The effect of wireless electronics in the hospital increased. Research conducts some hospitals shows the risk of the radio frequency interference with the other equipment in hospital. Signals coming from wireless devices can cause malfunction to some medical equipment such as MRI, CT SCAN and X-ray. To solve this problem, ISM band detection system is used to detect radio frequency from mobile phones. The system consists of three LEDs which shows the level of the emissions from the risk to the safe. Meaner line antenna designed to operate at frequency of 2.4GHz with a help of CST studio software. The hardware part is used microcontroller to check and compare the results from the software.