Figure 5
From: Enabling Covert Body Area Network using Electro-Quasistatic Human Body Communication
(a–d) QS Field distributions for different configurations of the transmitter device. (a) In mode 1, voltage drop across the signal plate of the Standalone shielded transmitter and earth ground is maximum (VS ~ VDD) as there is no direct path from the signal plate to the earth ground. (b) In mode 2, as an attacker approaches with a probe towards the shielded transmitter, it receives negligible voltage as no current flows due to the high impedance path from signal to ground. Hence, standalone shielded transmitter does not leak. (c) In mode 3, Human body coupled to the transmitter device for EQS-HBC provides a low resistance closed path to ground; hence higher voltage received by the attacker (VQSL) (d) Summary of the 3 modes – In absence of the human body, all the voltage drop (VS) occurs across the signal terminal and ground and the attacker does not pick any signal (mode 2). In presence of the human body, a close-by attacker (touching the shield) can obtain a high signal. Hence, in spite of shielding, the EQS-HBC transmitter device leaks.
