Legality

• The FCC outlawed the use of signal jammers, so information about how to make a homemade version is not widely publishable. However, components of the device and information on their function are available.
  
  

Antenna

• Cell phone jammers need an antenna to transmit the offending signal. In smaller products the antenna is an internal component, housed within an electrical cabinet, while external antennas are used for longer range.
  
  

Electrical Components

• The interference signal is generated by an oscillator. A tuning circuit channels the required voltage to the oscillator, which sets the limits for the jammer broadcast's frequency. The circuit also contains a noise generator that emits random electronic output in the boundaries of the set frequency range. The output is bolstered by RF amplification to make it high enough to jam the specific signal.