"Telamon" wrote
"Jack Painter" wrote:

"starman" wrote

A low noise inverted-L will have the vertical downlead at the far end
of
the horizontal section with the balun located at the lower end of the
single wire downlead, near the ground. Then you can run coax back to
the
house from the balun. The near end of the horizontal section shouldn't
be too close to the house where it might pick up noise.

The 'low noise inverted-L' (paragraph above) can make a big difference
in lowering the noise that the antenna picks up from local sources.


There is not one ounce of truth to an "Inverted-L" being ANY quieter
than a
45 degree random wire, and especially a horizontal-dipole, which is
generally quieter than any antenna with a vertical component. Most
interference is vertically polarized, and the verticals, random-wires,
slopers, or inverted-L antenna designs all pick up more vertically
polarized
"noise" than a horizontally polarized antenna. Adding a vertical or even
a
45 degree sloped component to an antenna DOES make it less directional
than
a horizontal, and that is all it does. Any noise-limiting realized from
these designs comes strictly from the grounded-Balun and not the design,
configuration or dimensions of the antenna. Shield-grounding (for static
and
lightning protection) at the feedpoint will achieve 99% of the
noise-limiting benefit that a grounded Balun does. The missing 1% is an
equal loss of signal and noise through the Balun. All RF noise (but not
all
energy has RF components) is coupled right across the Balun windings,
their
function of electrically decoupling is true of some DC energy, but not
RF
energy, which is rather efficiently coupled across the Balun by design.

The same application of a grounded-Balun works equally well on both the
random (straight) wire antennas and inverted-L antenna btw. Both the
random
wire and inverted-L benefit from (require in most cases) a counterpoise
ground or radials to provide effective transmitting. Neither a
counterpoise
nor radials affect reception from the either the random wire or
inverted-L,
however.

I agree with all that you wrote except for that last sentence.

Every location is a different situation and so generalizations can be
made about antenna type, radials or ground performance but there are no
absolutes here. What is better in one place will not necessarily be
better in another. Likely yes, but not necessarily.

Some locations may be far better off with a counterpoise of some type
rather than depending on RF ground return through the radio and mains
supply, which is all that is left if that one ground rod the BALUN is
connected to is not up to the job.

As one example if you have good ground conductivity then that one rod
might be all you need but if ground conductivity is poor then a radial
or radials will make an improvement. You can always lay wires on the
ground and see if they help. If they do then you can go through the
trouble to make them perminent.

Any type of single element antenna (unbalanced) requires a good RF
ground to be effective. The RF ground is the other half of the antenna.


I agree with that. While only some "incomplete" (unbalanced wire) antennas
can radiate without a good RF ground, all antennas can receive with no RF
ground at all. But some receivers can benefit from better ground than the
AC-grounded case of the radio provides. Noise limiting is one reason we do
try to improve both the DC and RF ground capabilities of the coax-shield to
improve this possibility, agreed.

Jack Painter
Virginia Beach, Virginia