Large and Optically Transparent Multilayer for Broadband H-Shaped Slot Antenna

This letter presents a feasibility study of a large optically transparent broadband antenna for urban radio cellular networks. The proposed H-shaped slot antenna, which is well suited for antenna arrays, is made of three transparent and conductive layers printed on three glass substrates separated by two air gaps. The size of the antenna is close to 300×300×20 mm³. The transparent and conductive coatings used to fabricate the antenna are made of a silver grid layer (AgGL) deposited on one side of each 1.1-mm-thick 1737 Corning glass substrate. The theoretical optical transparency of the multilayer antenna ranges between 51.6% and 70.7% over the whole visible light spectrum. The measured electromagnetic performance of the transparent H-shaped slot antenna has been compared to that of a nontransparent (but geometrically identical) simulated antenna. The results show a similar behavior and performance in terms of bandwidth, radiation pattern, and gain. This confirms the restriction of the ohmic loss and skin depth loss from the AgGL material. These also provide the ability to implement large transparent antennas with performance identical to that of nontransparent ones, and most importantly with the advantage of a soft visual impact on urban environment.