Design of multiband PIFA with low SAR value for all commercial mobile communication bands

A low profile planar inverted‐F antenna is proposed for mobile handset applications. Thus, our target is to introduce a new antenna that supports both services, the proposed antenna have broadband characteristic which includes all commercial service bands, GSM850/GSM900/GPS/GSM1800/GSM1900/WCDMA2100/802.11b/g/LTE2600 (824–2690 MHz) as well as 802.11a/n (5150–5825 MHz). Overall size of the antenna is 21 × 45 × 8 mm³ is well suited for mobile handsets due to its low profile, small size, wide bandwidth, the radiation patterns are satisfactorily omnidirectional across the antenna's operation bands, and good gain (the gain in some frequency bands is higher than 4 dBi). The antenna not only has a compact size, but also it supports a low specific absorption rate (SAR) radiation at all the operating frequencies. In addition, the proposed antenna is assessed using the finite difference time domain (FDTD) program written with MATLAB to validate the results. The antenna meets three challenging parameters: the compact size, the multiband operation including the low frequency bands, and the low SAR radiation. The measured results exhibit good agreement with the simulation results from CST and the FDTD program written with MATLAB. As a result, the designed antenna is suitable for small mobile devices and slim wireless applications. © 2014 Wiley Periodicals, Inc. Int J RF and Microwave CAE 25:194–201, 2015.     

A compact planar inverted‐F antenna with U‐shaped strip for all‐metal‐shell handset application

A compact dual‐band planar inverted‐F antenna (PIFA) with U‐shaped strip is proposed in this work for all‐metal‐shell mobile telephone application. As metal‐shell handsets are getting more and more popular nowadays, it raises a big challenge in antenna design as the metal‐shell associated with surrounding electronic components like front‐back‐cameras and telephone receiver would affect the antenna performance. This work provides an optional solution to alleviate this problem, where the metal shell of the handset and a U‐shaped strip are utilized as part of the antenna. The proposed antenna is able to generate radiation at 2.4 GHz for Wi‐Fi application with the help of the metal shell while using the U‐shaped strip can achieve a resonance at 1.575 GHz for GPS application. A prototype has been fabricated to verify the radiation performance in a practical handset test environment.     

Ionic current rectification in a conical nanofluidic field effect transistor

A conical nanofluidic field effect transistor (FET) refers to a conical nanopore embedded with an electrically controllable gate electrode. The surface potential of the nanopore can be effectively regulated by manipulating the gate potential applied to the gate electrode, which in turn controls the ionic current through the nanopore. The field effect on the ionic current rectification (ICR) in the conical nanofluidic FET is comprehensively investigated using a continuum model, composed of Nernst-Planck equations for the ionic concentrations, Poisson equation for the electric potential, and Navier-Stokes equations for the flow field. Under the conditions of a low ionic concentration, a low surface charge density of the nanopore, and a high permittivity of the dielectric nanopore, regulation of ICR by FET is significant. The field effect on the ICR with the gate electrode located in the middle region is opposite to that with the gate electrode located near the tip of the nanopore.     

Design of ultrawide band planar inverted‐F antenna with slotted broad feed

This article presents a low ‐ profile planar inverted‐F antenna (PIFA) for broadband applications. The proposed antenna geometry is simple and does not use any parasitic elements, which makes its fabrication easier. The antenna's radiator is composed of a top loading plate, broad feed plate, and a shorting plate; occupies a total volume of (L × W × H ) 20 × 12 × 6 mm³. The proposed antenna design achieved the wideband characteristics by using the method of bringing resonances to proximity; furthermore, the low ‐ profile feature is achieved by removing some portion of the ground plane according to the volume ratio of PIFA. To validate the simulated results, an antenna prototype has been fabricated. The simulated and measured radiation patterns, gain, group delay, and simulated peak ‐ specific absorption rate (SAR) are presented. The measurement result demonstrates that the proposed antenna design achieved the maximum bandwidth of 142% (3.1–18.5 GHz) for |S ₁₁| ≤ ?10 dB.     

Design of hexa‐band planar inverted‐F antenna using hybrid BSO‐NM algorithm for mobile phone communications

This article presents a new design of multiband planar inverted‐F antenna with slotted ground plane and S‐etched slot on the radiation patch. The proposed antenna is optimized using an efficient global hybrid optimization method combining bacterial swarm optimization and Nelder‐Mead (BSO‐NM) algorithm to cover a very important six service bands including GSM900, GPS1575, DCS1800, PCS1900, ISM2450, and 4G5000 MHz with enhanced bandwidths. The BSO‐NM algorithm in Matlab code is linked to the CST Microwave studio software to simulate the antenna. To validate the results, the antenna is analyzed using the finite difference time domain (FDTD) method. A good agreement is achieved between the results of EM simulation and that produced from the FDTD method. © 2012 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2013.     

A compact multi‐band multi‐input multi‐output antenna for 4G/5G and IoT devices using theory of characteristic modes

A compact four element multi‐band multi‐input multi‐output (MIMO) antenna system for 4G/5G and IoT applications is presented in this paper. The proposed antenna is developed using the theory of characteristic modes helping in systematic design of MIMO antenna system. It consists of four L‐shaped planar inverted‐F antenna (PIFA) elements each operating at 3.5, 12.5, and 17 GHz bands with the bandwidth of 359 MHz, 1 GHz, and more than 3.7 GHz, respectively. The proposed antenna system is suitable for both 4G/5G and internet of things devices as it shows the satisfactory MIMO system performance. Good isolation characteristics are observed by implementing complimentary Metamaterial structure on the ground plane resulting in isolation level lower than ?21 dB between the antenna elements. The proposed antenna is fabricated and experimental results are also presented and discussed.     

