Frequency selective surface-based sensing: Theory and applications. Mahboobeh Mahmoodi. FSSs have been utilized for different applications such as spatial filters, reflectors, lenses, radomes, and more recently, as sensors. FSS-based sensors have shown potential for numerous applications in structural health monitoring such as crack detection, concurrent strain and temperature sensing, normal and shear strain sensing, inspection of layered structures, etc.
As FSS-based sensing is largely undeveloped, there are many critical aspects that must be fully understood before this sensing approach can be fully utilized.Pistola de calor stanley
Therefore, the goal of this research is to advance the science behind FSS-based sensing in order to create a platform of knowledge upon which future engineers may utilize when designing FSS-based sensors. To this end, the theoretical assuming infinite dimensions and a uniform excitation FSS response is modeled using a cavity-based coupled-mode theory and subsequent quality factor analysis for patch and loop unit cells in order to study the effect of unit cell dimension, element geometry and substrate properties on the FSS frequency response.
In addition, the differences between theoretical and practical FSSs are studied in order to obtain design rules and metrics to achieve a reliable localized sensing measurement by an FSS sensor, thereby improving the sensing resolution from the dimensions of the sensor to smaller 'cells' within the sensor.
Then, to achieve the maximum resolution of the FSS sensor, an approach is presented to determine the optimal sensor cell size.
Additionally, a method using synthetic beamforming is presented to obtain an adaptive resolution for FSS sensing"--Abstract, page iv. Patch- and loop-based frequency selective surface based on quality factor approach Patch- and loop-based frequency selective surface model based on the quality factor approach Performance metrics for frequency selective surface-based sensors An aperture efficiency approach for optimization of FSS-based sensor resolution Adaptive resolution for localized FSS-based sensing by synthetic beamforming.
Mahmoodi, Mahboobeh, "Frequency selective surface-based sensing: Theory and applications" Doctoral Dissertations. Electrical and Computer Engineering Commons. Advanced Search. Privacy Copyright.
Energy and Communication Efficient FSS for Equivalent Model of Hard-Coated Energy Saving Glass
Title Frequency selective surface-based sensing: Theory and applications. Author Mahboobeh Mahmoodi. Department s Electrical and Computer Engineering.Kmspico activator for windows server 2008 r2
Publisher Missouri University of Science and Technology. Note about bibliography Includes bibliographic references. Recommended Citation Mahmoodi, Mahboobeh, "Frequency selective surface-based sensing: Theory and applications" Included in Electrical and Computer Engineering Commons.
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FSSs have been used for filtering electromagnetic waves for many years. Conventional FSSs use metal patch pattern as periodic element. This paper takes the plasma tube as a substitution for metal patch. The 3-D finite-difference time-domain method with periodic boundary condition is utilized to simulate the interaction of incident wave and plasma FSS.
Numerical calculation results in that electron number density of plasma can dominate the resonance frequency obviously. The resonance frequency increases as the increasing of electron number density of plasma to the limit of that of perfectly electric conductor.
Thus, the FSS can be designed to be tunable by changing the ionized electron number density. Both of the noncollision and collisional plasma model are introduced to study the FSS characteristics. The numerical calculation results show that the collision frequency only influences the reflectivity while has no effect on the resonant frequency. The resonant frequency and transmitted power ratio can be tuned by assigning the plasma's electron number density and collision frequency.
Thus, plasma elements offer the possibility of improved shielding effect along with reconfigurability. Article :. Date of Publication: 08 February DOI: Need Help?Skip to Main Content. A not-for-profit organization, IEEE is the world's largest technical professional organization dedicated to advancing technology for the benefit of humanity.
Use of this web site signifies your agreement to the terms and conditions. The proposed FSS is made of convoluted square and circular loop elements, which are employed on the opposite surfaces of the RO substrate. The overall dimensions of the FSS are reduced to 0.
It has a bandwidth of 9 GHz to reduce the harmful effects on the human body due to EMI caused by radio transceivers. It can also be employed as a sub-reflector to enhance the gain and the bandwidth of the antennas.
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Actions Shares. No notes for slide. Sarkar 1,2,3,4 D. Evolution of FSS Cont. These scattered radiation add up which makes transmission of that signal. By controlling the scattered field, we can able to design required filter response. Simulation Setup Methods The methods used to setup the simulation are outlined. The arrays of metallic patches are aligned on top of a dielectric substrate.
The substrate is basically glass-PTFE. Its dielectric constant is 2. Periodicity is taken 24 mm along both X and Y direction for constructing array of patches. Observations Cont. Within this transformed patch, a circular shaped slot is cut.
