[TowerTalk] quad

[Maurizio Panicara]

Sorry, but I've to insist on this point.
The sides of a 1Wl loops are NOT end loadings in any case, this is
conceptually wrong.
The current and voltage distribution along sides is varying like in a half
wave dipole or, eventually, like in a quarter wave transmission line.
Cut the 1 Wl loop at  voltage nodes and discard the dipole without feeding.
This is a bent half wave dipole with no end loading but with a linear
current and voltage distribution.
Now feed also the other half loop (the specular one), in phase.
This is another half wave dipole with a linear current and voltage
distribution.
Now, beeing the bent sides 180° out of phase the far field from them is
cancelled exactly like it happens with the loop.
A full wave loop is nothing else but the above, utilizing the side "joints"
also like a quarter wave transmission line to excite in phase the other half
(opposite) of the loop.

73,
Mauri I4JMY



----- Original Message -----
From: "Tom Rauch" <w8ji@contesting.com>
To: <towertalk@contesting.com>
Sent: Monday, August 14, 2000 1:43 PM
Subject: [TowerTalk] quad


>
> Hi Tom,
>
> Yes, I see how confusing it is to thing of a quad as two 1/4 wl end-
> loaded dipoles rather than two bent half waves, but there is an
> important distinction.
>
> A bent 1/2 wave dipole still has noticeable radiation in the far-field
> from the bent ends. A quad has close spaced equal and out-of-
> phase currents in the same area, and so those sections have
> virtually no far-field effect at all on the system. Other than coupling
> power to the other half, and end-loading, they might as well not
> even exist electrically.
>
>
> Any way we prefer to describe it, we are still left with two 1/4 wl
> long end-loaded radiating sections that are stacked 1/4 wl apart
> and fed in-phase. That's what is really important.
>
>
>
>
> 73, Tom W8JI
> w8ji@contesting.com



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