A Compact Dual-Band Millimeter Wave Antenna for Smartwatch and IoT Applications with Link Budget Estimation

Parveez Shariff Bhadrvathi Ghouse; Pallavi R Mane; Sangeetha Thankappan Sumangala; Vasanth Kumar Puttur; Sameena Pathan; Vikash Kumar Jhunjhunwala; Tanweer Ali

doi:10.3390/s24010103

A Compact Dual-Band Millimeter Wave Antenna for Smartwatch and IoT Applications with Link Budget Estimation

Sensors (Basel). 2023 Dec 24;24(1):103. doi: 10.3390/s24010103.

Authors

Parveez Shariff Bhadrvathi Ghouse¹, Pallavi R Mane¹, Sangeetha Thankappan Sumangala², Vasanth Kumar Puttur¹, Sameena Pathan², Vikash Kumar Jhunjhunwala³, Tanweer Ali¹

Affiliations

¹ Department of Electronics and Communication Engineering, Manipal Institute of Technology, Manipal Academy of Higher Education, Manipal 576104, India.
² Department of Information and Communication Technology, Manipal Institute of Technology, Manipal Academy of Higher Education, Manipal 576104, India.
³ Department of Electrical and Electronics Engineering, Manipal Institute of Technology, Manipal Academy of Higher Education, Manipal 576104, India.

Abstract

Advancement in smartwatch sensors and connectivity features demands low latency communication with a wide bandwidth. ISM bands below 6 GHz are reaching a threshold. The millimeter-wave (mmWave) spectrum is the solution for future smartwatch applications. Therefore, a compact dual-band antenna operating at 25.5 and 38 GHz is presented here. The characteristics mode theory (CMT) aids the antenna design process by exciting Mode 1 and 2 as well as Mode 1-3 at their respective bands. In addition, the antenna structure generates two traverse modes, TM₁₀ and TM₀₂, at the lower and higher frequency bands. The antenna measured a bandwidth (BW) of 1.5 (25-26.5 GHz) and 2.5 GHz (37-39.5 GHz) with a maximum gain of 7.4 and 7.3 dBi, respectively. The antenna performance within the watch case (stainless steel) showed a stable |S₁₁| with a gain improvement of 9.9 and 10.9 dBi and a specific absorption rate (SAR) of 0.063 and 0.0206 W/kg, respectively, at the lower and higher bands. The link budget analysis for various rotation angles of the watch indicated that, for a link margin of 20 dB, the antenna can transmit/receive 1 Gbps of data. However, significant fading was noticed at certain angles due to the shadowing effect caused by the watch case itself. Nonetheless, the antenna has a workable bandwidth, a high gain, and a low SAR, making it suitable for smartwatch and IoT applications.

Keywords: IoT; SAR; dual-band; link margin; millimeter wave antenna; smartwatch.

Grants and funding

This research received no external funding.