共查询到20条相似文献,搜索用时 15 毫秒
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Khajehnasiri A. Safavi-Naeini S. 《Antennas and Propagation, IEEE Transactions on》2007,55(5):1283-1292
A new approach for multiport network modeling (MNM) of multilayer planar circuits coupled through slots in ground plane is introduced. Generalized network formulation for aperture problems is combined with Okoshi's model for planar circuits to obtain a unified circuit model for two irregularly shaped planar circuits coupled through a slot of arbitrary shape in their common ground plane. The methodology, which can be generalized to structures having more than two layers, is described by applying the method to a two-layer structure. Results for several sample structures will also be presented 相似文献
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M. Mongiardo Prof. Ph.D. P. Russer Univ.-Prof. Dr. techn. 《e & i Elektrotechnik und Informationstechnik》2004,121(1):2-5
Rigorous network representations for radiating structures are still an open problem. In this contribution the concept of Transition Region for deriving such a network representation of complex structures radiating into free-space is introduced. The space is divided into one or more computational domains which contain the complex geometrical features embedded into a transition region delimited by an outer spherical surface. The introduction of the transition region is expedient to avoid a large computational domain of spherical shape. A theoretical investigation of the computational procedures for deriving the transition region network representation is also presented. 相似文献
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为解决采用单个虚拟网特征重配置导致虚拟网接受率低的问题,基于资源竞争特征重构底层网络模型,并基于此构建虚拟网映射线性规划模型。设计了无划分的随机舍入优化算法和有划分的随机舍入优化算法,为每个虚拟网分配全局最优的底层网络资源。与现有算法相比,该算法下虚拟网请求的平均接受率提升11%,节点资源平均利用率提升61%,链路资源平均利用率提升27%。 相似文献
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The use of a medium-voltage (MV) transmission network as a physical medium for communications with the distribution line carrier (DLC) technique may lead to electromagnetic compatibility problems. Computed and experimental results concerning the undesired electromagnetic fields radiated by the DLC are discussed. The NEC-2 code is used to model a network considered as a radiating structure in the 10-100-kHz band and to estimate the average values of undesired radiated electromagnetic fields. An appropriate NEC user interface has been developed on a Macintosh computer in order to model a realistic complex network. Results obtained with NEC are validated through comparisons of simulated fields with measured ones, and satisfactory agreement is found. A numerical parametric study shows the effects of the network configuration on the undesired radiated fields 相似文献
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神经网络在辐射源识别系统中的应用 总被引:1,自引:0,他引:1
作者针对当前辐射源识别系统中存在的问题,提出了一种结合神经网络技术的辐射源识别新方法。该方法可以快速高效地识别各类辐射源,既有基于统计分析的辐射源识别系统的快速性,又有基于专家系统的辐射源识别系统的自适应性和准确性。实际仿真结果表明该方法是有效的。 相似文献
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A network model is presented for the capacitively fed microstrip antenna element. This element consists of a ground plane, a radiating patch and a small patch located between the ground plane and radiating patch. The small patch is fed by a coaxial probe. The capacitive coupling between the patches allows the antenna to be matched. The network model is derived from a rigorous solution. The relationship between the lumped components of the network model and the physical working mechanism of the structure is described 相似文献
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This paper presents a synthesis of linear standingwave arrays of microstrip antennas such as transverse dipoles, series-fed by a proximity coupled microstrip line. Each radiating element is characterized by its self-admittance and mutual coupling admittance. The self-admittance depends on geometrical parameters and on the nature of the substrate, while the mutual coupling admittance is related to the presence of the other radiating elements. These values are computed exactly using an integral equation technique combined with a two-port model of the element. The synthesis procedure is validated with measurements of the radiation pattern and a return loss of a 20-dipole array. The importance of mutual coupling in the design process is clearly demonstrated. 相似文献
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A novel substrate‐integrated waveguide (SIW) cavity‐backed slot antenna is proposed in this study to achieve enhanced‐gain performance. The peak gain is remarkably improved with the use of an SIW cavity and metallic superstrate. The superstrate comprises a single rectangular slot window and two half‐wavelength patches. The gain can be enhanced by combining the in‐phase radiating fields. Further, the 10 dB bandwidth of the proposed antenna ranges from 2.32 GHz to 2.49 GHz, which covers the wireless local area network band. The measured peak gain is 9.44 dBi at 2.42 GHz. 相似文献
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Cerretelli M. Tesi V. Biffi Gentili G. 《Vehicular Technology, IEEE Transactions on》2008,57(3):1398-1403
