A unidirectional wideband WiFi/NB-IoT on-glass antenna with AMC reflector for smart building applications

Abstract This paper presents a low-profile on-glass antenna solution for smart building applications that supports both WiFi and Narrowband Internet of Things (NB-IoT) connectivity and can be integrated with glass doors and windows. As a preliminary step, five architectural glass types were characterized in terms of dielectric properties, leading to the selection of 3 mm clear glass as the optimal antenna substrate. The initial antenna, a rectangular monopole with asymmetric coplanar ground, demonstrated wideband operation from 1.53 to 2.63 GHz, covering the 2.1 GHz NB-IoT and 2.4 GHz WiFi bands, 1.72–3.9 dBi gain, high radiation efficiency, and a bidirectional radiation pattern suitable for coverage on both sides of the glass. To enable applications requiring directional coverage and higher gain, the antenna was combined with a dual-band artificial magnetic conductor (AMC) surface, implemented on a separate 3 mm clear glass substrate. This integration enhanced the forward gain to 7.7–8.4 dBi while suppressing backward radiation, with simulation and measurement results showing good agreement. The proposed AMC-integrated on-glass antenna therefore combines wide bandwidth, high efficiency, and flexible bidirectional or unidirectional operation, making it a strong candidate for next-generation IoT-enabled architectural elements in smart buildings.