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Analysis of Sustainable Materials for Radiative Cooling Potential of Building Surfaces
摘要： The main goal of this paper is to explore the radiative cooling and solar heating potential of several materials for the built environment, based on their spectrally-selective properties. A material for solar heating, should have high spectral emissivity/absorptivity in the solar radiation band (within the wavelength range of 0.2–2 μm), and low emissivity/absorptivity at longer wavelengths. Radiative cooling applications require high spectral emissivity/absorptivity, within the atmospheric window band (8–13 μm), and a low emissivity/absorptivity in other bands. UV-Vis spectrophotometer and FTIR spectroscopy, are used to measure, the spectral absorption/emission spectra of six different types of materials. To evaluate the radiative cooling potential of the samples, the power of cooling is calculated. Heat transfer through most materials is not just a surface phenomenon, but it also needs a volumetric analysis. Therefore, a coupled radiation and conduction heat transfer analysis is used. Results are discussed for the selection of the best materials, for different applications on building surfaces.
关键词： sustainable materials,coupled radiation-conduction heat transfer,built environment,spectrally-selective surfaces,radiative cooling,roofs
更新于2025-09-23 15:22:29
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A novel miniaturized frequency selective surface
摘要： A novel single layer miniaturized frequency selective surface made of circular unit cell elements is presented in this article. The frequency selective surface (FSS) unit cell measures 0.055λ0 × 0.055λ0, where λ0 corresponds to its free space wavelength. The proposed FSS offers band stop characteristics with bandwidth of 137.5 MHz centered at 1.39 GHz. The symmetrical structure of the unit cell elements provides polarization independency. The miniaturized unit cell elements help achieving angular independency for both TE and TM mode of polarization. The miniaturized design provides excellent angular independency with negligible frequency shift for varying incident angles. A prototype of the FSS is fabricated and its simulation results are validated using measurements.
关键词： polarization,frequency selective surfaces (FSS),miniaturization
更新于2025-09-19 17:15:36
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[IEEE 2019 IEEE 69th Electronic Components and Technology Conference (ECTC) - Las Vegas, NV, USA (2019.5.28-2019.5.31)] 2019 IEEE 69th Electronic Components and Technology Conference (ECTC) - Fully Additively Manufactured Tunable Active Frequency Selective Surfaces with Integrated On-package Solar Cells for Smart Packaging Applications
摘要： A ?rst-of-its-kind fully inkjet-printed electronically tunable active ?exible frequency selective surface (FSS) using varactors with integrated on-package solar cells is presented in this paper. Each varactor is biased by a dedicated on-package inkjet-printed solar cell using a low-temperature fabrication process. The solar cell changes its output voltage with variation in light intensities that eventually leads to a change in capacitance of the varactor and overall frequency response of the FSS. The proposed design eliminates the use of labor intensive biasing network, bulky power supply and micro-controllers to tune the FSS frequency response. These structures presents an autonomous, ultra low cost on-package RF shielding mechanism for next-generation of system-on-chip packaging applications that can be tuned on-demand at different frequency bands by simple variation of incident light intensities. Thus making them useful for a wide range of terrestrial, outer-space and EMI shielding applications.
关键词： Additive manufacturing,tunable FSS,solar cells,Frequency selective surfaces,varactors,tunable RF structures,inkjet printing
更新于2025-09-16 10:30:52
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Compact three-dimensional bandpass FSS with high selectivity based on split square coaxial waveguide
摘要： In this Letter, a compact three-dimensional (3D) frequency selective surface (FSS), exhibiting a bandpass filtering response with high selectivity, is proposed based on the split square coaxial waveguide (SSCW). The unit cell of the presented 3D FSS consists of one parallel-plate waveguide propagation path and one SSCW propagation path. In the SSCW path, two identical short SCWs are produced by employing a centred annular slot. Each short SCW intrinsically provides a square slot resonance. Owing to the electromagnetic coupling between these two square slot resonances, original single square slot resonant mode will split into even-/odd-resonant modes, resulting in a flat passband with two transmission poles. Moreover, two transmission zeros located at both sides of the passband are introduced for high selectivity, because the electromagnetic waves passing through these two different paths are combined out of phase. By investigating the electric-field distributions at the frequencies of the transmission zeros/poles, the operating principle of the proposed 3D FSS is described. A prototype of the proposed 3D FSS is fabricated and measured. The measured results show that the proposed design can achieve a stable response under the incident angles up to 60° for both TE and TM polarisations.
关键词： frequency selective surfaces,bandpass filtering,compact,split square coaxial waveguide,high selectivity
更新于2025-09-16 10:30:52
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Dual-Band Frequency Selective Surface on Aperture-Coupled Patch Resonators with Different Polarization Rotation
摘要： In this letter, a dual-band frequency selective surface (FSS) based on aperture-coupled patch resonators is proposed to achieve different angles of polarization rotation, that is, 90o and 0o. The dual-band response is achieved by periodically arranging two independent sub-elements consisting of back-to-back patch resonators with coupling apertures etched on the middle metallic layer. Herein, the first passband is realized by the crossed patch resonators with a pair of rectangular apertures etched beneath the edges of the crossed patches. It can produce 180o phase difference between the two orthogonal components of a linearly polarized (LP) incident wave oriented to the diagonal of the FSS elements, thus rotating the incident polarization to its orthogonal one in this first passband. The second passband is caused by the square patch resonators with crossed apertures etched beneath the center of the square patches, thereby maintaining the incident polarization unchanged in this second passband. The operation principle is then extensively analyzed and discussed. To validate the design concept, the proposed FSS is designed, fabricated, and measured. Good agreement between the measured and simulated results is achieved to reveal the attractive dual-band and dual-polarization features of the proposed FSS.
