Planar Design Research Articles

Mitigating Indoor Channels With Quad-Polarization Diversity

In this letter, we evaluate the performance of a reconfigurable, planar antenna design to mitigate frequency-selective, multipath fading. Prior work has shown that the diversity provided by two or three polarizations can significantly improve system performance. The considered antenna enables four distinct polarizations, two linear that are mutually orthogonal and two circular that are likewise. Measured 1% diversity gains in a reverberation chamber and in an office were 14 and 11.7 dB, respectively. While the linear and circular configurations are not uncorrelated, these gains are $\sim$ 4 dB greater than gains obtained by selecting between either two orthogonal polarizations. An empirical, geometry-based stochastic channel model is also presented to facilitate further study of polarization diversity in such environments.

New symmetric and planar designs of reversible full-adders/subtractors in quantum-dot cellular automata

Quantum-dot Cellular Automata (QCA) is one of the emerging nanotechnologies, promising alternative to CMOS technology due to faster speed, smaller size, lower power consumption, higher scale integration and higher switching frequency. Also, power dissipation is the main limitation of all the nano electronics design techniques including the QCA. Researchers have proposed the various mechanisms to limit this problem. Among them, reversible computing is considered as the reliable solution to lower the power dissipation. On the other hand, adders are fundamental circuits for most digital systems. In this paper, Innovation is divided to three sections. In the first section, a method for converting irreversible functions to a reversible one is presented. This method has advantages such as: converting of irreversible functions to reversible one directly and as optimal. So, in this method, sub-optimal methods of using of conventional reversible blocks such as Toffoli and Fredkin are not used, having of minimum number of garbage outputs and so on. Then, Using the method, two new symmetric and planar designs of reversible full-adders are presented. In the second section, a new symmetric, planar and fault tolerant five-input majority gate is proposed. Based on the designed gate, a reversible full-adder are presented. Also, for this gate, a fault-tolerant analysis is proposed. And in the third section, three new 8-bit reversible full-adder/subtractors are designed based on full-adders/subtractors proposed in the second section. The results are indicative of the outperformance of the proposed designs in comparison to the best available ones in terms of area, complexity, delay, reversible/irreversible layout, and also in logic level in terms of garbage outputs, control inputs, number of majority and NOT gates.

A Multiphysics Design and Optimization Method for Air-Core Planar Transformers in High-Frequency LLC Resonant Converters

Air-core planar transformers are attractive alternatives to ferrite-core transformers for high-frequency power converters, such as LLC resonant converters. Although many design methods have been proposed for LLC converters, most of them are based on traditional ferrite-core transformers. There is a lack of efficient methods to design and optimize air-core planar transformers for high-frequency LLC converters. This paper presents a multiphysics optimal design framework that combines multiple physical models, the progressive bisection design method, and the Bayesian optimization technique to address air-core planar transformer design issues. It has the following contributions. 1) Multiple physical models, including circuit model, magnetoquasistatic model, full-wave electromagnetic model, are built for transformer design and efficiency evaluation. 2) The progressive bisection method and Bayesian optimization algorithm are applied to accelerate the optimal design process. 3) The proposed framework can accurately and efficiently design optimal air-core planar transformers and optimize efficiency in LLC converters. 4) A high-frequency flexible and thin LLC converter is constructed using the optimal design method.

Optical Metasurfaces for Designing Planar Cassegrain-Schwarzschild Objectives

Reflective objectives are widely used in many imaging systems, but can hardly be compact, due to their curved mirrors. To address this problem, the authors planarize the mirrors in a Cassegrain-style objective by substituting geometric-phase-based flat metasurfaces for conventional curved mirrors. These reflective metasurface objectives are intrinsically free of residual light, and thus less demanding in terms of precision in illumination and nanofabrication, compared to refractive metalenses. This planar metasurface design can potentially reshape and simplify the core components of many microscopes and telescopes, and opens an avenue to ultracompact optics.

