Murtini Murtini, Nurhayati Nurhayati, Usman R. Iman, Fitri Y. Zulkifli, Dewiani Dewiani, Lilik Anifah
Non-contact vital sign monitoring using radar technology has become increasingly important in modern healthcare, as it enables continuous physiological measurements without direct contact with the skin, minimizing patient discomfort and the risk of infection. To address this need, this study presents the design and analysis of a 24 GHz microstrip antenna array developed for a radarbased vital sign monitoring system. Array configurations consisting of one to five circular patch elements were analyzed to optimize the reflection coefficient, directivity, and radiation characteristics, with the aim of achieving high sensitivity, compactness, and safety for biomedical radar applications. Simulation results show that the four-element array achieves optimal performance, with a reflection coefficient of −39.27 dB, directivity of 5.29 dBi, and a bandwidth of 1.35 GHz at 24 GHz. To evaluate electromagnetic safety, Specific Absorption Rate (SAR) analysis using a three-layer human tissue model (skin, fat, and muscle) resulted in values of 0.159 W/kg (1 g) and 0.022 W/kg (10 g), both within ICNIRP and FCC limits. Additionally, bending simulations with a radius of curve at 10 mm, 20 mm, 30 mm and 40 mm showed stable impedance matching and minimal frequency variation, demonstrating high mechanical flexibility. On the whole, the proposed antenna exhibits high gain, reliable performance, and safety compliance, making it suitable for integration into portable radar-based medical devices for continuous, contactless monitoring of heart rate and respiration. © 2026, Electromagnetics Academy. All Rights Reserved.
Department of Electrical Engineering, Universitas Negeri Surabaya, Surabaya, 60231, Indonesia; Department of Electronic Engineering, Hanyang University, Seoul, 04763, South Korea; Department of Electrical Engineering, Universitas Indonesia, Depok, 16435, Indonesia; Departement of Electrical Engineering, Faculty of Engineering, Universitas Hasanuddin Gowa, South Sulawesi, Indonesia
