This Technical Report specifies a guideline for improvement of signal loss by using noise suppression materials (hereafter referred to as NSMs) for FPCBs. This Technical Report also indicates a measuring method of signal loss variations of FPCBs using NSMs using network analyzer equipment. In addition@ this method only measures the value of the signal loss variation by using NSMs for FPCBs. This report@ however@ neither determines nor indicates the structure or material of FPCBs.