Dual band dielectric resonator antenna for wireless application

The proposed technique is an integration of a slot antenna and a dielectric resonator antenna (DRA). This is designed without compromising miniaturisation and efficiency. It is observed that the integration of slot and dielectric structure itself may be merged to achieve extremely wide bandwidth over which the antenna polarisation and radiation pattern are preserved. Here the effect of slot size on the radiation performance of the DRA is studied. The antenna structure is simulated using the CST software. The simulated results are presented and compared with the measured result. This DRA has a gain of 7.1 and 6.3?dBi at 5.7 and 8.1?GHz, respectively, its 10?dB return impedance bandwidth of nearly 4.5% and 5.5% at two resonating frequencies. A total of 98% efficiency has been achieved from the configuration. It is shown that the size of the slot can significantly affect the radiation properties of the DRA and there are good agreements between simulation and measured results.     

Double-slot antennas on extended hemispherical and ellipticalsilicon dielectric lenses

Far-field patterns and Gaussian-beam coupling efficiencies are investigated for a double-slot antenna placed on hemispherical lenses with varying extension lengths. The radiation patterns of a double-slot antenna on a silicon dielectric lens are computed using ray-tracing inside the dielectric lens and electric and magnetic field integration on the spherical dielectric surface. The measured radiation patterns at 246 GHz and Gaussian-beam coupling efficiencies show good agreement with theory. The theoretical results are presented in terms of extension-length/radius and radius/λ, and therefore result in universal design curves for silicon lenses of different diameters and at different frequencies. The theoretical and experimental results indicate that for single units, there exists a wide range of extension lengths which result in high Gaussian-coupling efficiencies (50-60%) to moderately high f 's. These Gaussian-coupling efficiencies can be increased to 80-90°% with the use of a λ_m/4 matching-cap layer. For imaging array applications with high packing densities, an extension-length/radius of 0.38 to 0.39 (depending on frequency) will result in peak directivity and a corresponding Gaussian-coupling efficiency 15-20% lower than for single units     

Ray tracing on extended hemispherical and elliptical silicon dielectric lenses

In this paper, extended hemispherical and elliptical silicon dielectric lenses are compared by means of ray tracing. It is shown that the optical focuses of two lenses are not at same position though the elliptical lens is synthesized from an extended hemispherical lens by carefully choosing a particular extension length as stated in ref[1]. It may be used to explain why the best compromise between alignment, directivity and Gaussian-coupling effciency will be obtained if the feed antenna is placed at the region between 2.2 mm and 2.4 mm of extension length (for 13.7 mm diameter lens, dielectric contant = 11.7).     

Double-slot antennas on extended hemispherical and elliptical quartz dielectric lenses

In this paper, the theoretical far-field patterns and Gaussianbeam coupling efficiencies are investigated for a double-slot antenna placed on quartz hemispherical lenses with varying extension lengths. The radiation patterns of the double-slot antenna are computed using ray-tracing inside the lens and electric and magnetic field integration on the spherical dielectric surface. The theoretical results are equally valid for double-dipole, log-periodic, and spiral antennas, and are presented in extension length/radius and radius/λ. Therefore, the results yield universal design curves for quartz lenses of different diameters and at different frequencies and using different antennas. The results indicate that forsingle units, there exists a wide range of extension lengths (ext. length/radius=0.61 to 0.76) which result in high Gaussian-coupling efficiencies to moderately highf/# systems. Forimaging array applications with high packing densities, an extension length/radius=0.82 to 0.93 (depending on frequency) will result in peak directivity and highest packing density but lower Gaussian-coupling efficiencies.     

Electromagnetic and optical behavior of two classes of dielectric lenses

Two families of spherically symmetric dielectric lenses are considered. Their optical properties are studied, and the radial eigenfunctions describing the electromagnetic field inside the lenses are found in terms of hypergeometric functions. Among the members of these two families are the Luneburg lens, the Maxwell fisheye, the isotropic lens of Eaton, and a lens that behaves like a metal reflector.     

CWDM multi/demultiplexer consisting of stacked dielectric interference filters and off-axis diffractive lenses

A compact coarse wavelength-division multi/demultiplexer based on a stack of dielectric interference filters and an array of off-axis diffractive lenses is reported. The prototype optical system was packaged in the volume of 6.4 (width) /spl times/ 2.5 (height) /spl times/ 8.2 mm (depth). The optical system is interfaced via a multichannel connector with single-mode fiber ribbons. Optical insertion losses are better than 5 dB. The worst channel crosstalk was -19 dB.     

Millimeter wave dielectric loaded exponentially tapered slot antenna array using substrate integrated waveguide for gigabit wireless communications

A new and upcoming application is the use of 60 GHz antennas for high date rate point-to-point connections to serve Gigabit(Gi-Fi)w ireless communications.The design of M illimeter w ave(M m W)antennas has to cope w ith the unadorned influences of manufacturing tolerances and losses at 60 GHz.In this paper,the concept of Substrate Integrated Waveguide(SIW)and Exponentially Tapered Slot(ETS)antenna w ere used together to design a high gain,efficient planar dielectric loaded antenna for M m W Gi-Fi w ireless communications at 60 GHz.The SIW is used to feed the antenna and a dielectric is utilized in front of the antenna to increase the gain.The dielectric loaded ETS antenna and compact SIW feed w ere fabricated on a single substrate,resulting in low cost and easy fabrication.The antenna w ith elliptical shaped dielectric loaded w as fabricated using printed circuit board process.The measured gain of the single element antenna is 10.2 dB,w hile the radiation efficiency of 96.84%is obtained at 60 GHz.The Y-junction SIW pow er divider is used to form a 1×4 array structure.M easured gain of the 1×4 array antenna is 13.3 dB,w hile the measured radiation pattern and gain are almost constant w ithin the w ide bandw idth of the antenna.     