Frequency-tunable high-Q superconducting resonators via wireless control of nonlinear kinetic inductance

Frequency-tunable microwave resonators are in great demand especially in hybrid systems where precise frequency alignment of resonances is required. Here, we present frequency-tunable high-Q superconducting resonators fabricated from thin niobium nitride and niobium titanium nitride films. The resonant frequency is tuned by applying a magnetic field perpendicular to the hole structures in the resonator's inductor wire, whose kinetic inductance is modified by wirelessly induced DC supercurrents. A continuous in situ frequency tuning of over 300 MHz is achieved for a 10 GHz resonator with a moderate magnetic field of 1.2 mT. The planar resonator design and the noncontact tuning scheme greatly ease the fabrication complexity and can be widely applied in many hybrid systems for coupling microwave modes with other forms of excitations such as optical photons, phonons, magnons, and spins.

Design of planar and wideangle resonant color absorbers for applications in the visible spectrum

We propose a design approach for color absorbers based on a tri-layer metal-dielectric-metal (MDM) planar geometry, which maintains the same color absorbed, over a range of incident angles from 0° to 80° for light with TM polarization. The dielectrics are chosen to satisfy the ideal conditions of resonance. We calculate the ideal thickness of each dielectric layer by using the planar resonance theory. The numerical results show a total absorption above 85% for all colors of the absorber. We analyzed the influence of the of the metallic top layer thickness and we demonstrated the fabrication error tolerance of the proposed absorber. Finally, we present and discuss the physical mechanisms for the coupling of the electromagnetic field and the absorbed optical power in the structure.

(Invited) Cavity-Free Micro Thermoelectric Energy Harvester with Si Nanowires

Forthcoming trillion-sensors-network society demands the maturity of energy harvesting technology. Among various energy harvesting devices, thermoelectric generator (TEG), which utilizes the Seebeck effect of semiconductors, is anticipated as an ultimate one because it has a potential to provide a semipermanent power from almost unlimited heat energies. In a TEG, the efficiency of energy conversion from heat to electricity is determined by the thermoelectric figure of merit, ZT= S2σT/κ of the employed semiconductor, where S is the Seebeck coefficient, σ the electrical conductivity, κ the thermal conductivity, and T the average temperature between heat source and cold sink. Although higher ZT is favorable to achieve high conversion efficiency, only limited materials were known to have high ZT near the room temperature. Recently, silicon nanowires (Si-NWs) emerged as a promising thermoelectric material; the thermal conductivity of Si-NW was found to decrease drastically as the nanowire is thinned. [1,2] Since then, a number of fabrication examples of Si-based TEG has been reported. [3-5] Conventional demonstrations of planar type Si-based TEG employed long Si-NWs about 10-100 μm which were suspended on a cavity to avoid the bypass of the heat current, as shown in Fig 1a. The authors’ group proposed a new design of planar and short Si-NW TEG, which is illustrated as Fig. 1b. [6-9] Our proposed device is driven by a steep temperature gradient exuding around a heat flow perpendicular to the substrate, and the nanowires are not suspended on a cavity. Furthermore, the power density is scalable by shortening Si-NW to sub-μm length; the areal power generation density is inversely proportional to the square of the NW length. It has been experimentally confirmed that the thermoelectric power was enhanced by shortening the nanowire, and tens of µW/cm2-class power generation was achieved [6,7]. Fig. 2 shows an experimental Si-NW TEG fabricated on a silicon-on-insulator (SOI) wafer by the conventional CMOS process. The SOI layer was patterned into Si-NWs by ArF immersion lithography and reactive-ion etching. Both ends of Si-NW bundle are connected to Si-pads. Al/TiN/Ti electrode was deposited on the Si-pad. We prepared samples with different base Si-substrate thickness, by thinning with backside grinding. The hot side electrode was heated by a custom-made micro thermostat, and the base stage was maintained at room temperature by a water chiller. Fig. 3 shows the thermoelectric power density versus loading voltage curves, measured under an applied external temperature difference of 5 K. The measured power output is normalized by the area of the product of twice of the NW length and the NW pitch, supposing that the pads and NW arrays have a same footprint. The maximum power is obtained in the shortest NW device with 0.25 µm long. The thermoelectic power was drastically enhanced by reducing the Si-substrate thickness. Fig. 4 shows the dependence of the power density on the Si-substrate thickness. The power density of a sample with 50 µm thick Si-substrate reached 12 µW/cm2. The enhancement can be attributed to the increased temperature difference across Si-NWs by suppression of the series thermal resistance at the Si-substrate. Further improvement of thermoelectic power is expected by suppressing the thermal resistance at the Si-substrate. The temperature difference across Si-NW is expected to increase by partially replacing the Si substrate underneath the cold side edge of SiNW with Cu with higher thermal conductivity. According to our finite-element-simulation, [10] however, not only beneath the cold side edge of SiNW, replacing the whole substrate by Cu is the most effective way to improve the power generation density (Fig. 5). The results show that the thermal resistance of the entire substrate should be suppressed as a matter of first priority.

