Design of dual-frequency broadband planar antenna for high-speed wireless LAN systems

2005 ◽  
Vol 88 (7) ◽  
pp. 11-19 ◽  
Author(s):  
Kazuo Tamakuma ◽  
Hisao Iwasaki
2021 ◽  
Author(s):  
Hatice Kosek

Subcarrier multiplexed (SCM) transmission of multimedia radio signals such as CATV (5-860 MHz), cellular wireless (900 MHz) and wireless LAN (2.4 GHz) over fiber is frequently used to deliver broadband services cost effectively. These multi-channel radio-over-fiber (ROF) links have interesting applications and can connect enhanced wireless hotspots that will support high speed wireless LAN services or low speed cellular services to different customers from the same antenna. The SCM signals need to be demultiplexed, preferably in the optical domain for many reasons. Prefiltering of SCM signals with fiber-based optical filters warrants the use of inexpensive photodetectors and increases network flexibility. However, realizing optical demultiplexing as sub-GHz level is challenging and thus necessitates optical filters with high selectivity and low insertion loss and distortion. We developed a novel sub-picometer all-optical bandpass filter by creating a resonance cavity using two closely matched fiber Bragg gratings (FBGs). This filter has a bandwidth of 120 MHz at -3 dB, 360 MHz at -10 dB and 1.5 GHz at -20 dB. Experimental results showed that the filter is capable of separating two radio frequency (RF) signals spaced as close as 50 MHz without significant distortion. When this demultiplexer was employed to optically separate 2.4 GHz and 900 MHz radio signals, it was found to be linear from -38 dBm to +6 dBm with ~ 25.5 dB isolation. There was no significant increment in the BER of the underlying multimedia data. Results verified that the fabricated narrow bandpass filter can be a potential candidate in demultiplexing of RF signals in networks based on subcarrier multiplexed schemes.


Author(s):  
Uma Nandhini D ◽  
Udhayakumar S ◽  
Latha Tamilselvan ◽  
Silviya Nancy J

<p class="0abstract">Computing with mobile is still in its infancy due to its limitations of computational power, battery lifetime and storage capacity. These limitations hinder the growth of mobile computing, which in-turn affects the growth of computationally intensive applications developed for the mobile devices. So in-order to help execute complex applications within the mobile device, mobile cloud computing (MCC) emerged as a feasible solution. The job of offloading the task to the cloud data center for storage and execution from the mobile seems to gain popularity, however, issues related to network bandwidth, loss of mobile data connectivity, and connection setup does not augment well to extend the benefits offered by MCC. Cloudlet servers filled this gab by assisting the mobile cloud environment as an edge device, offering compute power to the connected devices with high speed wireless LAN connectivity. Implementation constraints of cloudlet faces severe challenges in-terms of its storage, network sharing, and VM provisioning. Moreover, the number of connected devices of the cloudlet and its load conditions vary drastically leading to unexpected bottleneck, in which case the availability to server becomes an issue. Therefore, a scalable cloudlet, Client Aware Scalable Cloudlet (CASC) is proposed with linear regression analysis, predicting the knowledge of expected load conditions for provisioning new virtual machines and to perform resource migration.</p>


Author(s):  
Takuya Hiraguri ◽  
Syun Sakurai ◽  
Koichi Karasawa ◽  
Hidetoshi Nakayama ◽  
Kazuki Ashida ◽  
...  

Metals ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 663
Author(s):  
Liu ◽  
Yu ◽  
Yang ◽  
Zhao ◽  
Zhai

To improve the comprehensive performance of high speed steel (HSS) cold rolls, the induction hardening processes were analyzed by numerical simulation and experimental research. Firstly, a modified martensitic phase transformation (MMPT) model of the tested steel under stress constraints was established. Then, the MMPT model was fed into DEFORM to simulate the induction quenching processes of working rolls based on an orthogonal test design and the optimal dual frequency of the induction quenching process was obtained. The results indicate that the depth of the roll’s hardened layer increases by 32.5% and the axial residual tensile stress also becomes acceptable under the optimized process. This study provides guidance for studying phase transformation laws under stress constraints and the optimization of complex processes in an efficient manner.


2012 ◽  
Vol 591-593 ◽  
pp. 1835-1838
Author(s):  
Xu Hui Cao ◽  
Cai Wu Lu ◽  
Yu Ji Li

WI-FI is currently a popular wireless LAN technology, with access to high speed, large coverage area and so on. WI-FI has its flexibility and mobility, more and more attention, showing great prospects. This article describes the characteristics and advantages of WI-FI technology, combined with the actual situation of a WI-FI based wireless sensor technology and monitoring system for the implementation of the mine ventilation plan, and the program specific application in the monitoring system has been described, the program has proved flexible, simple wiring, has certain application value.


2010 ◽  
Vol 46 (11) ◽  
pp. 800 ◽  
Author(s):  
S.-R. Yoon ◽  
S. Seo ◽  
M.L. Huang ◽  
S.-C. Park

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