Design and Implementation of a Portable Mobile Phone Jammer for Restricted Zones using 555 Timer

Mobile phones, while integral to modern communication, pose significant challenges in sensitive and controlled environments such as examination halls, where they can be misused for cheating or cause unnecessary distractions. This research presents the design and implementation of a portable mobile phone jammer intended to restrict mobile communication within a defined area. This research presents the design and implementation of a portable mobile phone jammer intended to restrict mobile communication within a defined area. The proposed system targets major cellular frequency bands including GSM (900/1800 MHz), 3G (2100 MHz), and 4G LTE, using a combination of voltage-controlled oscillators, RF amplification circuits, and directional antennas to emit interference signals. The device is compact, battery-powered, and optimized for shortrange deployment, making it ideal for temporary enforcement of mobile restrictions in academic settings. Experimental evaluation demonstrates effective jamming within a radius of up to 10 meters, without affecting surrounding areas. This work provides a cost-effective and efficient solution to preserve the integrity and silence of examination halls, with potential applications in other restricted zones requiring communication control.