[email protected] writes: >Hi, > >>Ed Price said: "I have heard of active cancellation equipment which can >generate a phase shifted image of the offending signal and locally >radiate >this signal so as to create a limited "null" zone. How big of a null >zone, >the uniformity of cancellation, the stability and agility of the >cancellation and the cost/complexity of the equipment are all unknown to >me. > >>I wonder if any in our group has every tried active cancellation?" > >A friend of mine told me a few years ago that the active cancellation >technology was successfully applied in Acoustics. IF it is true, I guess >the difficulty to transplant it to Electromagnetic is that Acoustic field >is scalar, whereas EM fields are vectors. > >Best Regards, >Barry Ma > Barry,
I have actually spent some effort in looking at active cancellation for acoustical problems. It really does work and is quite amazing. I have also seen it applied to mechanical vibration problems. Obviously, in both cases, there are considerations and it may not always work as well as one would prefer. I even recall there was once some interest by various military outfits in EM cancellation. Can't recall enough to comment otherwise. I will say that if someone knows of such a system or product, I surely would like to look at it to help solve some problems with my lab. Regards, Scott [email protected] --------- This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to [email protected] with the single line: "unsubscribe emc-pstc" (without the quotes). For help, send mail to [email protected], [email protected], [email protected], or [email protected] (the list administrators).
