Characterization of Single Vehicle Ignition Noise at 4 GHz and Related Susceptibility Analysis of a Satellite Receiving System

This paper describes the methodology and results of measurements performed to characterize the radiated emissions from a modern automobile V-8 ignition system. The overall radiated pulse shape and frequency distribution are described. Sample calculations are performed to determine the effect of these emissions on a 500 MHz communi­ cations channel in the 3.7 to 4.2 GHz frequency band. The overall pulse shape can be best described by a decaying exponential. For frequencies greater than 1 kHz the pulse produced a continuous monotonically decreasing frequency distribution which has a slope of 6 dB per octave. The resultant spectral amplitude distribution in the 500 MHz band between 3.7 and 4.2 GHz is nearly flat. The time domain representation of the signal present in the 500 MHz bandwidth between 3.7 and 4.2 GHz is a critically damped exponential pulse with a rise time of 0.37 ns and a fall time on the order of 2.1 ns. Measurements to determine the coupling effects of ignition emissions to a satellite earth station 42-foot full performance antenna are described. The results of these measurements show that the antenna, in its near field, has a very small effective area.