Structured transparent low emissivity coatings with high microwave transmission

Abstract

In order to reduce the energy consumption of buildings, modern windows include metal-containing coatings. These coatings strongly attenuate the microwaves used for mobile communications. Here, we present a novel approach to improve radio signal transmission by structuring a low emissivity coating. Laser ablation is used to scribe a line pattern on the coating. The microwave attenuation of the initial coating ranges between-25 and-30 dB between 850 MHz and 3 GHz. The optimized patterning reduces it down to-1.2 ± 0.6 dB. The fraction of the ablated area is relatively low. Our experimental results show that it is possible to reach a level of attenuation close to that of a glass substrate by removing less than 4% of the coating area. The ablated lines are thin enough to not be noticed in most common lighting situations. Therefore, we achieve a dual spectral selectivity: the coated glass is transparent in the visible range, reflective in the infrared and nearly as transparent as its glass substrate to microwaves. Additionally, numerical simulations were performed and show that the attenuation at grazing incidences is dominated by the behaviour of the glass substrate. To the best of our knowledge, it is the first time that experimental evidence for the combination of such properties is reported and that detailed experimental data are compared to numerical simulations. We anticipate that our findings will be of major importance for the building and transportation sectors.

Performance Assessment of a nZEB Carbon Neutral Living/Office Space and Its Integration into a District Energy-Hub

“…An intensive use of daylight and passive solar gains is achieved within the unit, besides reaching a positive energy balance over the whole year through 'on-site' generation of solar power and heat. The SolAce unit comprises multifunctional facades involving several novel technologies developed by the research group of Nanotechnology for Solar Energy Conversion at EPFL Solar Energy and Building Physics Laboratory: this includes nanotechnology-based glazing for solar photovoltaic modules [13] and solar thermal collectors [14], innovative micro-structured glazing providing seasonal dynamic management of daylight and solar gains [15,16], and insulating triple glazing with laser-engraved special low emissivity (low-e) coatings for enhanced telecommunication signal transmission [17,18] (Figure 2d). Advanced building sensing and control technologies interact with façade elements and the indoor environment: fostering human-building interaction (HBI), they provide a user-centric approach favoring users' visual and thermal comfort.…”

Combinational Approach of Energy Management for Sustainable Food and Crop Storage Facilities: A Research Concept

“…The low-E coatings are typically structured as dielectric/metal/dielectric (DMD) multilayer thin films deposited by various methods, promotes the strong and very wide-band reflection of thermal infrared wavelengths. Recently energy harvesting PV glass windows (contain thin-film coating) capable of on-site energy generation simultaneous with the functionality of tailoring the incident sunlight spectrum required for different crops that improve production yields, can be useful for the design and building of innovative and cost-effective greenhouses for horticultural industries [29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44].…”

Radiofrequency transmission through rectangular apertures in perimetrally uncoated low emissivity windows

“…This feature is obtained by the deposition of nanometric layers of different materials, some of them metals, over the glass substrate. Depending on the placement of these coatings, advanced glasses can attenuate infrared light in a hot climate (solar control glass) or prevent thermal losses in cold weather (low emissivity glass) [1,2]. Metallic coatings, however, also result in an important attenuation (30-40 dB) of the electromagnetic waves in the mobile communication frequency range [3,4].…”