YAGI Antenna Design for Signal Phone Jammer
  Mobile phone is one of the most widely used today in mobile communications. This technology is very useful for communication but this raises several problems in a situation where silence is required such as in libraries, places of worship, classrooms and others. Mobile phone jammer is a device that used to block the incoming signal to a mobile phone from the base station. If the mobile phone jammer is turned on then it can not form the incoming or outgoing calls even sms. In this research, we designed a Yagi antenna (900MHz) to expand the range of jamming because Yagi has a great gain. Results of impedance by gamma match are 50.16 Om. Obtained the value of VSWR Yagi is 1.46:1 and jamming distance that can be taken approximately 16 meters, It is different from the jamming distance of helical antenna on a mobile phone jammer itself is about 4 meters. 
Y. Fitriyani, A. B. Mutiara, R. Refianti
cs.OH