A how-to on making an EMP jammer from JunezRiyaz, project instructables here:
An electromagnetic pulse (EMP), also sometimes called a transient electromagnetic disturbance, is a short burst of electromagnetic energy. Such a pulse may occur in the form of a radiated electric or magnetic field or conducted electrical current depending on the source. EMP Jammer is a device capable of generating a transient electromagnetic disturbance that radiates outward from its epicenter, disrupting electronic devices.
Check out the video after the break.