Space mapping optimization of handset antennas considering EM effects of mobile phone components and human body

To meet antenna design specifications under realistic conditions, electromagnetic coupling effects between the antenna and its environment must be considered. In this work, an efficient antenna design optimization methodology that considers the influence of the human head and main mobile handset components on the antenna performance is presented. The computational optimization time is dramatically reduced by exploiting a Broyden‐based input space mapping (SM) algorithm. Both coarse and fine models required for the SM algorithm are based on the finite‐element method and are implemented in the same simulator; simplifying the modeling process. However, our coarse model does not consider any object of the actual operational environment. In spite of that and other simplifications applied to the coarse model, the proposed optimization scheme is able to find a solution that meets the specifications in a realistic environment by performing an extremely small number of expensive fine model simulations. Our practical illustration opens up the feasibility of using this CAD methodology to optimize other RF devices that operate in close proximity to objects that affect its desired response, as it is the case for many wearable devices. © 2015 Wiley Periodicals, Inc. Int J RF and Microwave CAE 26:121–128, 2016.     

A novel tree‐shaped antenna with wideband and end‐fire properties designed by competitive algorithm of simulating natural tree growth

This article presents a novel tree‐shaped antenna with wideband and end‐fire properties designed by the Competitive Algorithm of Simulating Natural Tree Growth. The antenna has an impedance bandwidth of 27.2% for S11 < ?10dB, maintains end‐fire radiation pattern and achieves a high gain over the entire frequency band from 5.4 GHz to 7.1 GHz. © 2010 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2010.     

A study on bandwidth enhancement of 900/1800 dual band LTCC chip antenna by using equivalent circuit analysis

In this article, low temperature cofired ceramic (LTCC) technology was used to realize the quarter of wavelength helical antenna instead of the quarter of wavelength monopole for achieving minimization of ceramic chip antenna (13 mm × 5.25 mm × 1.2 mm). The equivalent circuit of the helix‐monopoles combination of chip antenna has been established successfully. Using circuit simulation on the equivalent circuit model we proposed, two extra parasitic monopole antennas were added into helix antenna to enhance the second mode bandwidth because of the presence of these two close modes. The measured performance of the dual band LTCC chip antenna with helix‐three monopoles has been successfully predicted by using circuit simulation instead of EM simulation. The first and the second modes bandwidth of the dual band chip antenna can be achieved to 95 MHz (880–975 MHz) (meeting GSM band) and 300MHz (covering DCS and PCS band), respectively. The measured peak gains of this ceramic chip antenna are approximately ?1.8 dB in low band and 0.6 dB in high band based on the 120 × 40 mm² ground size. © 2008 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2009.     

A high gain tree‐shaped array antenna designed by competitive algorithm of simulating natural tree growth

This article presents a novel 16‐element array antenna designed by Competitive Algorithm of Simulating Natural Tree Growth. The array antenna has an impedance bandwidth ranging from 5.5 to 6.2 GHz for S₁₁ 相似文献   

Giant magnetoimpedance effect of multilayered structure(F/SiO_2)_3/Ag/(SiO_2/F)_3 films deposited in a longitudinal magnetic field

The soft magnetic properties and giant magnetoimpedance(GMI) effect of the multilayered structure(F/SiO2)3/Ag/(SiO2/F)3(F≡Fe71.5Cu1Cr2.5V4Si12B9) films,which were prepared by radio frequency sputtering without and with a longitudinal magnetic field of about 72 kA/m,are studied.The results show that the GMI effect almost cannot be detected in the samples deposited without field,whereas,a longitudinal magnetic field applied during deposition process obviously optimizes the soft magnetic properties of the film...     

A cross‐cultural study of the effect of a graph‐oriented computer‐assisted project‐based learning environment on middle school students' science knowledge and argumentation skills

The purpose of this mixed‐methods study was to explore how seventh graders in a suburban school in the United States and sixth graders in an urban school in Taiwan developed argumentation skills and science knowledge in a project‐based learning environment that incorporated a graph‐oriented, computer‐assisted application (GOCAA). A total of 42 students comprised the treatment condition and were engaged in a project‐based learning environment that incorporated a GOCAA. Of these 42 students, 21 were located in the United States and 21 were located in Taiwan. A total of 26 students comprised the control condition and were engaged in a project‐based learning environment without the GOCAA. Of these 26 students, 15 were in the United States and 11 were in Taiwan. In each country, verbal collaborative argumentation was recorded and the students' post‐essays were collected. A one‐way analysis of variance (ANOVA) was conducted for each measure of science knowledge about alternative energies. The results showed a significant treatment effect for the outcome of scientific explanation among U.S. students, while among Taiwanese students, a significant treatment effect on scientific facts was observed. A one‐way ANOVA was additionally conducted for each measure of argumentation skills and a significant treatment effect on counterarguments and rebuttals was observed among the U.S. students, while in Taiwan, a significant treatment effect on reasoning and rebuttals was observed. A qualitative analysis was conducted to examine how the GOCAA supported students' development of argumentation skills in different countries. This study found distinct argumentation patterns between the U.S. and Taiwanese intervention teams. Additionally, a distinct gender difference in the use of evidence and division of labour was noted when the Taiwanese teams were compared with the U.S. teams, which may be explained by cultural differences. This study concluded that, in both the United States and Taiwan, a project‐based learning environment incorporating a GOCAA was effective in improving students' science knowledge and developing their scientific argumentation skills.