[Amps] placement of RF choke bypass cap.

[Gary Schafer]

> -----Original Message-----
> From: amps-bounces at contesting.com [mailto:amps-bounces at contesting.com]
> On Behalf Of Bill, W6WRT
> Sent: Thursday, March 18, 2010 10:18 PM
> To: amps at contesting.com
> Subject: Re: [Amps] placement of RF choke bypass cap.
> 
> ORIGINAL MESSAGE:
> 
> On Thu, 18 Mar 2010 19:03:20 -0400, "Gary Schafer"
> <garyschafer at comcast.net> wrote:
> 
> >
> >But it is relevant. It is the same thing. He has part of one surface
> >conducting RF between the two terminals. Measuring on the other side of
> the
> >sheet shows no current on the other side.
> >If you think about it the sheet of copper or your chassis, as far as RF
> is
> >concerned, is two very thin sheets with an insulator in the middle. The
> >insulator comes about because of skin effect.
> >
> >It is no different than the shield on a coax cable. No RF energy can
> >penetrate the shield because of skin effect.
> 
> REPLY:
> 
> Think about this:  If you made a dipole out of flat bar instead of
> wire, you could feed just one side of the bar and have an antenna that
> radiated in only one direction. The other side of the bar would shield
> against radiation in that direction.  This would make a great driven
> element for a yagi wouldn't it? No reflector needed.
> 
> There must be a reason why they don't do that.
> 
> 73, Bill W6WRT

What do you think happens when you use a tube for an antenna element?
The whole element is charged. If you connect the feed line to only the front
side of the element there is still current on the back side of it.
How do you think the current gets around to the other side?

But try to measure the current on the inside of the tube. You will find
none!

73
Gary  K4FMX