Am Do 18. September 2008 schrieb Andy Green: > There is definitely a story waiting to be uncovered here. On my GTA02 > A5 "skelephone" that is just a PCB, I replaced plastic GSM antenna with > "random piece of wire". The buzz comes fine. "Over the air" > contamination does not involve antenna radiation pattern then, it is > suspicious. It means PCB inherently couples "something" "somewhere" > before antenna. I keep going back to power rail-borne contamination but > it doesn't fit with beads doing something on headset nets.
Not "doing something" but actually stopping noise completely, according to Len and Candy. We also heard noise is stopped by connecting external GSM-antenna, as well as by removing JK4401, and I managed to induce noise by "alien" RF fed to the phone (actually near hs-jack JK4401) by using some test-phone placed near to it. Power-rail has been examined by me for a whole day more than 2 months ago: result negative. So I don't exactly get it what's your conclusion from replacing plastic-GSM-ant by a "random piece of wire". Especially I don't know about "antenna radiation pattern" of this wire and how it should differ from the one of plastic-antenna. Actually probably nobody can tell exactly about the particular characteristics incl radiation pattern of any antenna setup, until you actually did decent research on a prototype. That's the main culprit for RF-design resembling black magic rather than logic-based EE. /jOERG
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