As a little funny demo, go to this: http://www.falstad.com/mathphysics.html select 'Electrodynamics' select Electromagnetic waves in a waveguide Play with various frequencies and vary the TEM (wave mode) and you will get a glimpse of the mystery of microwaves. ( I suppose many Technetters work daily with EM simulations, someone may have better illustrations, e.g. the charge transportation in a copper plane with various thickness, number of vias etc.) Inge ----- Original Message ----- From: "Inge" <[log in to unmask]> To: "TechNet E-Mail Forum" <[log in to unmask]> Sent: Thursday, July 30, 2009 11:48 PM Subject: Re: [TN] Hashing-Out Hatching > Well, what was the conclusion of this discussion from start? As I'm pretty > involved in microwave design, but I could not find the red thread. One > cannot generalize about Faraday cages, vias, ground planes etc. The > behaviour of electromagnetic waves is a spectrum of possibilities. Can't > enough marvel when I see simulations of EM transportation through coax > lines, through dielectrics, through metals, how radiation can creep > unexpected ways despite metal shields, how ground planes suddenly works as > antennas etc. Working from Megawatts to nanowatts, from travelling wave > tubes to one-chip radar TRMs, you learn that this area differs a lot from > other fields in that common rules are not always practicable. So, what was > the come-out of the discussion. I am really curious. > > Inge > > ----- Original Message ----- > From: "Craig Cullum" <[log in to unmask]> > To: <[log in to unmask]> > Sent: Thursday, July 30, 2009 4:32 PM > Subject: Re: [TN] Hashing-Out Hatching > > > Graham, you're probably going to start feeling that you are being dumped > on (smile). > I regret to say that this is a practice we use here to better our chances > of > passing emissions testing. > > Craig Cullum, Engineering Technologist, AMTELCO > e: [log in to unmask] > [log in to unmask] > f: 608 838 8367 > v: 608 838 4194, or 4197, x128 > > Please visit us at www.amtelco.com > >> -----Original Message----- >> From: TechNet [mailto:[log in to unmask]] On Behalf Of Kenneth Wood >> Sent: Thursday, July 30, 2009 9:03 >> To: [log in to unmask] >> Subject: Re: [TN] Hashing-Out Hatching >> >> Actually that is the HDI method that is becoming more and more popular. >> Via-in-pad, internal routing and external GND planes. >> Ken >> >> -----Original Message----- >> From: TechNet [mailto:[log in to unmask]] On Behalf Of Graham Collins >> Sent: Thursday, July 30, 2009 9:58 AM >> To: [log in to unmask] >> Subject: Re: [TN] Hashing-Out Hatching >> >> Ha... We had a designer at one time who thought that surface traces were >> bad, very bad. So every pad for every part had a short trace that >> immediately went to a via and the signal was routed to an inner layer. >> Seriously. That guy needs your doctor... >> >> regards, >> - Graham Collins >> >> -----Original Message----- >> From: TechNet [mailto:[log in to unmask]] On Behalf Of James Head >> Sent: Thursday, July 30, 2009 10:50 AM >> To: [log in to unmask] >> Subject: Re: [TN] Hashing-Out Hatching >> >> > Gary brought me back to the days when, just for kicks, I would take >> > other >> > guy's designs and remove all of their vias, just to prove I could do >> > it. >> I've >> > gotten help, I'm cured, a thousand vias is nothing anymore. >> >> You should pass me the details of your doctor - I always spend a little >> time >> at the end of a project going through and trying to eliminate vias if I >> can >> as I see everyone of them as a potential failure point - and it's very >> satisfying to re-run the drill report and see the hole count drop! >> >> Mind you I'm not obsessive though. I worked with one relatively >> inexperienced PCB designer once who spent a whole week designing a power >> and >> deflection PCB for a televison and managed to do it all without any vias >> or >> wire jumpers. Unfortunately his design would never have worked with >> segregation between the primary and secondary sides of the transformer >> and >> 0.3 mm traces carrying high voltages and currents! >> >> James >> ******************************************************** >> >> The information transmitted is intended only for the person or entity to >> which it is addressed and may contain confidential and/or privileged >> material. 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