The hybrid of floating stone column by numerical and physical evaluation

Rapid population growth amplifying demand for accommodation and infrastructure has resulted in soft ground being increasingly used in construction. Problems related to soft ground can be remedied by adopting a ground improvement technique. The stone column is one of the most effective and feasible techniques for soft clay soil improvement. Stone columns increase bearing capacity and reduce the settlement of soil. However, soft ground of more than 40 meters depth makes stone column treatment costlier. The design of floating stone columns within soft ground is sometimes needs to adopt. However, this method is not popular compared to the end bearing stone columns due to low mobilised shear resistance and resulted in higher occurrence of punching failure. This research is aimed for addressing the shortcoming floating stone columns with proposing the hybrid dimension floating stone columns. The hybrid stone column size able to increase the mobilised shear resistance, decrease punching failure, and reduce the volume of aggregates. In the present work, finite element analysis was performed using the program PLAXIS 2D. An elastic-perfectly plastic constitutive soil model relation based on the Mohr-Coulomb criterion was utilized to predict the behaviour of soft clay strengthen by stone column. Response Surface Methodology (RSM) was used to optimize the hybrid stone column size with the Design-Expert 6.0.4 software. The laboratory physical model tests were performed based on the sizes of optimum hybrid stone column size proposed by RSM. The results revealed that the optimal parameter of the uniform diameter of 44 mm with a length of 100 mm increases its load bearing capacity of 3260.7 N and the lowest settlement was recorded at a diameter of 24.2 mm with a length of 400 mm to achieve 25.8 mm of settlement. Moreover, the hybrid column size i.e. the first stone column diameter of 43 mm and second diameter of 21.2 mm with the same lengths of 200 mm each diameter able to achieve load-bearing capacity of 3350.9 N and settlement of 24.5 mm. Thus, by comparing with the uniform diameter stone column of 44 mm and length of 400 mm, the hybrid column able to increase the load bearing capacity by 3% and decrease the settlement by 5%. In addition, a good agreement was obtained between the numerical and physical models with variation 25%. In addition, the hybrid stone column size is able to reduce the volume of aggregates up to 40%

Fast design optimization of UWB antenna with WLAN Band-Notch

In this paper, a methodology for rapid design optimization of an ultra-wideband ( UWB) monopole antenna with a lower WLAN band-notch is presented. The band-notch is realized using an open loop resonator implemented in the radiation patch of the antenna. Design optimization is a two stage process, with the first stage focused on the design of the antenna itself, and the second stage aiming at identification of the appropriate dimensions of the resonator with the purpose of allocating the band-notch in the desired frequency range. Both optimization stages are realized using surrogate-based optimization involving variable-fidelity electromagnetic ( EM) simulation models as well as an additive response correction ( first stage), and sequential approximate optimization ( second stage). The final antenna design is obtained at the CPU cost corresponding to only 23 high-fidelity EM antenna simulations

Wideband and UWB antennas for wireless applications. A comprehensive review

A comprehensive review concerning the geometry, the manufacturing technologies, the materials, and the numerical techniques, adopted for the analysis and design of wideband and ultrawideband (UWB) antennas for wireless applications, is presented. Planar, printed, dielectric, and wearable antennas, achievable on laminate (rigid and flexible), and textile dielectric substrates are taken into account. The performances of small, low-profile, and dielectric resonator antennas are illustrated paying particular attention to the application areas concerning portable devices (mobile phones, tablets, glasses, laptops, wearable computers, etc.) and radio base stations. This information provides a guidance to the selection of the different antenna geometries in terms of bandwidth, gain, field polarization, time-domain response, dimensions, and materials useful for their realization and integration in modern communication systems

Slotted Printed Monopole UWB Antennas with Tuneable Rejection Bands for WLAN/WiMAX and X-Band Coexistence

YesFour versions of the compact hexagonal-shaped monopole printed antennas for UWB applications are presented. The first proposed antenna has an impedance bandwidth of 127.48 % (3.1 GHz to 14 GHz), which satisfies the bandwidth for ultra-wideband communication systems. To reduce the foreseen co-channel interference with WLAN (5.2GHz) and X-Band systems (10GHz), the second and third antennas type were generated by embedding hexagonal slot on the top of the radiating patch. The integration of the half and full hexagonal slots created notched bands that potentially filtered out the sources of interference, but were static in nature. Therefore, a fourth antenna type with tuneable-notched bands was designed by adding a varactor diode at an appropriate location within the slot. The fourth antenna type is a dual-notch that was electronically and simultaneously tuned from 3.2GHz to 5.1GHz and from 7.25GHz up to 9.9GHz by varying the bias voltages across the varactor. The prototypes of the four antenna versions were successfully fabricated and tested. The measured results have good agreement with the simulated results.This work is carried out under the grant of the Fundacão para a Ciência e a Tecnologia (FCT - Portugal), with the reference number: SFRH / BPD / 95110 / 201

Design a new notched UWB antenna to rejected unwonted band for wireless communication

