A circular-shaped two-slot foam-based flexible UWB antenna for medical applications

The biomedical industries have recently shown a great deal of interest in the study of flexible wireless devices. Wearable antennas are vital in medical applications as they enable continuous, real-time monitoring of patient health. In this context, a circular-shaped two-slot flexible ultra-wideband microstrip antenna is presented for use in the medical field. An inexpensive, lightweight flexible foam substrate material of 2 mm thickness with dielectric constant 1.07 and copper foil of 50 microns for patch is proposed in the fabrication of antenna. This paper presents a circularly shaped antenna of size $$48\times 36 {\text{mm}}^{2}$$ with patch radius of 12 mm and detailed analysis of bending, on-body and SAR with actual measurement. A good matching is observed between measured and simulated results with the bandwidth of 10 GHz over the ultra-wideband operating frequencies of 3.1–10.7 GHz. The slot and stub added into geometry has resulted into the total gain of 4.7 dB, with good impedance matching. An extensive SAR analysis for 1 and 10 g tissue has been carried out with average SAR of 0.0215 W/kg and 0.0138 W/kg respectively and found below the safety limit as prescribed by IEEE.