Simulation-based Design of a Compact Wearable Antenna for Microwave Imaging of Bone Fractures in Osteoporotic Patients

Abstract

Osteoporotic bone fractures require safe, repeatable monitoring approaches, particularly when repeated exposure to ionising radiation is undesirable. This study presents the simulation-based design of a compact wearable microstrip patch antenna for microwave assessment of bone-fracture conditions in osteoporotic patients. The antenna incorporates an elliptical tapered radiating patch and a microstrip feed structure on a flexible Rogers RT/duroid 5880 substrate, selected to support conformal placement near the lower limb. The proposed configuration was evaluated over the 1-6 GHz frequency range using CST Studio Suite and ANSYS HFSS. A multilayer lower-limb tissue model comprising skin, fat, muscle and osteoporotic bone was developed to examine antenna performance in proximity to biological tissue. Fractured, soft-callus, healed and healthy bone conditions were represented by changes in relative permittivity and conductivity. The simulated response showed impedance-matching behaviour, with return loss below -10 dB over the reported operating band and a voltage standing wave ratio below 2 within the useful matched region. The peak simulated gain was approximately 5.7 dBi. Specific absorption rate analysis at 2.45 GHz and 100 mW input power produced a maximum value of 1.8 W/kg in the tissue model. Differences in reflected microwave response were observed between fractured and healed bone models owing to changes in dielectric contrast. These results suggest that the proposed wearable antenna may warrant further investigation as a non-invasive microwave sensing element for bone-fracture monitoring. Fabrication, experimental validation and testing on realistic physical or clinical models are required before practical biomedical use can be established.