Compactness has been achieved as the resonant frequency shifts towards left side, i. Also the value of percentage bandwidth obtained are Looks like you are currently in Russia but have requested a page in the United States site. Would you like to change to the United States site? Ben A.
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Frequency selective surface
Undetected location. NO YES. Frequency Selective Surfaces: Theory and Design. Selected type: Hardcover. Added to Your Shopping Cart. Print on Demand. View on Wiley Online Library. This is a dummy description. Ben has been the world-wide guru of this technology, providing support to applications of all types.
His genius lies in handling the extremely complex mathematics, while at the same time seeing the practical matters involved in applying the results. As this book clearly shows, Ben is able to relate to novices interested in using frequency selective surfaces and to explain technical details in an understandable way, liberally spiced with his special brand of humor Ben Munk has written a book that represents the epitome of practical understanding of Frequency Selective Surfaces.
He deserves all honors that might befall him for this achievement. Bahret was with the United States Air Force but is now retired. From the early 50s he sponsored numerous projects concerning Radar Cross Section of airborne platforms in particular antennas and absorbers. Under his leadership grew many of the concepts used extensively today, as for example the metallic radome. In fact, he is by many considered to be the father of stealth technology. It is woven with the physical insight that he has gained and further developed as his career has grown.Juventud adolescencia en ingles
Ben uses mathematics to whatever extent is needed, and only as needed. This material is written so that it should be useful to engineers with a background in electromagnetics. The physical insight that may be gained from this book will enhance their ability to treat additional array problems of their own. Professor Leon Peters, Jr. From the early sixties he worked on, among many other things, RCS problems involving antennas and absorbers.
However, it also gives the reader the tools to analyze multi-layered FSS's leading to specific designs of the very important Hybrid Radome, which is characterized by constant band width with angle of incidence and polarization. Further, it investigates in great detail bandstop filters with large as well as narrow bandwidth dichroic surfaces. It also discusses for the first time, lossy elements used in producing Circuit Analog absorbers.
Finally, the last chapter deals with power breakdown of FSS's when exposed to pulsed signals with high peak power. The approach followed by most other presentations simply consists of expanding the fields around the FSS, matching the boundary conditions and writing a computer program. While this enables the user to obtain calculated results, it gives very little physical insight and no help in how to design actual multi-layered FSS's.
In contrast, the approach used in this title analyzes all curves of desired shapes. In particular, it discusses in great detail how to produce radomes made of FSS's located in a stratified medium Hybrid Radomeswith constant band width for all angles of incidence and polarizations.
We've also updated our Privacy Notice. Click here to see what's new. We report the design, fabrication, and measurement of a broadband metamaterial absorber, which consists of lossy frequency selective surface FSS and a metallic ground plane separated by a dielectric layer. The compact single unit cell of the FSS contains crisscross and fractal square patch which couple with each other. In the end, the designed absorber was realized by experiment.
Microwave absorber is a kind of function material that can be used in stealth technology. The applications in areocraft such as battleplan and missile determine that the absorber must have broadband wave absorbing performance to reduce the probability of being explored. As a potential candidate of high performance wave absorber, the researches of the metamaterial absorber are mostly concentrating on the perfect and multi-bands absorption [ 1 — 5 ].
Usually the Jaumann screen and lossy frequency selective surface FSS could realize broadband radar absorber [ 6 — 9 ].Europe lockdown map december 2020
Because of the egregious thickness of the Jaumann screen [ 6 ], lossy FSS absorber, which is consist of resistive FSS and dielectric substrate, is the best choice of the broadband absorber [ 9 ]. The main means of study the FSS absorber are numeric method and equivalent circuit method [ 910 ], also some optimization method is necessary due to the parameters determining the wave absorbing performance [ 1112 ].
As to the single layer lossy FSS absorber, broadband wave absorbing performance can be realized through any FSS patterns [ 89 ]. But the optimal bandwidths of the familiar FSS absorbers have not been reported up to now.
On the other hand, unlike the numerous FSS patterns designed in the HIP high impedance surface field [ 13 — 16 ], the FSS patterns reported in the lossy FSS absorber by far are simple, such as square patch, crisscross, and ring, whose impedance are represented by series RLC circuit [ 9 ].
In this letter, based on the optimized results of the conventional absorber, we report a broadband lossy FSS absorber using crisscross and fractal square patch to form a compact single particle.
The reflectivity of the absorber exhibits three apexes in the frequency range of GHz. Moreover, owing to symmetry geometry, the absorber is independent on the polarization of an incident wave.
