Electromagnetic pulses (EMP) are powerful bursts of energy that can occur at various altitudes, ranging from one mile or less above the Earth's surface (known as a surface burst EMP or SBEMP) to twenty miles above Earth (known as high-altitude EMPS, or HEMP). Most HEMPs fall within the frequency ranges of 100 kilohertz to 10 megahertz. The energy of the electromagnetic pulse is composed of several direct current frequencies up to a certain upper limit, which depends on the source. According to Maxwell's equations, a pulse of electrical energy is always accompanied by a pulse of magnetic energy.
EMPs can be caused by both man-made and natural effects, as well as by weapons. The first recorded damage caused by an EMP was the solar storm of August 1859, also known as the Carrington event. Electromagnetic weapons cause incorrect operating effects on their targets, mainly by inducing pulses in the internal or external signal lines of digital devices and thus interrupting the original digital signal. The pulse voltages used to produce the EMP are usually high-speed pulses that peak within a few nanoseconds and then decline for a longer period.
Andrei Sakharov, in the Soviet Union, conceived as early as 1951 the concept of a flow compression generator with explosive pumping to generate a non-nuclear electromagnetic pulse, but countries continued to work on the classification of non-nuclear EMPs until similar ideas emerged in other countries. The pulses of a controlled switching circuit are usually in the form of a rectangular or square pulse. They usually send a pulse to any electrical connection present, in addition to radiating a pulse of energy. To achieve the pulse frequency characteristics necessary for optimal coupling to the target, wave-forming circuits or microwave generators are added between the pulse source and the antenna.
The high-voltage pulse produced by the generator is applied as an electromagnetic field to the device under test by means of an antenna. Induced pulses have much lower energy than threat pulses, so it's more practical to create them, but they're less predictable. A high-altitude electromagnetic pulse (HEMP) weapon is a NEMP warhead designed to detonate high above the Earth's surface. A pulse of electromagnetic energy typically comprises many frequencies, from a very low limit to an upper limit, depending on the source.
Most electromagnetic pulses have a very sharp edge of attack and build up quickly to their maximum level.