Field Profile Synthesis with an Antenna Array

Two algorithms for the synthesis of a microwave beam with desired characteristics are discussed. The beam is composed by an array of either identical or non-identical antennas. In an example, the application of those algorithms for wireless power transmission is demonstrated.     

地球站天线性能的入网要求及其发展趋势

本文系统总结了地球站天线ＩＮＴＥＬＳＡＴＭ网的最新技术要求，阐述了地球站天线指标的发展趋势，指出了现代卫星通信地球站天线设计研究的方向。     

CORRUGATED CONICAL HORN FOR MULTI-FREQUENCY BAND USE

The theory of corrugated conical horn operating at multi-frequency bands is described,and aprqactical corrugated conical horn is constructed.It can operate at three frequency bands(4,6,11 GHz)atleast.The cross polarization peak level is better than -25 dB at 4,6 GHz frequency bands,and the amplitudepattern at 11 GHz frequency band is also very good.It is shown theoretically and experimentally that thecorrugated conical horn operating at multi-frequency bands is the best condidate for multi-frequency bandfeeds.     

天线性能对被动毫米波探测器信噪比的影响

本文分析了天线增益和电压反射系数幅值对被动毫米波探测器信噪比的影响，并用边馈微带并现列天线做实验测试，实验结果与理论分析相吻合。     

神经网络模型在多模多馈天线设计中的应用

文章采用人工神经网络对多模多馈天线进行建模,并应用于多模多馈天线的分析与设计中。由于神经网络具有精度高,实时调用速度快等优点,因此文章建立的多模多馈天线神经网络设计方法具有准确、可靠、省时及其它辅助设计等优点。文中的仿真结果证明了该方法在多模多馈天线分析设计中的有效性。     

Wide-band nulling system for antenna array based on a photonic microwave filter and optical delay lines

A nulling system for phased array antennas with broad bandwidth and reduced complexity is presented. The system is based on combining the output of an optical beamforming network with an optical transversal filter steered in the angle where a null is desired in a configuration that reduces the number of optoelectronic conversion compared to previous proposals. Preliminary experimental results to show the feasibility of the concept are provided between 2 and 6 GHz, showing null depths of 22, 10 and 19 dB at 2, 5 and 6 GHz, respectively.     

聚合物系统中的传能和光化学

评论了聚合物系统中非辐射能量传递类型,影响能量传递的因素,以及能量传递同聚合物光化学的关系,附22篇文献。     

Biomass Productivities in Wild Type and Pigment Mutant of <Emphasis Type="Italic">Cyclotella</Emphasis> sp. (Diatom)

Microalgae are expected to play a significant role in greenhouse gas mitigation because they can utilize CO₂ from power plant flue gases directly while producing a variety of renewable carbon-neutral biofuels. In order for such a microalgal climate change mitigation strategy to become economically feasible, it will be necessary to significantly improve biomass productivities. One approach to achieve this objective is to reduce, via mutagenesis, the number of light-harvesting pigments, which, according to theory, should significantly improve the light utilization efficiency, primarily by increasing the light intensity at which photosynthesis saturates (I _s). Employing chemical (ethylmethylsulfonate) and UV mutagenesis of a wild-type strain of the diatom Cyclotella, approximately 10,000 pigment mutants were generated, and two of the most promising ones (CM1 and CM1-1) were subjected to further testing in both laboratory cultures and outdoor ponds. Measurements of photosynthetic oxygen production rates as a function of light intensity (i.e., P–I curves) of samples taken from laboratory batch cultures during the exponential and linear growth phase indicated that the light intensity at which photosynthesis saturates (I _s) was two to three times greater in the pigment mutant CM1-1 than in the wild type, i.e., 355–443 versus 116–169 μmol/m² s, respectively. While theory, i.e., the Bush equation, predicts that such a significant gain in I _s should increase light utilization efficiencies and thus biomass productivities, particularly at high light intensities, no improvements in biomass productivities were observed in either semi-continuous laboratory cultures or outdoor ponds. In fact, the maximum biomass productivity in semi-continuous laboratory culture was always greater in the wild type than in the mutant, namely 883 versus 725 mg/L day, respectively, at low light intensity (200 μmol/m² s) and 1,229 versus 1,043 mg/L day, respectively, at high light intensity (1,000 μmol/m² s). Similarly, the biomass productivities measured in outdoor ponds were significantly lower for the mutant than for the wild type. Given that these mutants have not been completely characterized in these initial studies, the exact reasons for their poor performance are not known. Most likely, it is possible that the mutation procedure affected other photosynthetic or metabolic processes. This hypothesis was partially validated by the observation that the pigment mutant had a longer lag period following inoculation, a lower maximum specific growth rate, and poorer stability than the wild type.     

A NEW DESIGN METHODOLOGY FOR PRINTED LOG-PERIODIC MONOPOLE ANTENNA

In theory, Log-Periodic Antenna (LPA) is a linearly polarized antenna with frequency independent properties on the input impedance and gain patterns. Owing to these characteristics, LPA has gained research interests and been employed for many wideband applications. A Printed Log- Periodic Dipole Antenna (PLPDA) with multiple notched bands is proposed for Ultra-WideBand (UWB) applications. An antenna with the notched frequencies of 1.03 GHz, 1.28 GHz, 1.72 GHz, 2.24 GHz and 2.51 GHz is designed, fabricated, and measured. An antenna model was established on the substrate of FR4 and feed by a stripline. The simulation results show that the antenna can achieve an impendence wide bandwidth from 0.89 to 2.58 GHz with return loss less than –10 dB and exhibit stable antenna gain. Furthermore, the measurement result is better consistent with simulation result.     

一种工作在W波段的角锥喇叭天线

本文提出了一种工作在W波段的角锥喇叭天线,天线采用矩形波导馈电。采用电磁场仿真软件Ansoft HFSS 11对所设计的天线进行仿真,结果表明该天线在75GHz～110GHz范围以内具有回波损耗优于-20dB,增益大于20dB的良好特性。天线具有宽频带,低旁瓣,结构简单的优点,在目标识别成像、隐身与反隐身、遥测遥感、地下目标探测以及短距离高速无线通信等领域具有广泛的应用。