关键词： Dual-band,aperture-coupled patch resonators,polarization rotation,frequency selective surfaces
更新于2025-09-16 10:30:52
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Solar Engineering of Thermal Processes, Photovoltaics and Wind || Radiation Characteristics of Opaque Materials
摘要： This chapter begins with a detailed discussion of radiation characteristics of surfaces. For many solar energy calculations only two quantities are required, the solar absorptance and the long-wave or infrared emittance, usually referred to as just absorptance and emittance. Although values of these two quantities are often quoted, other radiation properties may be the only available information on a particular material. Since relationships exist between the various characteristics, it may be possible to calculate a desired quantity from available data. Consequently, it is necessary to understand exactly what is meant by the radiation terms found in the literature, to be familiar with the type of information available, and to know how to manipulate these data to get the desired information. The most common type of data manipulation is illustrated in the examples, and readers may wish to go directly to Section 4.5.
关键词： selective surfaces,solar energy,infrared emittance,solar absorptance,radiation characteristics
更新于2025-09-16 10:30:52
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[IEEE 2018 12th International Congress on Artificial Materials for Novel Wave Phenomena (Metamaterials) - Espoo, Finland (2018.8.27-2018.9.1)] 2018 12th International Congress on Artificial Materials for Novel Wave Phenomena (Metamaterials) - Self-complementary tessellations as universal design approach for LP-to-CP transforming frequency selective surfaces
摘要： Recently self-complementary frequency-selective surfaces (FSSs) have been shown capable of linear-to-circular polarization transformation. In this work we numerically and experimentally prove generality of this approach showing that similar self-complementary tessellations can be used as FSS patterns in both the microwave and the sub-millimeter wave ranges. Moreover, we simulated two Escher’s tessellations as patterns of microwave FSSs to further demonstrate the polarization transform function of arbitrary self-complementary FSSs.
关键词： linear-to-circular polarization transformation,self-complementary tessellations,microwave,sub-millimeter wave,frequency-selective surfaces
更新于2025-09-10 09:29:36
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Ultra-Miniaturized Low-Profile Angularly-Stable Frequency Selective Surface Design
摘要： In this study, an ultra-miniaturized low-profile angularly-stable frequency selective surface (FSS) based on 2.5-dimension convoluted interwoven element is designed. The dimension of FSS element is 0.014λ0 × 0.014λ0, where the λ0 represents the free-space wavelength of resonance frequency. The thickness is only 0.0015λ0. When the FSS is illuminated by electromagnetic wave, the frequency selective properties perform stable under different incident angles up to 85° for both TE and TM polarization. For better understanding, the operation mechanism, the design procedure, distribution of surface current, and equivalent circuit are presented. A prototype of proposed FSS is fabricated, the measurement results prove the validity of simulated ones. To further improve the performance, using the same design procedure, the size and thickness of designed FSS have been reduced to 0.0053λ0 × 0.0053λ0 and 0.00061λ0, respectively. Since the resonance frequency of proposed FSS is adjustable at any desired frequency, an ultra-miniaturized low-profile angularly-stable FSS for GSM 900 band has been designed. The designed FSS can be applied in GSM shielding effectively.
关键词： frequency selective surfaces (FSSs),spatial filters,Convoluted element,2.5-D structure,miniaturization
更新于2025-09-10 09:29:36
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A Novel Faraday-Cage Inspired FSS Shield for Stable Resonance Performance Characteristics
摘要： In this latter, a novel Faraday cage inspired frequency selective surface (FSS) array is illustrated to patch-type periodic element. A metallic via has been used to stow the two patch conducting arrays printed on either side of the substrate. The intended application of the proposed electromagnetic (EM) structure is at microwave frequencies for improved bandwidth characteristics and stable resonance response. The structure shows a very stable resonance performance up to 60o oblique incident angle and 11.52% improvement in its fractional bandwidth. In addition, the simulation results of proposed design prove the validity of proposed structure for high microwave powers. Finally, the fabricated prototype along with experimental results of the Faraday cage array show the efficacy of proposed structural design.
关键词： Faraday cage,High power handling,Electromagnetic (EM) performance,Frequency Selective Surfaces (FSS),Substrate Integrated Waveguide (SIW)
更新于2025-09-10 09:29:36
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Assessing Transparency Control of Southern European Building Wall Structures Using Frequency-Selective Surfaces [Wireless Corner]
摘要： The concept of controlling the radio-frequency (RF) transparency of building wall structures is analyzed in this article with a focus on southern European architecture, where it is demonstrated that some materials have a significant impact on wireless propagation. As such, the integration of frequency-selective surfaces (FSSs) in some building structure arrangements might have few overall benefits. This work provides an analysis of the different elements required to modify the electromagnetic (EM) transparency of building wall layers: 1) different methods to control the frequency selectivity are identified with a special focus given to FSS, 2) some proposals on the integration of the FSS on current and new building structures are provided, 3) measurement results are presented regarding the penetration losses of multilayered wall samples, with and without the presence of FSS layers, and 4) a multilayer EM simulation tool developed in MATLAB is introduced and validated against measurement results, allowing the simulation and analysis of additional scenarios. Results are provided for a frequency range of 800 MHz up to 10 GHz.
关键词： penetration loss,building materials,electromagnetic transparency,Frequency-selective surfaces,wireless propagation
更新于2025-09-09 09:28:46