EMP (Electronic Magnetic Pulse) is a significant threat in our modern era.  EMP creates a powerful electromagnetic field capable of short-circulating a wide range of electronic equipment, particularly computers, satellites, radios, radar system, signal equipment and even civilian infrastructure.

Since EMP is electromagnetic energy traveling at the speed of light, all of the vulnerable electronic equipment in the detonation zone could be affected simultaneously. The destructive power is enormous enough to damage subterranean cables at distances of several hundred kilometers or more.

When we talk about the EMP, it can classified into three types which is LEMP, NEMP, NNEMP/IEMI

Impact of HEMP

Powerful electromagnetic pulses attack a wide range of instantaneous locations
  • In the event of a high-altitude nuclear explosion (HOB≥30 km), a powerful HEMP affects the range of approximately 600 km above the ground
  • Damage most of the public low-power distribution networks, telecommunications networks, electricity, and electronic devices
  • Extended absence of each type of telecommunication service and public power supply simultaneously
The transformation of society as a whole into a primitive pastoral life
  • Most functions such as administration, finance, transportation, commerce, sewage, medical care, distribution services, etc.
  • Food, medicine, manufactured goods, and fuel are gradually depleted due to the inability of major industrial systems to operate
  • Modern civilization is transformed into a primitive rural life, but the country and society cannot recover within a short period of time
Information Society Foundation and the absence of Information and Communication Services : Panic
  • Most of the state-run system, social and resource management functions are paralyzed for a long period of time
  • Most of the command system and interconnection functions of the national defense and security systems have been lost
  • No public communication service and no information service available


Initial HEMP Medium-term HEMP Late HEMP
Maximum Field Strength Number kV to 50kV/m Number 10V/m to 100V/m A number of mV/m to 40mV/m
Maximum Total Field Strength Reached Time 4.8ns 4.8ns 160ms
Threats Electromagnetic field Electromagnetic field Magnetic field
Threats Split face Horizontal (Vertical) Horizontal
Energy Influence 0.114 J/m2 0.0133 J/m2 -
Maximum pulse rise/sustaining time 2.5ns/23ns 2.5ns/110 µs 0.9s/150s
Interference Duration (10% to 90%) 0.05ns/100 µs 0.2ns ~ 100ms 0.5s ~ 1,000s
Major Damage Target Influence on all electrical, electronic, device, and small short conductors L ≥ Mainly affected by large systems greater than 1 km L ≥ Part of 2Km power distribution network telecommunication network
HEMP main generation factor γ-ray Neutrons scattering MHD Effectiveness

HEMP Protection Performance Verification

SE (Shielding Effectiveness) Test
  • Require level for shielding effects : MIL STD 188-125-1&2
  • Blocking with steel (Fe) or copper (Cu)
  • Perform under the normal operating conditions of all facilities when testing shielding performance
Electromagnetic shielding performance criteria (SE)
  • SE = Threat level (50 kV/m) – Resistance level (10V/m) + Safety margin (8 dB) = 82 dB
PCI (Pulsed Currvent Injection) Test
  • Pulse current applied to external cables to verify that the amount of flow into the shield wall is within acceptable limits
  • Pulse type: Short Pulse, Intermediate Pulse, Long Pulse
CWI (Continous Wave Immersion) Test
  • Test to examine the radiation continuous wave (CW) field on the external surface of the electromagnetic barrier, measure the response field inside the electromagnetic barrier, and identify shielding defects and improperly protected opening intrusion points