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Electronic Warfare and Radar Systems Engineering Handbook | |||
EMP / AIRCRAFT DIMENSIONS An aircraft flying in the vicinity of an electromagnetic pulse (EMP) acts like a receiving antenna and picks up EMP radiation in relation to size like a dipole (or half-wavelength dipole). The electromagnetic pulse spectrum decreases above 1 MHz as shown in Figure 1, so an F-14 aircraft that is an optimum ½ wavelength antenna at ~8 MHz will pick up less EMP voltage than a B-52 or an aircraft with a trailing wire antenna. A rule of thumb for the voltage picked up is : VEMP = 8.1 volts/ft times the maximum dimension of the aircraft in feet This rule of thumb was generated because a single linear relationship between voltage and aperture seemed to exist and compared favorably with more complex calculations for voltage picked up by various aircraft when subjected to EMP. Table 1 shows various aircraft and the frequencies they would be most susceptible to, using f = c/8, where 8 matches the selected aircraft dimension for maximum "antenna reception effect". This should be a design consideration when trying to screen onboard avionics from the effects of EMP. The following is a partial listing of aircraft types vs identifying prefix letters (several are used in Table 1):
Table 1. AIRCRAFT DIMENSIONS AND EQUIVALENT ANTENNA APERTURE Table of Contents for Electronics Warfare and Radar Engineering Handbook | |||
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RF Cafe began life in 1996 as "RF Tools" in an AOL screen name web space totaling 2 MB. Its primary purpose was to provide me with ready access to commonly needed formulas and reference material while performing my work as an RF system and circuit design engineer. The Internet was still largely an unknown entity at the time and not much was available in the form of WYSIWYG ... All trademarks, copyrights, patents, and other rights of ownership to images and text used on the RF Cafe website are hereby acknowledged. My Hobby Website: AirplanesAndRockets.com
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