This paper describes the design of a new compact dual-band roof antenna (which is capable of operating in both U.S. and European mobile telephone bands) for automotive applications. The flipper shape of the antenna and its dimensional constrains are chosen according to prevailing automotive market trends. The chosen basic geometry of the radiating element is a planar printed monopole structured as a vertical fan with two narrow strips folding toward the ground plane and etched on a low-cost, medium-permittivity thin substrate. The geometrical variations of the basic radiating structure are introduced afterward to constrain the antenna shape under the assigned profile and to allow easy integration of a small Global Positioning System patch antenna without affecting radiation and bandwidth performances. The integration of a matching network directly over the etched monopole trace allows a good input matching over the lower and upper operative bands to be obtained, slightly affecting the radiation efficiency of the whole antenna. 相似文献
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Jeong-Geun Kim Hyung Suk Lee Ho-Seon Lee Jun-Bo Yoon Hong S. 《Microwave and Wireless Components Letters, IEEE》2005,15(10):635-637
A 60-GHz coplanar waveguide (CPW)-fed post-supported patch antenna is presented using micromachining technology. In the proposed structure, the radiating patch and the feed line network can be optimized separately with a substrate. The antenna performance is improved by elevating the patch in the air. A patch array antenna is also designed with a simple feed network. The fabricated antenna shows broad band characteristics such as -10 dB bandwidth of 4.3GHz from 58.7GHz to 64.5GHz in the single patch antenna and 8.7GHz from 56.3GHz to 65GHz in 2/spl times/1 patch array antenna. 相似文献
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W波段(75~110 GHz)的电磁波大气吸收率低、波长短、可用频带宽,在雷达、通信等领域应用广泛.文章设计了一种W波段基片集成波导(substrate integrated waveguide,SIW)背腔缝隙天线,-10 dB的阻抗带宽达到28.6%(78.93~105.24 GHz),覆盖了W波段75%的频带范围.天线采用双层基片结构.上层为SIW谐振腔及四条辐射缝隙构成的谐振辐射单元,谐振腔内同时存在TM130与TM310混合模、TM320模以及TM330模三种高次模,和辐射缝隙一起形成多谐特性,实现带宽拓展;底层为通过耦合缝隙馈电的集成波导,易于扩展成平面网络,构建高增益背腔缝隙天线阵列.该天线频带宽、交叉极化低、剖面低、易于与平面微波电路集成、加工成本低,具有良好的应用前景. 相似文献
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An efficient numerical approach to model antennas that include a microstrip element radiating in the presence of material layers is developed. The class of antennas considered is fed through the ground plane by a coaxial transmission line. The reaction integral equation is formulated by treating the coaxial aperture as part of the antenna. The substrate thickness can be arbitrary, making this numerical technique suitable for high-frequency applications. The effects of the substrate are also included in the analysis. Numerical results are obtained for the current distribution and input impedance. The algorithm is validated with experimental results 相似文献
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A novel low-cost antenna design suitable for radio frequency identification (RFID) tags mountable on metallic surfaces is presented. The antenna consists of two shorted patches printed on a lossy FR4 substrate and their radiating edges are facing each other. A tag chip feed is placed between two patches and a stacked shunt capacitor is formed to adjust the antenna impedance. The proposed design reduces the substrate loss and improves the radiation efficiency by more than double compared with a conventional planar inverted-F antenna, which is verified by simulation and measurement. 相似文献
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Isha Pathak Atul Tripathi Deo Prakash Vidyarthi 《International Journal of Communication Systems》2018,31(10)
In a network virtualization environment, a significant research problem is that of virtual network embedding. As the network virtualization system is distributed in nature, an effective solution on how to optimally embed a dynamically generated virtual network request on the substrate networks that are owned and managed by multiple infrastructure providers needs proper attention. The problem is computationally hard, and therefore, many approaches, implying heuristics/meta‐heuristics, have been applied for the same. A meta‐heuristic, Artificial Bee Colony algorithm is getting popular due to its robustness toward complex problem solving. A novel approach based on Artificial Bee Colony to address the dynamic virtual network embedding problem in a multiple infrastructure provider scenario is proposed in this work. Bee population is initialized by using a greedy heuristic in which the number of substrate networks together with virtual network requests constructs a bee. Generated solution, in the population, is improvised by using greedy selection that explores a local search method adopted by the bees. In greedy selection, the new candidate source is memorized by the bee if its fitness is better than the fitness of the existing source. The performance study of the proposed model is done by simulation over various metrics such as embedding cost, embedding time, and acceptance ratio. A comparative study is conducted with other nature‐inspired virtual network embedding algorithms on these metrics. The findings affirm that the proposed virtual network embedding approach performs well and produces better results. 相似文献
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《Microwave Theory and Techniques》2009,57(7):1734-1742