This study proposes and evaluates a novel implantable antenna testing method using a tissue gel phantom combined with a living human subject to simulate realistic implantation conditions. The gel phantom, shaped by 3D-printed molds and composed of water, sugar, salt, and agar, enables antenna performance analysis through channel gain and Received Signal Strength Indicator (RSSI) measurements in mobile environments. By incorporating human subjects, we capture channel gain variations in dynamic conditions influenced by design, gain, implantation site, and subject movement. This novel setup allowing rotational movement and untethered Bluetooth Low Energy (BLE) packet analysis reveals a previously undetectable 20 dB difference between line-of-sight and non-line-of-sight scenarios, highlighting the limitations of traditional bench-top phantoms.