Simulated in Vivo Implantable Antenna Measurements in Gel Phantoms and Human Subjects: Channel gain, directivity, and received signal strength indicator [Bioelectromagnetics]

Conventional radio-frequency phantoms for implantable antenna testing fail to replicate the dynamic electromagnetic and biomechanical complexities of in vivo environments. These static phantoms, while reproducible, overlook critical factors, such as tissue heterogeneity, implantation depth variability, and motion-induced transmission fluctuations, leading to unreliable performance estimates for deeply implanted medical devices. To address this, we propose a hybrid experimental method combining a customizable tissue-mimicking gel phantom (fabricated using water, sugar, salt, and agar shaped in 3D-printed molds) with a living human subject. By employing a mobile setup with rotational freedom, we capture real-world channel gain and untethered received signal strength indicator (RSSI) variations, revealing a 20-dB disparity between line-of-sight (LOS) and non-LOS (NLOS) conditions, a critical metric undetectable with conventional bench-top phantoms. This approach bridges the gap between controlled lab testing and clinical realism for implantable antenna design, allowing surgery and animal-free implantation estimates.