To use a nuclear explosion as an effective EMP weapon rather than just causing some unexpected trouble, requires some careful control of the circumstances, and the radio waves produced, like the heat and light, obey the inverse square law when you get out of the near field, just like any other source. Considerable study has gone into this, although most of the results are not published
Te conclusion is that a large bomb, say 1 megaton, detonated at altitude certainly can have continent wide effects.
This graph is from this weighty tome but depicts the electric fields at the earths surface, in kilovolts per metre, at various ranges from ground zero from a 1MT detonation from outside the atmosphere, at ~ 800km altitude.
To put that into scale, a few kV/m can damage electronics with exposed wiring acting as an accidental antenna, and a interference at the level of volts per metre stops much domestic electronics until the source is removed. A typical radio signal might be 1-10 micro volts per metre.
as you see, disruption to non-shieded electronics out to a few thousand km may be expected.
The introduction to EMP Engineering Practices Handbook, Nato File 1460-3, (admittedly now rather dated), has some typical numbers, for other situations.
To use a nuclear explosion as an effective EMP weapon rather than just causing some unexpected trouble, requires some careful control of the circumstances, and the radio waves produced, like the heat and light, obey the inverse square law when you get out of the near field, just like any other source. Considerable study has gone into this, although most of the results are not published
Te conclusion is that a large bomb, say 1 megaton, detonated at altitude certainly can have continent wide effects.
This graph is from this weighty tome but depicts the electric fields at the earths surface, in kilovolts per metre, at various ranges from ground zero from a 1MT detonation from outside the atmosphere, at ~ 800km altitude.
To put that into scale, a few kV/m can damage electronics with exposed wiring acting as an accidental antenna, and a interference at the level of volts per metre stops much domestic electronics until the source is removed. A typical radio signal might be 1-10 micro volts per metre.
as you see, disruption to non-shieded electronics out to a few thousand km may be expected.
The introduction to EMP Engineering Practices Handbook, Nato File 1460-3, (admittedly now rather dated), has some typical numbers, for other situations.
