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Simulation of the resonance frequencies due to glass cavities (without coating) where the air gap is varied. Specific frequencies at 14.86 and 29.81 GHz show excellent transmission for every air gap distance
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A simulation model and an experimental characterization of energy saving glazing transparent to mobile communication frequency up to 40 GHz is presented. A previous study showed that laser structured energy efficient windows with a frequency selective surface greatly reduces the microwave attenuation for frequencies below 5 GHz, while preserving th...
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... Though many advances have been achieved in designing high transmission structures, there still exist some limitations to overcome: 1) for transverse-magnetic (TM) polarization, there exists a trapped mode with an abrupt drop in the transmission curve; 2) there is a frequency shift when the incident angle becomes large; 3) the previous AR layers have usually adopted multilayered structures, which are rather complicated with high costs; and 4) it is worth mentioning that bandpass frequency-selective surface (FSS) has been employed to enhance the RF transmission of the energy-saving glass [32], [33], [34], [35], [36], [37], [38], [39], [40], but the thick configuration, low RF transmittance, and sensitivity to incident angle still hinder their applications in practice. ...
High transmission of electromagnetic (EM) waves is closely related to the reliability and stability of the indoor-to-outdoor wireless communication system. Due to the serious EM attenuation of the normal glasses under large incident angles, transparent film coatings that can be attached to the glasses have attracted extensive attention to maintain high EM transmissions in a wide angle range. In this paper, a wideband and wide-angle single-layered transparent metasurface is proposed to enhance the EM transmissions through the glasses. Detailed mechanisms, analytical models and elaborate numerical results are presented. As a proof-of-concept, a prototype of the metasurface based on Ag metal mesh is fabricated and tested. The measured results are in good agreement with the numerical simulations and calculations, thus validating the excellent EM performance. It is expected that the proposed single-layered metasurface with high transmittance in both microwave and light bands can find potential applications in the 5G and 6G communication scenarios.
... Another analytical approach is the equivalent-circuit modelling technique [117]. A few researchers [31,33,118] have utilized this method to design and study the response of FSS patterns with selected signal frequencies. For instance, Bouvard et al. [31] used this approach to estimate the signal transmission through a square FSS pattern on a low-e window. ...
... . C f ss (1) For the case of the FSS square pattern, the capacitance C f ss at a normal incidence is calculated as follows [31]: [118]. Reprinted with permission from Ref. [32], Copyright © 2017 Elsevier B.V. All rights reserved. ...
... Reprinted with permission from Ref. [32], Copyright © 2017 Elsevier B.V. All rights reserved. Reprinted with permission from Ref. [118], Copyright © 2020, Springer-Verlag GmbH Germany, part of Springer Nature. ...
The commercial building and residential sectors are responsible for 27% of the global electricity consumption, with cooling and heating loads being the dominant contributors. Much of the thermal energy inside of buildings is wasted by means of transmission through conventional windows. Low emissivity (low-e) windows have been incorporated as an effective method to minimize energy utilisation because of their ability to reflect external heat radiation, thus reducing cooling loads. Such windows have been widely used in the architectural and automotive sectors to block both ultraviolet (UV) and infrared (IR) radiation from the Sun. The windows consist of multi-layer thin coatings (metallic and dielectric layers), which are highly transparent in the visible but reflective to IR radiation (heat). However, the metallic layers attenuate telecommunication signals used for modern-day telecommunications such as radio frequency (RF) and microwave (μW) signals. As there is an ever-increasing demand for a reliable interior to exterior mobile communication coverage, these windows need to be transparent for reliable wireless communication. A class of engineered materials is a promising solution to improve signal transmission through low-e windows; by applying a frequency selective surface (FSS) pattern onto the window. FSS can be realised by producing a periodic of repetitive shapes incorporated onto the window surface to filter selective electromagnetic waves. This review highlights the FSS patterning technique applied onto low-e windows to allow for low attenuation transmission of telecommunication signals.
... The overall frequency response of the structure is determined by the element type and shape, substrate characteristics, number of layers and inter-element spacing. Due to the high demand of wideband pass FSS, many structures have been reported recently [5][6][7][8][9]. In the past few years, a number of 2-D, 2.5-D, and 3-D topologies have been proposed to enhance the operational BW of the bandpass FSS. ...
In this paper, a novel loop-based multiband bandpass frequency selective surface (FSS) structure has been presented. The presented unit cell has been designed using the two square loops and two octagon loops for achieving the multiband characteristics, which are extensively utilized in a wide range of applications. The sporadic arrangement of these four loops is the key factor in passing the Wi-Max (2.5-2.7 GHz, 3.4-3.6 GHz) and WLAN (center frequency 5.5 GHz) frequency bands. The miniaturized structure gives a wide bandwidth at all three bands and provides stable resonance for a wider angle of incidence due to the orientation of loops. The size of the unit cell is 0.15 k 9 0.15 k, where k is the wavelength of the first resonant frequency. A 16 9 16 array of the proposed unit cell is fabricated over a FR4 substrate, and its simulated and measured results are presented, which are in good agreement. The advantage of the proposed FSS structure is its miniaturized configuration showing wider angular stability and polarization-independent characteristics.