This paper presents a slotted design for ultra-wideband (UWB) antenna. Design of a rectangular UWB antenna covering the frequency range 3.1-10.6 GHz, to achieve notch characteristics in the bands at 3.1-8.4 GHz and 8.6-10.6 GHz. By changing the direction of distribution of current to apply this technique by inserting three C-shaped holes and two pairs of rectangular notches below the antenna. The simulation results reveal that the proposed structure is in good accord with the simulation results. The proposed UWB antenna size is (100x90x1.6 mm)3. This proposed design could provide a solution to eliminating bands that interfere in a UWB band depending on the aperture design. The simulated findings reveal that the UWB antenna operates in the 8.5 GHz center frequency range and rejects all frequency bands utilizing slits. This antenna design can provide a solution to remove UWB bands from 3.1-10.6 except for 8.5 GHz which only works. By using the notch, we got a large increase in the gain. makes to be a suitable candidate for X-band-UWB applications

Ultra Wideband

Ultra wideband (UWB) has advanced and merged as a technology, and many more people are aware of the potential for this exciting technology. The current UWB field is changing rapidly with new techniques and ideas where several issues are involved in developing the systems. Among UWB system design, the UWB RF transceiver and UWB antenna are the key components. Recently, a considerable amount of researches has been devoted to the development of the UWB RF transceiver and antenna for its enabling high data transmission rates and low power consumption. Our book attempts to present current and emerging trends in-research and development of UWB systems as well as future expectations

Compact Printed CPW-fed UWB antenna with SRR and Quarter wavelength slot with dual band-notched characteristic

Volume 2 Issue 3 (March 2014

Realizing uwb antenna array with dual and wide rejection bands using metamaterial and electromagnetic bandgaps techniques

This research article describes a technique for realizing wideband dual notched functionality in an ultra-wideband (UWB) antenna array based on metamaterial and electromagnetic bandgap (EBG) techniques. For comparison purposes, a reference antenna array was initially designed comprising hexagonal patches that are interconnected to each other. The array was fabricated on standard FR-4 substrate with thickness of 0.8 mm. The reference antenna exhibited an average gain of 1.5 dBi across 5.25-10.1 GHz. To improve the array's impedance bandwidth for application in UWB systems metamaterial (MTM) characteristics were applied it. This involved embedding hexagonal slots in patch and shorting the patch to the ground-plane with metallic via. This essentially transformed the antenna to a composite right/left-handed structure that behaved like series left-handed capacitance and shunt left-handed inductance. The proposed MTM antenna array now operated over a much wider frequency range (2-12 GHz) with average gain of 5 dBi. Notched band functionality was incorporated in the proposed array to eliminate unwanted interference signals from other wireless communications systems that coexist inside the UWB spectrum. This was achieved by introducing electromagnetic bandgap in the array by etching circular slots on the ground-plane that are aligned underneath each patch and interconnecting microstrip-line in the array. The proposed techniques had no effect on the dimensions of the antenna array (20 mm x 20 mm x 0.87 mm). The results presented confirm dual-band rejection at the wireless local area network (WLAN) band (5.15-5.825 GHz) and X-band satellite downlink communication band (7.10-7.76 GHz). Compared to other dual notched band designs previously published the footprint of the proposed technique is smaller and its rejection notches completely cover the bandwidth of interfering signals

A reconfigurable dual port antenna system for underlay/interweave cognitive radio

An antenna system that is reconfigurable in frequency is presented in this paper as a novel dual port design that serves both undelay and interweave cognitive radio. This 25×40×0.8 mm3 system is composed of two wide slot antennas: the first is designed as an ultra-wideband (UWB) antenna with controllable band rejection capabilities, while the second antenna is reconfigurable for communication purposes. Three slots are etched into the patch of the UWB antenna to obtain band notching in wireless local area network/Xband/International Telecommunication Union bands (WLAN/Xband/ITU) bands which can be controlled by a positive-intrinsic-negative (PIN) diode across each slot. The configuration states of these three diodes are all useable that produces seven band rejection modes plus the UWB operation mode. The second antenna is configured by five PIN diodes to operate either in Cband, WLAN or Xband regions which results in three interweave modes when setting the first antenna for UWB sensing. The design is simulated by computer simulation technology (CST) v.10. S21 results shows good isolation while input reflection coefficient and realized gain results prove system’s scanning, filtering and communication capabilities. This system is new that it gathers the undelay/interweave operation in a single design and when considering its large number of operation modes it looks adequate for many cognitive radio applications

A Planar Dual Notched Band Vivaldi Antenna for Wireless Communication Applications

With the aim of realizing a Vivaldi Antenna (VA) with stop bands for wireless communication applications, this paper introduces a novel, uncomplicated, easily fabricated, and compact planar VA featuring two distinctive rejected frequency bands. The designed VA is engraved onto an FR4-epoxy substrate, measuring 0.4243λ0×0.4296λ0 ×0.01315λ0 at 2.63 GHz. The integration of dual notched band functionality is ingeniously achieved through the implementation of a simple additional strip and a U-formed slit. A physical prototype of the VA was successfully constructed and meticulously measured with the R&S®ZNB Vector Network Analyser. The measured impedance bandwidth demonstrates that the realised VA operates from 2.63 GHz to beyond 12 GHz while effectively excluding two bands: 3.46-4.16 GHz (18.37 %) and 5.32-6.5 GHz (19.97 %). Simulated results indicate that the designed VA can provide stable unidirectional radiation patterns, reasonable realized gain, and acceptable radiation efficiency across its operating ranges, with notable drops observed at the two notched bands. As a result, these findings highlight the practical value of the designed VA for wireless communication applications, particularly in scenarios where the integration of filtering structures in antennas becomes essential to prevent interference with co-existing systems. The presented VA opens new avenues for enhancing wireless communication performance, catering to the increasing demand for reliable and interference-resistant solutions