A compact, robust, chipless radio frequency identification (RFID) tag is proposed. Resonant elements patterned in a concentric fashion encode data in the spectral domain employing frequency shift encoding. The proposed tag encodes 28.25 data bits over a miniscule physical footprint of 25 × 25 mm2. The formulated scheme is demonstrated to be viable for encoding of temporal variables. The electromagnetic performance of the presented design is investigated for different laminates: Rogers RT/duroid® 5880 and Taconic TLX‐0. Multiple tag prototypes employing a variety of substrates are realized and evaluated for in‐laboratory performance. The proposed design is compared with existing work reported in literature. Code density of 4.52 bits/cm2 has been successfully achieved. The tag design operates from 3.07 to 10.6 GHz and is readily realizable on flexible laminates. Smart retail, intelligent packaging, adaptive ticketing, and similar time‐related applications can be materialized using the proposed tag.

Smart cities are improving the urban quality of life. The cities are providing more and more facilities to enhance the living standards of city residents. Implementation of smart cities has improved the services provided by various urban systems. Out of the various challenges being faced by smart cities, most important are the privacy / security of its residents and sanctity of data systems. Traditional cyber security protection policies cannot be applied directly to smart city applications. Furthermore, it is important to identify these cyber threats so as to design and implement effective countermeasures. In this paper we will focus on current measures being taken to counter privacy and security threats to smart cities, identify limitations of these measures and also present future trends in this field. This research allows users of the domain to select an appropriate technology for relevant security threat and to design smart cities application according to their needs.