EM lens design using thin planar metasurfaces for high antenna gain and low SLL applications

A novel electromagnetic (EM) lens with high gain, suppressed side-lobe level (SLL) and low profile is designed using thin planar metasurfaces. The proposed design consists of a source patch antenna and an EM lens based on two thin planar metasurfaces. The two thin metasurfaces with an air gap are placed at the focal distance H of about λ /2.25 above the source patch antenna. This configuration forms a thin planar lens in which the source patch antenna emitted quasi-spherical wave in order to transform into plane wave. The total size of source antenna and an EM lens is same. The miniaturised EM lens antenna faces high SLL, which can be reduced by maintaining the uniform transmission phase coefficient and tunable transmission amplitude coefficient of metasurface unit cells. By implementing this topology on metasurfaces, the SLL of the proposed EM lens can be reduced without affecting the boresight gain of source patch antenna. The measured results of the proposed EM lens achieve 7 dB gain enhancement at designed frequency (5.8 GHz) with the SLL suppression of -24 dB. The total volume of planar lens antenna is 1.17 λ × 1.17 λ × λ /2.25 mm 3 , which is very compact compared with other reported planar lens designs.

Effect of natrium sulphate concentration on indoor lights photovoltaic performance

One of the electron suppliers in a indoor lights photovoltaic system is the Na2SO4 electrolyte system. The aim of this research is to know the effect of sodium sulfate concentration on photovoltaic performance of indoor lights photovoltaic. The method used is liquid electrolyte system and gel electrolyte system made with various concentration on planar photovoltaic cell design using Cu2O/Al electrode plate. The ability of the Photoreactor is evaluated to obtain the characteristic curve of I-V at each Na2SO4 concentration. The average daily average power produced at concentrations of 0.25 M (gel), 0.5 M (gel), 0.75 M (solution), and 1 M (solution) were 14.218 μwatt, 6.688 μwatt, 38.334 μwatt, and 23.715 μwatt, respectively. The electrode plate used thin plate Cu2O/Al is 0.00246804 m2. The most optimum indoor lights planar photo-reactor is at a concentration of 0.75 M, with a daily average power performance for each square meter of 15.532 mWatt. Maximum power produced Photoreactor is achieved at a concentration of 1 M, ie 37.83245 mwatt/m2.

Dielectrophoretic cell trapping for improved surface plasmon resonance imaging sensing.

