[Antennas] " G5RV " TYPE ANTENNA / "CUSHCRAFT MA5V"ANTENNA QUESTIONS

[George, W5YR]

Danny, I don't know which George you are referring to, but in the event
that it is this one, let me just say that I think you gave a very good and
technically accurate picture of the situation. 

The basic theory of parallel conductor transmission lines says, of course,
that as long as the line spacing is "very small compared to a wavelength"
the EM fields from each conductor will tend to cancel one another and
thereby minimize radiation. 

By the same token, if the conductors are kept several wire-spacings away
from anything metallic, the net field around the line will be undisturbed
and the fields' ability to cancel one another will not be impacted.

That is really the problem with having metal too close to the line. The
presence of the metalaffects one conductor more than the other, that
unbalances the line in that area,  the fields no longer cancel, and
radiation can occur. Not to mention the effects on line impedance, etc. of
the capacitive coupling to the conductors, etc.

The usual rule of thumb is, as Danny reports, to keep the conductors at
least 2 or 3 line widths away from anything metallic. If you must come near
something metal, try to do it at right angles to the line for minimum
coupling effects.

Now, maybe the "real" George can weigh in!   <:}

73/72/oo, George W5YR - the Yellow Rose of Texas         
Fairview, TX 30 mi NE of Dallas in Collin county EM13qe   
Amateur Radio W5YR, in the 56th year and it just keeps getting better!
QRP-L 1373 NETXQRP 6 SOC 262 COG 8 FPQRP 404 TEN-X 11771 I-LINK 11735
Icom IC-756PRO #02121  Kachina 505 DSP  #91900556  Icom IC-765 #02437


K6MHE wrote:
> 
> Criss,
> 
> The 2� to 3 times has been around longer than I. However, if you can
> picture in you mind the magnetic lines of force surrounding a conductor
> where current is present and then place two conductors side by side spaced
> very close with current flow one way in one and the opposite way in the
> other you should be able to picture in your mind's eye lines of force an
> choking one another off. (One going is clockwise direction and the other
> counterclockwise) Nothing expands very far as they've beaten each other
> down to almost nothing. A little like Dr. Doolittle's pushme/pullme <grin>.
> 
> Not very scientific explanation, but how I've pictured it for years.
> 
> I'll stand by and hope George will jump in with a better (and more correct)
> answer.