Magnetic Affects on Vehicle Electronics
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defrosterDefrosters have large currents running through them, thus creating a magnetic field. Defrosters have a wire running the length of the car to deliver the Tests were performed to find out how the magnetic field will affect the location of a compass in a vehicle. Tests were performed on two vehicles. A Chrysler Concord and an Isuzu Rodeo. Each had a different style of defroster in the rear window. Also, a theoretical model will be used in order to predict future magnetic strengths of defrosters by the amount of current going through it. The result from the testing of vehicles has proved that there are large magnetic fields attributed to the defroster running. These fields only appear close to the window, and become almost negligible at a few feet away. This is becoming more of an issue as a result of some European vehicles providing defrosters in the front windshields of vehicles. This could have an affect on the compass that we provide to the makers of these vehicles. The measurements of the vehicles took place at nine different spots on the rear windshield. Four of the measurements were taken at the corners, and 4 were taken at the mid points of the edges. And the ninth measurement was taken in the middle of the windshield. For each of the vehicles the current and voltage was measured going through the defroster. The field strength was measured on all three of the axis, with the z-axis being perpendicular to the window. The measurements were taken with a 3-axis gauss meter. Measurements were taken at different distances from the surface of the window. In order to find the affects of the defroster, measurements were taken of the ambient field at certain distances away. Then the measurements were taken when the defroster was on at the same distances. Also a theoretical model was created so that one could predict the affects of any defroster. The Isuzu rodeo had the following results. The current going through this defroster was 15.61amps. The voltage was 12.48. The result of the testing of the Isuzu Rodeo can be seen below for the distance of .75”, the rest of the distances and their values can be seen in Appendix A. Table 1 – Isuzu Rodeo at .75” 
These are the results of the Isuzu Rodeo. As you can see the strength of the magnetic field even out to over a foot is very large. A field of almost 300mG is very strong. That, in most places of the world, would make the field the compass sees, at least twice as big. Anything within 3 ft of this style of defroster would cause too many problems. That, in most places of the world, would make the field the compass sees, at least twice as big. The results of the Chrysler Concord will now be looked at. The current going through the defroster is 19.37amps. The voltage is 12.73. The Concord had measurements taken at the following distances: .75”, 4”, and 8.75”. The results of the measurements can be seen in Tables 6 – 8, which are in Appendix B. Table 2 – Chrysler Concord at .75” 
The results from the Chrysler Concord are not as bad as the Isuzu Rodeo. Yet, the defroster will still have an affect on the compass if it is close enough. The Concord has a different style of defroster on it than the Rodeo does. The defroster on the Concord has two wires that go vertically in the window, thus making the current going through the windshield a lot less. Essentially this is creating parallel current paths for the current to flow through, thus dividing the current by three, since the resistance is the same throughout the defroster. This style of defroster reduces the current flow through the windshield to about 8 amps, instead of the 19.37 that is sent to the defroster. One theoretical defroster model was created. This model only simulates an infinite sheet that is at a certain width. The width used is .55 meters. The flux strength was modeled using the infinite sheet current conductor equation. Directory: ~pribeiro -> courses -> engr302 -> Samples Samples -> Cell Phone Antennas: a look at the history and design of vhf antennas ~pribeiro -> Transmission Power Quality Benefits Realized by a smes-facts controller ~pribeiro -> The magician's nephew engr302 -> Wireless Communications: Past, Present, and Future ~pribeiro -> Michael Ward "Always winter, and never Christmas" ~pribeiro -> The Last Battle ~pribeiro -> By C. S. Lewis a sermon preached in the Church of St. Mary the Virgin, Oxford,Autumn, 1939 Download 0.51 Mb. Share with your friends:
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