The performance of conventional surface plasmon resonance (SPR) biosensors can be limited by the diffusion of the target analyte to the sensor surface. This work presents an SPR biosensor that incorporates an active mass-transport mechanism based on dielectrophoresis and electroosmotic flow to enhance analyte transport to the sensor surface and reduce the time required for detection. Both these phenomena rely on the generation of AC electric fields that can be tailored by shaping the electrodes that also serve as the SPR sensing areas. Numerical simulations of electric field distribution and microparticle trajectories were performed to choose an optimal electrode design. The proposed design improves on previous work combining SPR with DEP by using face-to-face electrodes, rather than a planar interdigitated design. Two different top-bottom electrode designs were experimentally tested to concentrate firstly latex beads and secondly biological cells onto the SPR sensing area. SPR measurements were then performed by varying the target concentrations. The electrohydrodynamic flow enabled efficient concentration of small objects (3 μm beads, yeasts) onto the SPR sensing area, which resulted in an order of magnitude increased SPR response. Negative dielectrophoresis was also used to concentrate HEK293 cells onto the metal electrodes surrounded by insulating areas, where the SPR response was improved by one order of magnitude.

Design and fabrication of large-sized planar oxygen transport membrane components for direct integration in oxy-combustion processes

Membrane-based oxy-combustion is a promising technology for energy efficient combustion of carbon-containing fuels with the simultaneous opportunity to capture CO2 from the resulting exhaust gas. However, oxy-combustion conditions result in special demands on the design of the ceramic membrane components due to the high pressure and temperature applied. Therefore, we have developed a planar membrane design for 4-end operation using asymmetric membranes of La0.6Sr0.4Co0.2Fe0.8O3−δ. FEM and CFD simulations have been performed in order to develop an internal channel structure that allows withstanding pressures of 5 bar on the feed side while achieving the desired O2 concentrations of 27% in the sweep gas, i.e. CO2, and an oxygen recovery rate from the feed gas of 86% at the same time.Due to the symmetric design of the membrane components, they are scalable and adaptable in size. This design has been realized in a process chain from powder to the final component consisting of thin 20 µm Membrane layer, support with 38% porosity, an inner channelled architecture and a thin (3–5 µm) porous activation layer. Particular emphasis was laid on scalable manufacturing processes in order to ensure transferability to industrial scale. The process chain is also applicable to other membrane materials suitable for any application of interest. Finally, the reproducible processing was successfully demonstrated by the fabrication of membrane components in lengths of 100 mm and widths of 70 mm.

Topological plasmonic edge states in a planar array of metallic nanoparticles

Abstract Photonic topological insulators (PTIs) are electromagnetic structures with highly robust unidirectional edge states, originating from their nontrivial bulk band topology. Here, we propose a plasmonic PTI that supports highly confined one-way edge states capable of transporting deep subwavelength optical frequency plasmons through arbitrary paths without back-scattering. The structure consists of a simple planar array of coupled plasmonic nanoparticles arranged in a perturbed honeycomb lattice that exhibits nontrivial band topology. The operation frequency of the emergent edge states is shown to be independent of the lattice constant, allowing for the miniaturization of the structure. As a high-frequency PTI with a simple and planar design, this structure is compatible with well-established integrated nanofabrication technologies and may find application in planar, compact, and topologically robust integrated nanophotonic devices.

Bismuth-based metamaterials: from narrowband reflective color filter to extremely broadband near perfect absorber

Abstract In recent years, sub-wavelength metamaterials-based light perfect absorbers have been the subject of many studies. The most frequently utilized absorber configuration is based on nanostructured plasmonic metals. However, two main drawbacks were raised for this design architecture. One is the fabrication complexity and large scale incompatibility of these nano units. The other one is the inherent limitation of these common metals which mostly operate in the visible frequency range. Recently, strong interference effects in lithography-free planar multilayer designs have been proposed as a solution for tackling these drawbacks. In this paper, we reveal the extraordinary potential of bismuth (Bi) metal in achieving light perfect absorption in a planar design through a broad wavelength regime. For this aim, we adopted a modeling approach based on the transfer matrix method (TMM) to find the ideal conditions for light perfect absorption. According to the findings of our modeling and numerical simulations, it was demonstrated that the use of Bi in the metal-insulator-metal-insulator (MIMI) configuration can simultaneously provide two distinct functionalities; a narrow near unity reflection response and an ultra-broadband near perfect absorption. The reflection behavior can be employed to realize additive color filters in the visible range, while the ultra-broadband absorption response of the design can fully harvest solar irradiation in the visible and near infrared (NIR) ranges. The findings of this paper demonstrate the extraordinary potential of Bi metal for the design of deep sub-wavelength optical devices.

