell consists of square patch with a slot and metal cut wire (CW) with SSPs embedded. The designing of a resonant frequency tuning is intrinsically more difficult than amplitude modulation, which has been extensively researched. By introducing SSP and sophisticated structural design, the frequency shifts 403 GHz when the structure switches between two states. The transmission window is switched by changing the state of SSP, allowing for a dynamical group delay of the terahertz frequency. The linearly coupled Lorentz oscillator model is utilized to explore the underlying mechanism of the actively tunable electromagnetically induced transparency behavior between the bright and bright modes. We provide fascinating possibilities for innovative optical components in certain areas, including ultrafast switching, sensing, and terahertz active filtering.

Thinner Substrate Designs of Modified Ground Plane E–shape Microstrip Antennas for Wideband Response

ABSTRACT Wideband designs of a coaxially fed pair of slot cut square, circular, and equilateral triangular microstrip antennas employing the H-shaped or Bow-tie shaped ground plane profile are presented on an electrically thinner substrate (ht ~ 0.04λg). The modified ground plane yields an optimum impedance matching for the response inside VSWR = 2 circle that gives a wider bandwidth. Among all the slot cut regular shaped microstrip antennas, an optimum response in terms of the bandwidth and gain against the substrate thickness reduction is achieved in E-shaped square microstrip antennas backed by the Bow-tie shaped ground plane. Against the thicker substrate design (ht ~ 0.07λg), it yields bandwidth increment by > 10% and reduction in the substrate thickness by 0.03λg, with a peak broadside gain of 6.2 dBi. An experimental validation is carried out in all the proposed configurations that show close matching with the simulations.

CPW-Fed Penta Band Monopole Antenna for Multiservice Wireless Applications

A compact triple T-shaped stub with meander loaded strip antenna for penta band applications is proposed. The rectangular patch antenna with meandered and open-ended slot cuts is utilized to realize four operating bands at 2.45 GHz, 3.1 GHz, 5.3 GHz, and 6.5 GHz with an impedance bandwidth of 400 MHz (2.15-2.550 GHz), 1000 MHz (2.7-3.7 GHz), 200 MHz (5.4-5.6 GHz), and 200 MHz (6.4-6.6 GHz), respectively. For an additional resonance frequency, the length of the central T-shaped stub is slightly modified which causes the variation in the current distribution. As a result, the resonance frequency of 5.5 GHz is divided into two resonance frequency bands which are operating at 5.25 GHz and 5.85 GHz with an impedance bandwidth of 100 MHz (5.25-5.35 GHz) and 200 MHz (5.75-5.95 GHz), respectively. Furthermore, a parametric reflection coefficient and surface current distribution analysis is carried out to understand the strip and slot behavior at resonance frequency bands. Finally, a prototype is fabricated and its reflection coefficient, gain, and radiation pattern are measured. The experimental result shows that the proposed antenna is reliable for penta band applications.

Multi‐resonator gap‐coupled variations of microstrip antennas backed by rectangular slot cut ground plane

Novel gap-coupled variations of rectangular and circular microstrip antennas backed by rectangular slot cut ground plane are proposed. The slot on the ground plane below each of the patch, reduces the resonance frequency of the fundamental mode, thereby giving wideband response at the reduced frequency. With reference to the gap-coupled design at reduced frequency using the conventional ground plane, a slot cut ground plane design yields a reduction in the total patch area with higher BW and comparable gain values. On thinner Taconic substrate (h < 0.02λg), using rectangular and circular patches, the optimum result is obtained with parasitic patches gap-coupled along the two diagonal axis. In the rectangular patch design, bandwidth of 148 MHz (6.04%), peak gain of 9 dBi, for patch size reduction of 33.33% is achieved, whereas using the circular patches, these values are, 138 MHz (5.48%), 9.2 dBi and 38.4%, respectively. In all the proposed gap-coupled designs, for the maximum possible frequency reduction, BW and gain realized is higher as compared with the gap-coupled design with a normal ground plane.

Experimental and Numerical Study for the Effect of Horizontal Openings on the External Plume and Potential Fire Spread in Informal Settlements

According to recent UN reports, it is estimated that more than one billion people live in informal settlements globally, exposing them to a large potential fire risk. In previous research, it was found that the main fire spread mechanism between dwellings is the external flaming (plume) and radiative heat fluxes from the vertical openings at the dwelling of origin to the surroundings. In this paper, an experimental and numerical study was conducted to quantify the effect of adding horizontal roof openings to the design of informal settlement dwellings to reduce the fire spread risk by decreasing the length of flames and radiation from the external plumes at the vertical openings. In total, 19 quarter scale ISO-9705 compartment fire experiments were conducted using an identical fuel load (80 MJ/m2) of polypropylene and were used to validate a physical computational fluid dynamics model for future studies. Five different total horizontal openings areas (0.0025, 0.01, 0.04, 0.09, and 0.16 m2) were investigated using two horizontal openings designs: (1) four square openings at the four corners of the compartment and (2) one slot cut at the middle of the compartment. It was found that adding horizontal openings decreased the average heat flux measured at the door by up to 65% and 69% for corner and slot cases, respectively. Heat flux reductions were achieved at opening areas as low as 0.01 m2 for slot cases, whereas reductions were only achieved at areas of at least 0.09 m2 for corner cases. The Computational Fluid Dynamics (CFD) model was validated using the experimental results. It successfully captured the main fire dynamics within the compartment in addition to the values of the external radiative heat flux. Further, a new empirical ventilation factor was generated to describe the flow field through both openings configurations which showed strong coupling with the inlet mass of fresh air to the compartment.

