This study employs a simple measurement methodology that is based on the de-convolution of a square test stimulus to measure the transmission characteristics of the human body channel in an electrostatic-coupling intra body communication system. A battery-powered square waveform generator was developed to mimic the electrostatic-coupling intra body communication system operating in the environment of the ground free. The measurement results are then confirmed using a reliable measuring method (single tone) and spectral analysis. The results demonstrate that the proposed measurement approach is valid for up to 32.5MHz, providing a data rate of over 16Mbps.