Topband: QST Jun 06 RX Loop

[k3bu at optonline.net]

Tom is confusing Faraday shield with Electrostatic shield and whole reasoning that the grounded shield of small loop antenna is THE antenna is all wrong. Wire loops inside the electrostatic shield are perfectly OK to receive the RF and ARE the antenna. Electrostatic shield in small loop antennas reduces the interference, electrical noise locally generated (prevalent electrical fields).

Faraday shield is the cage, cube, tube of conductive material that is completely enclosed and prevents RF from penetration to the inside of the enclosure. Electrostatic shield has a slot, opening and prevents, attenuates electrical fields by virtue of its capacitance to the surroundings. Locally generated electrical noise, signals withing half wave or so are electrical fields in nature and are attenuated by the electrostatic shields, such as in properly designed small loop antennas.

I have built bunch of them, verified their performance and saw the effect. Interesting combination was using small loop in the proximity of Beverage, but that is another story.
 
73
Yuri Blanarovich, K3BU

----- Original Message -----
From: Donald Chester <k4kyv at hotmail.com>
Date: Sunday, May 14, 2006 5:39 pm
Subject: Re: Topband: QST Jun 06 RX Loop

> 
> >From: "Tom Rauch" <w8ji at contesting.com>
> 
> >...It is a very well known physical property of a "shield" more
> >than several skin depths thick that essentially nothing goes
> >through that shield. It's a Faraday cage, and when the
> >time-varying electric field goes to zero so does the
> >magnetic field.
> 
> 
> Tom:
> 
> One question that some readers of this forum might ask:  If that 
> is the 
> case, how does an inductively coupled network, where two resonant 
> inductors 
> are separated by a Faraday shield, transfer energy?
> 


 That is another example of the Electrostatic shield. Also used in AC and audio transformers.