Iodine(III)-mediated aromatic amidation vs olefin amidohydroxylation. The amide N-substituent makes the difference

A series of N-methoxy- and N-para-methoxyphenylacetamides simultaneously substituted at the α position by a benzyl and an allyl group have been treated with phenyliodine(III)bis(trifluoroacetate) to generate stabilized N-acylnitrenium intermediates. It has been observed that, when starting from N-methoxy substituted amides, such intermediates are intramolecularly trapped by nucleophilic arene rings to render the quinolinone skeleton. Alternatively, under the same reaction conditions, N-para-methoxyphenylamides afford pyrrolidinone derivatives through an olefin amidohydroxylation process.     

一种小型化多频段天线的研究

针对移动终端小型化多功能的要求,研究了一种小型多频工作的天线。该天线由两部分构成,分别馈电,实现了无线通信中天线的小型化和多频段的要求。对其进行了仿真和测试,结果表明该天线可工作于850MHz、900MHz、1800MHz、1900MHz及2．4GHz 5个频段,覆盖频段较宽,性能较好。     

一种宽带小型化的三频PIFA天线

综合多种技术,提出了一种宽频带小型化的三频PIFA天线。基于缝隙加载技术,在辐射贴片上开双L形槽以形成多个电流路径,从而产生多个谐振频率;引入折叠的辐射片结构以缩小天线的轮廓;通过较宽的馈电带片激励来展开天线各个频段的带宽。天线的仿真与测试结果吻合较好,证实了该新型天线具有较宽的工作频带和良好的辐射特性,能较好地满足GSM/DCS/ISM三个频段的要求,还覆盖了S-DMB频段,具有一定的实用价值。     

一种应用于RFID 的印刷倒F 天线设计

基于平面倒F 天线模型,设计了一种用于2.4GHz RFID 系统的印刷倒F 单极子天线。采用易于射频集成的微带馈电方式,并结合带线阻抗变换,以实现较宽的阻抗带宽;采用在印刷倒F 结构正上方加载寄生辐射贴片,以提高天线增益。利用高频电磁仿真软件Ansoft HFSS 对提出的天线进行了建模、仿真和优化设计,该天线在2.28-2.51GHz 频率 范围内VSWR＜2,达到了10%左右的阻抗带宽,特别在RFID 系统的工作频段内（2.401GHz~2.409GHz）VSWR＜1.35, 增益＞2.36dBi。该天线具有尺寸小,重量轻,成本低等众多优点,能应用于工作于2.4GHz 的各种RFID 系统中。     

Baylis-Hillman acetates in organic synthesis: A simple two-step strategy for oxindole-spiro-α-arylidene-γ-butyrolactone framework

A facile, convenient, and two step strategy for synthesis of spirooxindoles containing α-arylidene-γ-butyrolactone moiety has been developed via monoalkylation of 2-oxindoles with Baylis-Hillman acetates followed by the spirolactonization of the resulting cinnamic esters on treatment with phenyliodine (III) bistrifluoroacetate (PIFA).     

Mutual coupling between identical planar inverted-F antennas

Mutual coupling between two identical planar inverted-F antennas (PIFA) located on an infinite ground plane is studied numerically. Several arrangements of side-by-side, collinear, parallel-in-echelon, and orthogonal PIFA antennas with element spacing varying from $0.06\lambda$ to $1.20\lambda$ are investigated at the design frequency of 1.9 GHz, and in the $-6\mathrm{dB}$ bandwidth between 1.8 and 2.0 GHz. It is found that choosing configurations that maximizes the separation between the open-end of the PIFAs reduces the mutual coupling.     

一种三频带平面倒F手机天线的设计与仿真

实现手机内置天线的小型化和多频带有多种方法。文中采用折叠的方法进一步实现小型化,开双U型槽实现了三频带工作,并设计出一种新型平面倒置F型三频带天线结构。该结构具有设计简单、易于实现的优点,满足了现代无线通信系统对移动终端的要求。v     

手机天线辐射与人头吸收率的仿真分析

利用HFSS软件仿真分析了PIFA手机天线的电磁辐射特性。为改善天线的性能,在原结构基础上添加了金属屏蔽板,研究了加入屏蔽板后天线性能的变化情况。通过HFSS仿真人体头部模型内的电场和整体的SAR分布的方向图,仿真结果表明,加入屏蔽体后人体头部的辐射电场和SAR分布明显减弱。     

High isolation dual-element modified PIFA array for MIMO application

In this paper,we focus on antenna array design for mobile phone with finite volume and propose a novel antenna element structure by capacitive feeding and capacitive loading method based on the planar ...     

PIFA-promoted intramolecular oxidative C(aryl)-H amidation reaction: Synthesis of quinolino[3,4-b]quinoxalin-6(5H)-ones

A facile and direct intramolecular oxidative C(aryl)-H amidation reaction was developed for the synthesis of quinolino[3,4-b]quinoxalin-6(5H)-ones in moderate to excellent yields starting from readily available materials by tethering the adjacent N-methoxyamide and aryl portions in the presence of phenyliodine(III) bis(trifluoroacetate) at room temperature. This metal-free approach is a valuable addition to the traditional methods already available for the preparation of these molecules.