A case study of 4 GHz proximity detector for smart crosswalks

A 4 GHz line-of-sight propagation scenario is tested experimentally to assess the implementation of a proximity detector for smart city applications, smart crosswalk in particular. Preliminary results indicate that 4 GHz frequency could be used to monitor the presence of people, the received power decreasing sufficiently enough to make a trustful decision that could trigger the traffic lights. Microstrip antenna arrays are used to increase the radiative efficiency and a maximum distance of 2 meters is chosen for experiments, corresponding to the width of many crosswalks existent around Romanian high schools.