STARMAN,

At the Base Feed Point of the Inverted "L" Antenna two Radials
opposite each other set at 90 Degrees to the Horizontal Arm as
viewed from the Top. The Radials should be as long as the
Vertical Leg of the Inverted "L" Antenna.

* Inverted "L' Antenna Reading List
http://groups.yahoo.com/group/SWL-AM...na/message/374

* Inverted "L" Antenna for Transmitting by Dr. Ace
http://groups.yahoo.com/group/SWL-AM...na/message/309
Typically: Quarter (1/4) Wave Length Long and 1/8th WL High

* Inverted "L" Antenna as an 'available space' SWL Antenna
http://groups.yahoo.com/group/SWL-AM...nna/message/54
Typically: For a SWL Receive ONLY Antenna of any Random Length
With the Horizontal Arm 'twice' (2X) as long as the Vertical Leg.


iane ~ RHF
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= = = starman
= = = wrote in message ...

Mark Keith wrote:

starman wrote in message ...
Mark Keith wrote:

It's the improved decoupling of the feedline
from the antenna that reduces the noise level. "noise ingress" Not
the grounding itself, although the grounding helps in the decoupling
of the line.

I think we're talking semantics here, but how else could you decouple
the feedline of an inverted-L antenna other than using an effective
(short) earth ground connection?

As one mentioned, radials. Or you could use a choke,beads, etc. Lets
say you had a 1/4 wave ground plane that was elevated with a set of
radials. The radials will decouple the feedline pretty well. There is
no need to ground the radials, or the supporting mast, except as a
lightning concern. A choke will decouple the line fairly well. Noise
ingress has nothing to do with being grounded or not. It's an issue of
decoupling the feedline from the antenna. Using a ground connection
under an "L" will decouple it fairly well, but it's just one method
that can be used, and the "ground" is not a required element. It's not
just semantics, because an "rf ground" is not a requirement of good
decoupling. But saying that, I usually do ground the low end of inv
L's. MK

I agree that the feedline of an elevated ground plane can be effectively
decoupled using radials but it's not clear to me how you would use
radials with the typical inverted-L. Where would you locate the radials
in that case?