Area Optimized Rectangular Spiral Antenna for Bluetooth Communication

In this paper, a simulated design of a rectangular spiral antenna is proposed. The antenna is tuned for communication in the ISM band at 2.4GHz. The frequency of choice enables the proposed antenna to be used in a number of IoT based devices using popular wireless networks like Bluetooth and WiFi. The design has been built with FR4 material as the substrate with conductive copper lines, which can be easily fabricated on a PCB. When the coil is used to communicate at 2.374 GHz, the reflection coefficient is -3 0.5 dB, with a bandwidth of 150.7 MHz for parallel to S11 parallel to <= -10 dB, i.e., a fractional bandwidth of 6.53%. The VSWR is obtained to be 1.05 at 2.374 GHz. The radiation efficiency at 2.4 GHz is obtained as 38.3%. A thorough comparative study with a traditional coil and the effects of separating the outermost coil on bandwidth, radiation efficiency, parallel to S11 parallel to and VSWR has also been studied. Overall, we see a 70.3% reduction in area when compared with existing works. Our paper also lays out the methodology to tune rectangular spiral antennas to certain frequencies. This research is a 1 of 3 work, with the scope to go towards multi functional coil design capable of Bluetooth Communication, Capacitive touch and Wireless Charging.