A perturbation and iterative perturbation analysis of linearly chirped grating lenses of medium Q in dielectric waveguides

A perturbation and iterative perturbation analysis of linearly chirped quasi-periodic structures of mediumQfactor in planar dielectric waveguides has been formulated. This analysis can be used to calculate the diffraction efficiency and the angular field of view of a given linearly chirped grating structure, for a specific incident beam including the effect of higher orders of diffractions. The numerical example of aF = 10 , f = 10m.m,Lambda_{min} = 2.06, Lambda_{max} = 4.25and grating groove length = 15 μm is presented.     

Design trades for Rotman lenses

The foundation of a satisfactory Rotman lens design is geometric. The effects of seven design parameters (focal angle, focal ratio, beam angle ratio, maximum beam angle, beam port curve ellipticity, array element spacing, and focal length/λ) on the shape, and on the geometric phase and amplitude errors of a Rotman lens are described. The advantage of beam port shaping to reduce phase error, and of pointing port horns at the opposite apex (instead of normal to the curve) to reduce off-axis beam amplitude asymmetries, are shown numerically. A design procedure for selecting these parameters is given, and a calculation of lens gain is presented     

星载成形反射面天线的设计方法

成形反射面天线的设计与综合是近年来卫星天线发展的一个热点问题 ,本文对日本、北美和欧洲成形反射面天线的技术发展和综合方法作了介绍和比较。     

Optimization of the dielectric layer for electrowetting on dielectric

In this work the minimum actuation voltage V_min for droplet actuation with electrowetting on dielectric (EWOD) is analyzed. At first, the theoretical background of drop transport with EWOD is shown. Then the impact of thin dielectric films deposited with atomic layer deposition (ALD) and super-hydrophobic layers on the minimum required actuation voltage for drop transport are presented. To this, contact angles are measured on both Al₂O₃ and fluorinated DLC each with a drop of water. For verify the hypothesis, the analytically calculated values for the minimum actuation voltage V_min are compared with numerical simulation results using COMSOL Multiphysics^®. The results show that the actuation voltage value from the simulation is lower than calculated analytically.     

Optimized three-dimensional lenses for wide-angle scanning

Three-dimensional bootlace lens antennas with two and four focal points can be optimized to produce high-quality scanned beams over a wide field of view. For two-dimensional scanning, the planar feed locus is replaced by a curved feed locus designed to minimize path length errors. Comparisons with previous bootlace lens designs demonstrate the advantages of this focal distribution. The bifocal lens shows good scanning performance in both principal and orthogonal planes. The quadrufocal lens performs better in its principal plane than in its orthogonal plane. It is also shown that the quadrufocal lens can be realized with a planar outer surface and a circular focal arc, and improved scanning performance is still achievable. Further optimization of the focal arc and/or relaxation of the planar outer surface condition results in quadrufocal lenses with negligible phase errors in the principal plane.     

Bound on Scattering Elements for Irregularly Shaped Waveguides

A lower bound is obtained on the phase shifts that characterize the scattering of electromagnetic waves by obstacles in an irregularly shaped waveguide for which the form function is imprecisely known. A numerical example illustrates the method.     

Complex Shaped On-Wafer Interconnects Modeling for CMOS RFICs

A model development methodology for complex shaped on-wafer interconnects is presented. The equivalent circuit of the entire interconnect is obtained by cascading basic subsegment models. The extracted parameters are formulated into empirical expressions. Thus, the proposed model can be easily incorporated with commercial electronic design automation (EDA) tools. The accuracy of the model is validated by the on-wafer measurements up to 20 GHz.     

SVM for Constellation Shaped 8QAM PON System

Nonlinearity impairments and distortions have been bothering the bandwidth constrained passive optical network(PON)system for a long time and limiting the develop-ment of capacity in the PON system.Unlike other works concentrating on the exploration of the complex equalization algorithm,we investigate the potential of constellation shap-ing joint support vector machine(SVM)classification scheme.At the transmitter side,the 8 quadrature amplitude modulation(8QAM)constellation is shaped into three designs to mitigate the influence of noise and distortions in the PON channel.On the receiver side,simple multi-class linear SVM classifiers are utilized to replace complex equalization methods.Simulation results show that with the bandwidth of 25 GHz and overall bitrate of 50 Gbit/s,at 10 dBm input optical power of a 20 km standard single mode fiber(SSMF),and under a hard-decision forward error correction(FEC)threshold,transmission can be realized by employing Circular(4,4)shaped 8QAM joint SVM classifier at the maximal power budget of 37.5 dB.     

A THz Tomography System for Arbitrarily Shaped Samples

We combine a THz time-domain spectroscopy system with a robotic arm. With this scheme, the THz emitter and receiver can be positioned perpendicular and at defined distance to the sample surface. Our system allows the acquisition of reflection THz tomographic images of samples with an arbitrarily shaped surface.     

无线设备用晶体控制振荡器

晶体控制振荡器主要用于稳定时钟发生器的时间频率,它可为数据处理设备提供时钟信号。因为基于微处理器的设备通常都有内置的计时功能,因此在无线设备中一般应用有晶体控制振荡器。 或许因为晶体控制振荡器普遍应用于无线设备里,通常很少提及振荡器的基本工作原理。本文概括介绍晶体振荡器的设计和特性方面的基本知识,可能对于工程师们在新产品开发过程中采用晶体振荡器能有所帮助。