Quantitative analysis of segmented planar imaging quality based on hierarchical multistage sampling lens array.

Segmented Planar Imaging is an advanced technology for ultra-thin, high-resolution imaging with photonic integrated circuit (PIC). In this paper, a segmented planar imager with a novel hierarchical multistage sampling lens array is proposed, which can effectively improve the sampling of low and medium frequency information. Based on the novel lens array architecture, a full-chain signal level model of the segmented planar imaging system is established, considering the fill factor of lens array and the wavelength spacing of the arrayed waveguide grating in PICs. The simulation results show that the imaging quality of the segmented planar imaging system with the hierarchical multi-level sampling lens array is significantly improved, compared with the original segmented planar imaging system. Moreover, the error range and optimization options of some parameters are given based on the full-chain modeling. There is almost no influence on the system imaging results when the error of the lens array fill factor is within 5%. The imaging quality of the system is enhanced as the wavelength spacing of the arrayed waveguide grating is reduced, and arrayed waveguide grating with wavelength spacing of 10 nm is the optimal choice for the system. The results will be helpful for the optimal design of segmented planar integrated optical imaging systems.

60 GHz square open‐loop resonator (SOLR) based on planar Goubau line (PGL) technology

This study presents the design, fabrication, and measurement of a square open-loop resonator (SOLR) on high resistivity silicon substrate feed with a planar Goubau line (PGL), which is a very low-loss transmission line around 60 GHz fabricated through a very simple and low-cost process. Electromagnetic simulations using ANSYS high frequency structure simulator are performed for the PGL structure, in order to determine the PGL characteristics (impedance, losses and quality factor) versus the line width. The geometrical parameters of the SOLR structure are studied to observe their impact on reflection and transmission properties. An equivalent lumped element circuit is extracted from the distributed planar design to study and optimise the resonating structure using Advanced Design System. This electrical circuit response is successfully compared to the planar electromagnetic structure one, and a parametric study permits to better understand the role of the different circuit elements. Field displays lead to a better understanding of the SOLR behaviour. For measurement purpose of the fabricated structure, a coplanar waveguide-PGL transition is optimised with 0.9 dB losses. Simulation and measurement results show good performances for filter applications with 1 dB losses and small size at 60 GHz for 10% bandwidth.

Compact Ridge Waveguide Gysel Combiners for High-Power Applications

This paper presents, to the best of the authors’ knowledge, the first realizations of the Gysel-type power combiner/divider in ridge waveguide technology with two different configurations. Gysel combiners exhibit wider bandwidths than traditional combiners, while offering compact designs when implemented in ridge waveguide, compared with traditional waveguide combiners. In addition, Gysel combiners provide relaxed requirements on the power handling capability of the terminating loads in the case of fault conditions, which may result from imbalance between different inputs. The ridge waveguide designs offer better power handling capabilities, especially in comparison with planar designs. These advantages are shown with two different realizations, in top–bottom and side-by-side configurations, exhibiting very wide bandwidths while occupying very compact volumes. These two designs have been simulated, fabricated, and tested. Excellent test results have been obtained, confirming the validity of the concept.

Incoherent Synthesis of Sparse Arrays for Frequency-Invariant Beamforming

Frequency-invariant beamformers are used to prevent signal waveform distortions in real world applications like audio, underwater acoustics, and radar. Most of existing methods assume uniform arrays, and only few consider sparse designs, which may lead to higher performance in terms of robustness and directivity factor. We propose an incoherent approach that first determines for each frequency bin a sparse set of sensors positions. Subsequently, by using tools of dimensionality reduction and clustering, these selections are merged together yielding the optimal sensors on a sparse array layout. We present design examples of sparse linear and planar superdirective array designs. We show that the proposed incoherent sparse design obtains superior performance in terms of white noise gain, directivity factor, and computational load compared to a uniform array design and compared to a coherent sparse approach, where the sensors’ locations and the beamformer coefficients are optimized simultaneously for all frequencies.