Resonant Frequency and Bandwidth of Superconducting Microstrip Antenna Fed through a Slot Cut into the Ground Plane

In this work, an efficient analysis is presented to accurately predict the resonant frequency and bandwidth of superconducting microstrip antenna fed through a slot cut into the ground plane. The effect of the superconductivity of the rectangular patch is introduced in the Full-wave analysis based on Gorter-Casimir two fluid model together with London brothers equations. In order to check the accuracy of the proposed approach, the obtained results have been compared with theoretical and experimental data reported in the literature. Finally, the influence of the slot on the resonant frequency and half-power bandwidth of the superconducting antenna has been investigated.

Switchable Micro-Strip Pin Diode Patch Antenna With Slot Changing Method for Wide Band Frequency Applications

A novel microstrip rectangular patch antenna adopting a quarter-wave transformer feed with switchable resonant frequency capability. Switchable (Reconfigurable) antennas symbolize innovation in antenna design that transforms the classical fixed-form, fixed-function antennas to modifiable (Changeable) structures that can be adapted to the provisions of a time-varying system. Advances in microwave semiconductor processing technologies have thereby enabled the use of compact, ultrahigh quality RF and microwave switches in innovative aspects of antenna design. The creation of dynamic radiating structures that can be reconfigured during the operation is new tools that were made possible to design through the High quality, miniature RF switches (e.g. PIN Diode) provided to the antenna designer. The proposed antenna design is obtained by using a C shaped slot cut on the reference patch that is linked by a thin metallic strip incorporating one PIN diodes to obtain the dual-frequency transection. By dominant the PIN diode prejudice voltage potential (-9 Volts for reverse bias & +9 Volts for forwarding bias), the aerial possibly interchanged separating two dissimilar frequencies. It is indicated through the Simulation results that without any additional matching elements, the proposed. Antenna demonstrates an extremely excellent input coincide designed two resonant frequencies of 3.66GHz and 6.5 GHz. These two resonant frequencies depend on the operation of the diode.

Stub Loaded Rectangular Ring Shaped Tri-Band Monopole Antenna for Wireless Applications

This paper presents, design and equivalent circuit analysis of tri-band parasitically stub loaded rectangular ring printed monopole antenna for wireless communication applications. The printed monopole antenna is designed, fabricated and tested. The measured impedance bandwidth (S11< -10 dB) is 750 MHz (2.22 – 2.97 GHz), 220 MHz (3.65 – 3.87 GHz) and 1.28 GHz (5.23 – 6.51 GHz) covering Wi-Fi, WiMAX and WLAN/Wi-MAX applications respectively. The electrical dimension of monopole is 0.245λ0 × 0.212λ0. The proposed antenna is simple and a low profile structure fabricated using low cost glass epoxy substrate (FR4). The overall size of antenna is 60 × 40 mm2. Using slot cut and parasitically coupled stub loading methods, the tri-band monopole antenna has been realized and measured results are found to be in good agreement with simulated results. The equivalent circuit analysis and mutual coupling between the slots are calculated and presented.

RADIATION FROM A NARROW SLOT IN THE END FACE WALL OF A SEMI-INFINITE RECTANGULAR WAVEGUIDE WITH A DIELECTRIC INSERTION INSIDE. PART 2. CALCULATIONS AND EXPERIMENT

The matching with outer half-space of a segment of rectangular waveguide having a dielectric plug inside and a narrow slot cut in the end wall is studied. Various relations between permittivity of the insert and of the dielectric filling the half-outer space are considered. It is shown that good matching can be attained for a slot of some length by means of using the dielectric insert of certain size inside the waveguide.

