Optically Transparent Microstrip Patch-Based Antenna with 3D Pattern Diversity

Energy-starved devices can rely on solar panels to power themselves, collect sensor data, and send it wirelessly to a fixed base station. Thus, vertically integrated microstrip patch antennas with optical transparency are very promising. A known method to achieve high transparency and efficiency is the meshed conductor approach. Nevertheless, the impedance bandwidth of regular meshed antennas does not cover the whole 2.4 GHz band used by typical protocols like BLE. On the other hand, optimization of how the collected energy is spent becomes extremely relevant. Antenna designs with spatial pattern diversity can be implemented to automatically adapt and focus the radiation only in the direction of communication towards the base station avoiding power wastage. In this paper, a dodecahedron hollow acrylic structure is used as antenna substrate for twelve microstrip patch antennas that can be activated independently by using radiofrequency switches. Moreover, the bandwidth of the radiators is enhanced by implementing E-shape microstrip patches. The final design has 96% transparency, impedance bandwidth of 6.98 %, and a gain of 6.1 dBi at 2.45 GHz.