Take the square patches shape as an example; the three-dimensional sketch of the lossy FSS absorber is shown in Fig. The FSS pattern can be changed arbitrarily. Figure 1 b shows the circuit model of the absorber with simple FSS. In reference [ 9 ], the form of the two absorption nulls of the absorber was explained by circuital approach, and the wave absorption performance can be improved by adjusting the square resistance of the FSS.
The optimization is performed based on Finite-Difference Time-Domain method. Both the magnitude and bandwidth of the reflectivity are considered in the goal function.
The relative bandwidth unsatisfied the reflectivity threshold is nBWand the average linear reflectivity is R a which varies from 0 to 1. The weight coefficient of the bandwidth and the reflectivity in the goal function is and 1, respectively.
In the optimization process, the decrease of the nBW provides the main contribution to the minimum of the goalfunction. After optimizing the parameters of the absorber repeatedly, simulation results of reflection properties of the lossy FSS absorbers with different FSS pattern are obtained. The results are shown in Fig. As shown in Fig. The bandwidth with the reflectivity belowdB of the 3mm and 4mm thick simple FSS absorber are 7. Increase the number of the reflectivity apex, especially in the low frequency, could enhance the bandwidth possibly.Condiment meaning in hindi
The corresponding circuit model is shown in Fig. The crisscross and fractal square patch along the electric field direction can be modeled as series RLC circuit R fL 1and C 1 in Fig.A compact frequency selective surface FSS for 5G applications has been designed based on 2.
The proposed element consists of two main parts: the successive segments of the metal traces placed alternately on the two surfaces of the substrate and the vertical vias connecting traces. Furthermore, a general equivalent circuit model is established to provide direct physical insight into the operating principle of this FSS. A prototype of the proposed FSS has been fabricated and measured, and the results validate this design.
In recent years, frequency selective surfaces FSSs have drew extensive attentions because of their wide applications in the communication equipment [ 12 ]. FSSs are always designed to reflect, transmit, or absorb electromagnetic wave, and they are applied in the design of antenna radomes, reflector of low-profile antenna, electromagnetic absorbers, and so on [ 3 — 7 ].
The typical FSS structures consist of two-dimensional 2D periodically arranged resonate units [ 8 — 10 ]. In practical design, the number of FSS units is restricted to the requirement of size. For 5G communications, the antennas are very small and the radomes covering the antennas should be small as well [ 11 ].
However, when the infinite period of the FSS is truncated, it is bound to have a significant impact on the performance of the FSS. In order to maintain original performances and compromise this constraint, compact FSS elements are required. At present, several methods are proposed to realize the miniaturization of FSS. By adding some lumped reactive components to their design, the size of FSS element has been reduced because of the increasement of the inductance and capacitance of equivalent circuit [ 12 ].
In [ 13 ], the miniaturization of element is realized by reducing the thickness of dielectric substrate, so that the capacitance between various metallic layers has been increased.
Moreover, a loop-wire structure has been introduced in [ 14 ], which consists of a metallic patch and wire-grid on the opposite layer of substrate to enhance the inductance and capacitance.How to Simulate Frequency Selective Surface (FSS)
The FSS element consists of four symmetrical spiral patterns of metallic meander lines which has been designed to increase the length of resonant structures in a given periodicity [ 15 ].
In [ 16 ], the spiral slot element with a compact arrangement has been proposed, which effectively increases the corresponding equivalent inductance. And the corresponding equivalent capacitance can also be increased by adjusting the distance between every two slots. More recently, square loop with vertical vias is applied to design FSS element [ 17 ].
In this design, the capacitance is increased by the capacitive coupling of adjacent via wall, and the inductance is increased by using the knitted structure alternately across different layers of substrate.
For 5G mobile communications, further size reduction should be investigated. In this paper, novel miniaturized FSSs based on 2. The FSS element uses 41 vias to provide additional inductance and capacitance due to extensive path and via wall coupling between adjacent elements.
Moreover, this FSS provides good resonant stability for various polarizations and incident angles. The equivalent circuit model of the FSS has also been proposed for the analysis of its performance. Finally, to validate the results of proposed FSS, a prototype has been fabricated and measured. The proposed 2. The results show a good consistency between the full-wave simulations and measurements. The FSS element can be treated as a resonance circuit when it is illuminated by the incident waves.
The resonant frequency is determined by the formulawhere and represent equivalent inductance and capacitance of the element, respectively. Therefore, the method of miniaturization technique is to increase the value of inductance and capacitance. Based on this theory, the proposed structure of the 2. In Figure 1the metallic segments of the straight-line type FSS element are alternately placed on the top and bottom surface of the substrate and then connected through the metallic vias.
The length of the planar element is and the width of its conductor is.
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