A Low-Profile and Wideband Triple-Mode Antenna for Wireless Body Area Network Concurrent On-/Off-Body Communications

In this article, a low-profile and wideband triple-port printed antenna for wireless body area network (WBAN) on-body and off-body communications is presented. Three ports are responsible for exciting three different patterns that are orthogonal to each other, including a vertically polarized omnidirectional pattern and two horizontally polarized broadside patterns with radiated fields polarized along the xand y-directions, respectively. In particular, the vertically polarized pattern is achieved by loading an annular array of metallic vias connected to a pin-fed patch antenna on the bottom, while the horizontally polarized patterns are enabled by a closely spaced modified E-shaped stacked patch on the top with additional slot cuts. The integrated antenna was fabricated and characterized, achieving a measured wide S <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> <; -10 dB bandwidth of nearly 14%, a mutual coupling smaller than -15 dB, and an envelope correlation coefficient of less than 0.01. Further numerical and experimental investigations reveal that the proposed antenna has robust electrical properties under both structural deformation and human body loading. The superior performance indicates that the demonstrated antenna is a promising candidate for WBAN devices that can simultaneously support multiple communication modes as well as for other MIMO communications and sensing systems.

Variations of Slot Cut and Stub Loaded Square Microstrip Antenna for Circular Polarization

Modified technique to produce circular polarization for square, nearly square microstrip antenna using diagonal slots of different shapes, slits, stub at corners of antenna is proposed. Diagonally embedded slots are perpendicular to stubs which yield orthogonal modes to give circular polarization. In-depth explanation for orthogonal mode degeneration using different slots shape, its impact on various antenna parameters and sense of rotation is discussed. VSWR, axial ratio bandwidth greater than 38% and 4.1% is obtained respectively. Resultant gain and cross polar level is 8 and 23 dBi. Antenna parameters are compared for square, nearly square microstrip antenna for different slot shapes. Major contribution of paper is empirical formulation of resonant frequencies corresponding to orthogonal modes from its surface current distribution. Close agreement is observed between simulated and calculated resonant frequency from proposed formulations.

Patch Antenna Performance Optimization and Multi-band Operation Using Single Rectangular Slot

In this paper, an investigation is carried out to see how a single, rectangular shaped slot (cut) can be used to significantly improve the performance of a simple, impedance matched rectangular microstrip patch antenna operating in wireless local area network frequencies. Tests are also extended to show how this type of slot can be employed to achieve multi-band operation. The effects of different slot orientations are also examined. The proposed configurations are simulated using the HFSS software package, where return loss, input impedance (Z-parameter), and radiation patterns are used for the analysis of the different configurations. It is found that this type of patch modification can be used to exceed the performance of much more complex patch designs and to offer outstanding efficiency even at multiple resonant frequencies while generally maintaining the radiation properties of the original antenna it was implemented on and avoiding base frequency shifts, making using this slot much easier than other designs.

Effects of ground plane dimensions on patterns radiated by slot antennas

ABSTRACTUsing a hybrid MoM-UTD formulation, this paper investigates the effects of ground-plane dimensions on the radiation fields of a slot antenna. It is shown that the radiated field strength of a slot cut in a finite ground plane is generally higher than that of a similar slot in a ground plane of infinite extent. Indeed, computational results reveal that the E-plane radiated field strength of a slot is about 3 dB higher when the ratio of the ground plane width to slot length is an even integer; and 1 dB higher when the ratio is an odd integer. In the case of the H-plane, the field strengths radiated by a slot in both infinite and finite sized ground planes are virtually identical, suggesting, therefore, that in this case, the contribution of the edge diffraction is insignificant. Results also indicate that a ground plane thickness of less than 20 mm has negligible effects on the radiation fields, as the strength of coupled fields, which is a manifestation of the effect of the finite thickness of the ground plane, is very small. As a validation, patterns computed compare favourably with experimental data available in the literature.

Circularly Polarized Antennas Inspired by Dual-Mode SIW Cavities

This paper presents a detailed study on a family of circularly polarized (CP) antennas inspired by the dual-mode substrate integrated waveguide (SIW) cavities. The related design methodology has been proposed and summarized for the first time. The field distribution for dual-mode SIW cavities (using TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">102</sub> , TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">201</sub> and TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">103</sub> modes) are first analyzed. Based on the current flow of the orthogonal modes, slot cuts are incorporated on the top surface considering both the phase and current magnitude, which leads to optimal boresight CP radiation. All the feasible slot combining configurations which are able to generate CP radiation for the dual-mode cavities are summarized and characterized. For experimental verification, four low-profile, low-cost and high- efficiency CP antennas using the dual-mode cavities are proposed, analyzed and implemented, including two CP antennas based on the degenerate TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">102</sub> /TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">201</sub> half-mode-like resonators, and a CP antenna as well as its 2-element array using the degenerate TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">103</sub> / TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">201</sub> dual-mode cavity. The measured and simulated results are in excellent agreement. Useful design guidelines are provided. These antennas show a measured bandwidth varying from 2.0 % to 4.1 % and a peak gain ranging from 7.0 dBic to 9.4 dBic, respectively. They demonstrate good CP performance and high radiation efficiency which is better than 88 % in simulation. They offer attractive features including interesting working principle, easy implementation, low-cost, and non-sensitivity to tolerance, appearing as good candidates for high-frequency directive antenna application.