On Thu, 04 Mar 2004 18:18:46 GMT, "aunwin"
wrote:

Why must only series circuits be considered for radiators?.

Hi Art,

I don't know if there's a "must" to this. Every series circuit can be
seen as a parallel circuit; and on the flip side, every parallel
circuit can be seen as a series circuit. It is all a matter of where
you put your leads to drive/measure/load/receive.... The same
components vary only slightly in frequency from their being series
resonant or parallel resonate. Without that
drive/measure/load/receive path, there is no energy transfer and power
consumption is all strictly a matter of component ohmic loss.

What is it about parallel circuits that make them unsuitable?

They are used every day to load up halfwave verticals, which in turn
are also parallel equivalent circuits. The input to the parallel
interface is performed through divider action (usually a tapped coil,
but could be through a capacitor divider).

Is stagger tuning a parallel circuit ?

No, but it could be. Stagger tuning, by convention is a chain of
separately tuned circuits, be they RC, RL, or LC (or, of course RLC).
One RC or RL circuit exhibits a 6dB/Octave or 10dB/Decade roll-off.
One LC circuit exhibits twice that or a 12dB/Octave or 20dB/Decade
roll-off. Again, it is all a matter of connections for the identical
components (which will show a slight shift in parallel to series
resonance frequency - which is to say it is application dependent).

Two RC or two RL, or one RC with one RL in cascade constitute "stagger
tuning" irrespective of what frequencies their roll-off occur at (this
sets the stage for Bandwidth) and their sum contribution equal roughly
one LC circuit (which does not qualify as "stagger tuned") as long as
they share the same characteristic frequency (where the roll-off
occurs which is generally defined at the 3dB inflection).

Now, as to the expression "roll-off" used liberally above. All such
circuits may be called "de-emphasis" (where roll-off is evident) or
"pre-emphasis" (where roll-up would be more descriptive). The
application is strictly a matter of where the drive is applied, and
where the load takes its output.

73's
Richard Clark, KB7QHC