Transcutaneous power and signal transmission system are useful for artificial hearts. The signal transmission system is important to control the implanted device and to monitor the inside condition. They do not have lines penetrating through the skin. The signal transmission coils are set on the power transmission coils. We have proposed integrated power and signal transmission system utilizing eight-figure coils. Using the signal transmission coil pairs we have proposed, we studied through measurements and experiments the communication area for implantable signal transmission system with a ferrite chip core.