一种新型三谐振点电容式RF MEMS开关

给出了改进的电容式开关等效电路模型以及基于该电路模型的一种新型的多频段工作的电容式RFM EM S开关的设计和制作研究。分析表明,当开关的上电极为多支撑梁结构时,需要对传统的开关等效电路加以改进。利用新型等效电路模型进行模拟发现,通过适当的参数选择,可以获得多谐振点开关,不仅可以在多个频段适用,并且可以适用于较低频段。设计了一种可工作在X波段下的三谐振点电容式RF MEMS开关,并在高阻硅衬底上采用表面微加工工艺制备了开关样品。三谐振点开关的在片测试结果为:驱动电压为7 V,“开”态的插入损耗为0.69 dB@10.4 GHz,“关”态的隔离度为30.8 dB@10.4 GHz,其微波性能在0~13.5 GH z频段下优于类似结构的传统单谐振点开关。     

Multiresonant Thermally Activated Delayed Fluorescence Emitters Based on Heteroatom‐Doped Nanographenes: Recent Advances and Prospects for Organic Light‐Emitting Diodes

Since the first report in 2015, multiresonant thermally activated delayed fluorescent (MR‐TADF) compounds, a subclass of TADF emitters based on a heteroatom‐doped nanographene material, have come to the fore as attractive hosts as well as emitters for organic light‐emitting diodes (OLEDs). MR‐TADF compounds typically show very narrow‐band emission, high photoluminescence quantum yields, and small ΔE_ST values, typically around 200 meV, coupled with high chemical and thermal stabilities. These materials properties have translated into some of the best reported deep‐blue TADF OLEDs. Here, a detailed review of MR‐TADF compounds and their derivatives reported so far is presented. This review comprehensively documents all MR‐TADF compounds, with a focus on the synthesis, optoelectronic behavior, and OLED performance. In addition, computational approaches are surveyed to accurately model the excited state properties of these compounds.     

Hybrid polarized microstrip antenna for multifrequency application

In this article, a novel single layer, single‐fed ring antenna is analyzed for multiresonance operation in WLAN/Wi‐MAX bands. The antenna geometry consists of a square patch with a dual square ring enclosure which commit multiresonance characteristics. The antenna is excited using electromagnetically from a separate feed patch placed in between the rings. The impedance characteristics are enhanced up to 18% using a unique hourglass type feed patch in between the square rings. The suggested antenna exhibits good return loss at 2.45, 3.5, and 5.8 GHz having bore sight gain response of . Hybrid polarization is comprised with circular polarization and dual‐linear polarization characteristics are investigated in this research work. This antenna was implemented on Arlon's substrate with dielectric constant ?r = 2.55 and substrate thickness h = 1.524 mm. A good axial ratio is achieved with optimized corner truncation.     

Development of Multiresonant ZVS High‐Frequency Inverter

A novel multiresonant zero‐voltage switching (ZVS) high‐frequency inverter has been developed. This inverter is capable of supplying a current of large amplitude to a load as a result of suppression of the main switch current. The principle of the ratio of the main switch current to the load current is theoretically demonstrated using the capacitance ratio. High‐frequency operation with ZVS is verified experimentally.     

A resonance method of measuring the reflection and transmission coefficients of a directional coupler

A method of determining the complex reflection and transmission coefficients is considered, based on measurements of the resonance characteristics of a short-circuited waveguide, excited through an inductive iris. The parameters of the coupler in the R2-54/3 type panoramic VSWR measuring instrument are measured. __________ Translated from Izmeritel’naya Tekhnika, No. 3, pp. 60–64, March, 2007.