With the growing global energy demand and environmental issues, energy saving technologies are becoming increasingly important in the building sector. Conventional windows lack energy saving and thermal insulation capabilities, while Low emissivity glass (Low‐e glass) attenuates mobile communication signals while reflecting infrared. Therefore, this paper aims to design a type of windows for the “Sub 6GHz” frequency band of 5G. These windows combine the inherent transparency of traditional glass windows with the energy saving properties of Low‐e glass, while also ensuring optimal communication performance within the 5G (Sub 6G) band. The metasurface glass is fabricated and subjected to simulation‐guided experiments to evaluate their reliability and practicality. The metasurface glass is rigorously assessed in terms of microwave transmission performance, infrared low emissivity performance, and energy saving and thermal insulation capabilities.
Low emissivity (low-e) windows are widely used in the architectural sector to block the infrared (IR) radiation from the Sun. The windows contain a multilayer nanoscale coating of metallic and dielectric layers. The metallic layer, which is responsible for the IR reflection, also attenuates the radio and microwave frequencies used for modern-day technologies such as Fifth Generation (5G) communications. As there is an ever-increasing demand for a reliable interior-to-exterior signal coverage, low-e windows should be transparent to such signals. A class of surface modification - Frequency Selective Surface (FSS) is the technique of choice to be applied on the thin metallic coating to transmit the wireless signal.
In this work, a thin silver (Ag) film – 10 nm thick was deposited by electron beam evaporation on polycarbonate substrates as an example low-e coating. Despite excellent IR blocking (64 %) and visible light transmittance (60 %), it also presented a high attenuation of 20 dB at 5G signal bands (72 – 82 GHz). FSS patterns of various geometries and sizes were applied via laser ablation and evaluated to provide the lowest attenuation. We demonstrated that the application of the hexagonal pattern provided largest improvement reducing the 5G attenuation value from 20 dB to 1 dB, without compromising the visible transmittance and having only a minor effect on IR reflection.
In this paper, a novel loop based multiband bandpass frequency selective surface (FSS) structure
has been presented. The presented unit cell has been designed using the two square loops and two octagon loops
for achieving the multiband characteristics which are extensively utilized in wide range of applications. The
sporadic arrangement of these four loops is the key factor to pass the Wi-Max (2.5–2.7 GHz, 3.4–3.6 GHz) and
WLAN (center frequency 5.5 GHz) frequency bands. The miniaturized structure gives a wide bandwidth at all
the three bands and provides stable resonance for a wider angle of incidence, due to the orientation of loops. The
size of unit cell is 0.15 k 9 0.15 k where k is the wavelength of first resonant frequency. A 16 9 16 array of the
proposed unit cell is fabricated over a FR4 substrate and its simulated and measured results are presented which
are in good agreement. The advantage of the proposed FSS structure is its miniaturized configuration showing
wider angular stability and polarization independent characteristics.
With the purpose of reducing the heating energy in buildings, it is common practice to install energy-efficient windows to increase the thermal insulation of a façade. These insulating glass units (IGIJ) include a thin silver coating acting as an infrared mirror which reduces the thermal losses that occur through radiation, but at the same time reflects the microwaves for mobile communication. To address this drawback, a specific laser treatment is performed on the silver coating which strongly improves the transmission of microwaves through the window. In this study, the attenuation of microwaves signal was analyzed inside the SolAce unit in the "NEST" research building at the Swiss Federal Laboratories for Materials Science and Technology (EMPA) in Dübendorf. Two configurations (with and without laser-treated glazing) were carried out by interchanging two hinged windows. The results showed a significant improvement in signal strength in the configuration with laser-treated IGUs. A transmission loss contour plot of the SolAce unit showed a highly directional propagation of the wave which suggests that more than two windows should be treated to achieve better mobile communication in the entire unit. The novel patterned coating is thus especially valuable in the building sector to increase the microwave signal for mobile communication. To the best of our knowledge, this is the first implementation and testing of laser-treated coating for energy-efficient glazing in the building sector.
This paper presents transmission enhancement methods for low emissivity (low-E) windows at millimeter wavelength (mmWave) frequencies. These methods are required for installation of effective indoor customer premises equipment for mmWave fixed wireless access (FWA) services. Low-pass filtering frequency selective surfaces are patterned with low-E coatings by laser and the effects are verified theoretically and experimentally. Anti-reflection (AR) dielectrics are additionally utilized and found to reduce transmission loss in various types of window regardless of frequency and incident angle. The results of the current study achieve lower losses for various types of window and incident angles. A transmission loss improvement is also achieved in a real FWA scenario, which can be applied for the coverage extension of FWA services.
