Tech Notes
EMI Described
Electromagnetic interference is an unwanted by-product of the electronic age. EMI problems started shortly after Mr. Marconi put his second radio transmitter on the air, and the two radios began to interfere with each other. The problem has steadily become more complex and difficult with every new technical advance in electronics. The vast quantity of electrical devices in use today and new levels of sensitivity in electronic circuits means that every electrical device has the potential to cause interference or to be interfered with. Just a few years ago the EMI spectrum was defined to be within the range from 100 KHz to 35 MHz; presently it is defined to be within the range from 10 KHz to over 10 GHz (10,000,000,000 Hz), with special cases pushing these limits. Designing effective systems to eliminate interference requires an excellent knowledge of high energy and broad spectrum interaction. Skills in electronic engineering, mechanical engineering, materials science plus many years of experience are required to design effective EMI filters.
National defense is the top priority in ours and most other countries. Today's complex weapons systems which are a part of that defense depend heavily on electronics to direct and control them. These systems are very sensitive to Electromagnetic Interference. A failure in one of these systems could have serious effects on all of us. Building filters to achieve Electromagnetic Compatibility (EMC) in the military environment requires other capabilities in addition to basic filter design. In terms of reliability, the filter must meet the same requirements as the systems they go in. This is not a simple task since size, weight, performance, cost and time are always in confliction with each other.
