Circular Polarized Microstrip Antenna Design for Ambient IoT Communication and Sensing

Ambient Internet of things (AIoT) with low power consumption and low cost characteristics have been widely discussed and studied. Different from traditional coverage-limited RFID, AIoT applied in cellular network can further improve coverage by improving sensitivity, which can be used for wireless communication and sensing systems. AIoT device’s antenna as key radio frequency (RF) module needs to be carefully designed for receiver sensitivity. However, how to consider AIoT device’s antenna design is still an open issue. In this paper, a compact broadband circular polarized (CP) antenna is proposed for AIoT device, which is fed by a microstrip feedline positioned to the bottom of the patch. The proposed antenna is fabricated with a small patch area of 4.08×3.15×0.508 mm3. Results show that the impedance bandwidth for |S<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</inf>|<-10dB of proposed antenna is expanded to 27.56% (25.73 to 33.94GHz), axial ratio (AR) bandwidth for AR <3dB is enhanced to 14.74% (26.15 to 30.31GHz), and the peak gain is from 2.70 to 4.52 dBic within the AR band. The proposed antenna is suitable for AIoT communication and sensing in B5G and 6G systems.