Through the characterization of a fabricated PIN diode with the aid of a simulation, a structural guideline for a reconfigurable antenna is developed. By comparing the conductivity with the equivalently normalized power, an optimal intrinsic channel length is determined. Simulation data show that a high carrier concentration is sustained along both the vertical and lateral directions in the intrinsic region. Due to the simple fabrication process and the controllability of the exposed channel region as well as the high carrier concentration with good uniformity, the proposed PIN diode is a viable candidate for a future antenna.