The inter-system electromagnetic environment is external to the system and
may be encountered during an operational mission. During a combat mission the
aircraft or missile must operate first within the environment of an airfield,
ship or launching pad; second in the environment created by other aircraft,
missiles or guidance systems; and finally during attack, in the environment
created by radiation from hostile air defense systems and high power microwave
(HPM) weapons. The aircraft or missile may also be illuminated by a high
altitude electromagnetic pulse (HEMP) event prior to or during a sortie.
Operational experts should characterize the inter-system environment for the
designer by measurement or prediction prior to establishing specifications for
the E3 control program that is to be prepared for the platform/system
procurement This has been addressed in general terms in specification
In addition, MIL-HDBK-235 also provides detailed information on potential
operational electromagnetic environments. Portions of that handbook are
classified, so it is essential that those responsible for developing and
implementing the design to operate in this environment have the appropriate
access based on their "need-to-know."
It usually takes some time to gel uncleared personnel the appropriate
security access under the Department of Defense Industrial Security Program. DoD
5220.22M, Industrial Security Manual For Safeguarding Classified Information,
spews out the corporate and individual security requirements necessary to obtain
access to this and other DoD classified documents. Since there are important
restrictions, it is essential that any subcontractor supporting the primary
contractor program be appropriately cleared as well. "Working around" security
requirements will not be tolerated, so access requirements throughout a design
and production procurement/project should be established as soon as possible
when assembling the total team for the job.
presents a spectrum plot that might be anticipated by an aircraft or missile
in the vicinity of an airfield or onboard a Navy vessel. The levels are a
result of the High Intensity Radiated Fields (HIRF) as defined in
It is this external environment that normally establishes the basic
requirements for cable shielding to protect sensitive electronics.
When the missile or aircraft skin is made of a conductive material, the
internal environment will be reduced by the attenuation of the skin based upon
its conductivity, permeability and the size and number of penetrations.
Non-conducive composites will normally not be as effective in shielding
electronics from the electromagnetic environment. This would require additional
shielding of cables and equipment.
Design engineers must design cable systems with sufficient built-in shielding
protection to preclude the electromagnetic environment from interfering with the