Electromagnetically Aware Design of Capacitive Touch Sensor Panel Electrodes for Antenna Integration

Abstract

Modern electronic devices increasingly rely on efficient antenna integration strategies for supporting high-speed wireless connectivity. Especially for bezel-less displays, these antennas are generally placed underneath the touch sensor panel (TSP) where they interact strongly with the sensing electrodes. To overcome this problem, we engineer the shapes of these electrodes to facilitate the transmission of electromagnetic waves having frequency identical to the operating frequency of the integrated antenna. We thereby propose a new design methodology for TSP electrodes and demonstrate its advantages with respect to antenna integration. As an example, we present the design of a TSP that has a pass-band at 2.51GHz and 5.66GHz for TE polarization and 3.01GHz for TM polarization. We integrate a printed dipole antenna with the proposed as well as a standard TSP geometry, placing it right underneath rather than beside the panel. Comparing the radiation patterns at 2.5GHz, we show that the pattern is significantly different than its free-space one, when a standard TSP geometry is used. Yet, the proposed one leads to a pattern that is almost identical (improved by 3.93dB as compared to standard TSP) to that in free-space.