Ka밴드 평면형 능동위상배열 안테나장치 설계

본 논문에서는 항공용 소형 레이다나 유도 무기 탐색기 등에 적용이 가능한 Ka대역 평면형 능동 위상배열 안테나장치를 설계한 내용을 설명하였다. 본 안테나장치는 1000개 급의 복사소자 면배열로 구성하고, 직경 200mm 이내의 크기로 설계하였다. 빔 조향 범위는 ±55° 이상 가능하도록 빔패턴 분석을 통하여 복사 소자 간격을 정의하고 안테나 성능 분석을 수행하였다. RF 구성품 설계와 버짓 검증을 통해 안테나장치의 송신 EIRP는 94.22 dBm, 수신 G/T는 1.68 dB/k 성능으로 요구 규격을 만족할 수 있음을 확인하였다. 송신 EIRP 규격을 만족하기 위해 TRM의 송신 출력은 1.3W 급으로 설계하였고, 수신 G/T 규격을 만족하기 위해 TRM의 수신 잡음 지수를 5dB 이하가 되도록 설계하였다.

Characterization of mixing in an optimized designed T–T mixer with cylindrical elements

Abstract Passive micromixers are preferred over active mixers for many microfluidic applications due to their relative ease in integration into complex systems and operational flexibility. They also incur very low cost of manufacturing. However, the degree of mixing is comparatively low in passive mixers than active mixers due to the absence of disturbance in the flow by external forces and the inherent laminar nature of microchannel flows. Various designs of complex channel structures and three-dimensional geometries have been investigated in the past to obtain an efficient mixing in passive mixers. But the studies on mixing enhancement with simple planar geometries of passive mixers have been few and limited. The present work aims to investigate the possibility of mixing enhancement by employing simple planar type designs, such as T-mixer and T–T mixer with cylindrical elements placed in the mixing channel. The mixing performance has been evaluated in the Reynolds number range of 6 to 700. Numerical results have shown that T–T mixer with cylindrical elements performed significantly well and obtained very good mixing quality over basic T-mixer for the entire range of Reynolds number (6 to 700). The device has also shown better mixing as compared to basic T–T mixer and T-mixer with cylindrical elements. A larger pair of vortices formed in the stagnation area due to the presence of a cylindrical element in the junction. Cylindrical elements downstream caused significant enhancement in mixing due to splitting and recombining action. The size of the cylindrical element in the T–T mixer has been optimized to obtain better mixing performance of the device. Remarkable improvement in mixing quality by T–T mixer with cylindrical elements has been obtained at the expense of small rise in pressure drop as compared to other passive designs considered in this study. Therefore, the current design of T–T mixer with cylindrical elements can act as an effective and simple passive mixing device for various micromixing applications.

A Lumped-Charge Approach Based Physical SPICE-Model for High Power Soft-Punch Through IGBT

This paper presents a new lumped-charge approach-based physical model for high power soft-punchthrough (SPT) insulated gate bipolar transistor (IGBT). The IGBT physical models should consider the fabrication technologies used to optimize the device behavior for specific applications. The proposed model focuses on the chip structure designed by ABB for high power IGBT and can apply to other IGBTs with homogeneous structures. Based on the SPT+ concept combined with an enhanced planar cell design for the optimization of lower power losses, different particular mathematical approaches are used to describe their functions in the proposed model. The temperature dependence of the model is also included because the chip temperature of IGBT in practical applications is higher than the room temperature and changed with service conditions. The physics-based IGBT model has been implemented in PSpice and validated with experiments, which considers both the block voltage nonpunchthrough condition and punchthrough condition during turn-OFF transient. The simulation results show a good agreement with the experiment results.