"Quarter wave ground mounted radials are a waste of wire."
 

On Oct 2, 10:33 am, Jim Kelley wrote:
Cecil Moore wrote:
Jim Kelley wrote:

Cecil Moore wrote:

A foot of wire with reflections at one GHz has
the same current throughout the circuit?

A simple series circuit can be expected to behave as a simple series
circuit. Other circuits can be expected to behave differently. Which
do you think applies?

An *ordinary prudent man* would think that one foot
of wire is a "simple series circuit" and it is in a
DC circuit.

Most ordinary prudent men that I know wouldn't characterize a one foot
length of wire as a series circuit.

ac6xg

The fact that it's described as having a physical dimension suggests
that the physical extent matters. I don't know what an "ordinary
prudent man" is, but I suppose most people I stopped on the street
wouldn't have a clue what I was talking about and their eyes would
kind of glaze over with the mention of "wire" and "circuit."

Cheers,
Tom

(presently playing with circuits below 100MHz where 1mm can make a
huge difference in performance...who finds folk who say we don't
understand such things as distributed circuits deeply offensive,
especially when they make it abundantly clear they don't understand
such circuits themselves...)

"Quarter wave ground mounted radials are a waste of wire."
 

Jim Kelley wrote:

Cecil Moore wrote:
An *ordinary prudent man* would think that one foot
of wire is a "simple series circuit" and it is in a
DC circuit.

Most ordinary prudent men that I know wouldn't characterize a one foot
length of wire as a series circuit.

More silly word games - when it is in a DC circuit
the current is constant. When it exists in a simple
series GHz circuit with reflections, the current
is not constant.
--
73, Cecil http://www.w5dxp.com

"Quarter wave ground mounted radials are a waste of wire."
 

"Cecil Moore" wrote in message
...
Jim Kelley wrote:

Cecil Moore wrote:
An *ordinary prudent man* would think that one foot
of wire is a "simple series circuit" and it is in a
DC circuit.

Most ordinary prudent men that I know wouldn't characterize a one foot
length of wire as a series circuit.

More silly word games - when it is in a DC circuit
the current is constant. When it exists in a simple
series GHz circuit with reflections, the current
is not constant.
--
73, Cecil http://www.w5dxp.com

you don't even need reflections. a properly terminated piece of wire has a
different current at every point along the wire.

"Quarter wave ground mounted radials are a waste of wire."
 

Dave wrote:
"Cecil Moore" wrote in message
...

Jim Kelley wrote:

Cecil Moore wrote:

An *ordinary prudent man* would think that one foot
of wire is a "simple series circuit" and it is in a
DC circuit.

Most ordinary prudent men that I know wouldn't characterize a one foot
length of wire as a series circuit.

More silly word games - when it is in a DC circuit
the current is constant. When it exists in a simple
series GHz circuit with reflections, the current
is not constant.
--
73, Cecil http://www.w5dxp.com


you don't even need reflections. a properly terminated piece of wire has a
different current at every point along the wire.

At any given instant. :-)

ac6xg

"Quarter wave ground mounted radials are a waste of wire."
 

Dave wrote:
you don't even need reflections. a properly terminated piece of wire has a
different current at every point along the wire.

That's true but the attenuation factor in one foot
of wire might be hard to measure. Introduce reflections
and even a lossless wire will vary the current from
max to min every few inches at GHz frequencies.
--
73, Cecil http://www.w5dxp.com

"Quarter wave ground mounted radials are a waste of wire."
 

"Cecil Moore" wrote in message
...
Dave wrote:
you don't even need reflections. a properly terminated piece of wire has
a different current at every point along the wire.

That's true but the attenuation factor in one foot
of wire might be hard to measure. Introduce reflections
and even a lossless wire will vary the current from
max to min every few inches at GHz frequencies.
--
73, Cecil http://www.w5dxp.com

you don't need any loss either. a properly matched lossless line will have
different current at each point along the line.

"Quarter wave ground mounted radials are a waste of wire."
 

Dave wrote:
you don't need any loss either. a properly matched lossless line will have
different current at each point along the line.

Different RMS current?
--
73, Cecil http://www.w5dxp.com

"Quarter wave ground mounted radials are a waste of wire."
 

"Jim Kelley" wrote in message
...


Dave wrote:
"Cecil Moore" wrote in message
...

Jim Kelley wrote:

Cecil Moore wrote:

An *ordinary prudent man* would think that one foot
of wire is a "simple series circuit" and it is in a
DC circuit.

Most ordinary prudent men that I know wouldn't characterize a one foot
length of wire as a series circuit.

More silly word games - when it is in a DC circuit
the current is constant. When it exists in a simple
series GHz circuit with reflections, the current
is not constant.
--
73, Cecil http://www.w5dxp.com


you don't even need reflections. a properly terminated piece of wire has
a different current at every point along the wire.

At any given instant. :-)

ac6xg

TADA! And Jim gets the cigar!

Cecil, you take too narrow a view. at any given instant in time if you
measure the current along a properly matched wire you will measure a
different current and voltage all along the wire (repeating every wavelength
minus losses of course). nothing was stated that required rms, other
average, peak, or phasor representation.

"Quarter wave ground mounted radials are a waste of wire."
 

Dave wrote:
nothing was stated that required rms, other
average, peak, or phasor representation.

Nothing was stated that required the signal
source to be turned on either.
--
73, Cecil http://www.w5dxp.com

"Quarter wave ground mounted radials are a waste of wire."
 

Dave wrote:
"You don`t even need reflections. A properly terminated piece of wire
has a different current at every point along the wire."

Instantaneous values, of course. But, proper termination means no
reflection. The only source of variation along a line other than
attenuation is reflection. In a uniform line, attenuation causes a
steady decline of energy as energy travels. With a lossless line,
properly terminated, variation of rnergy along a line is only the phase
produced instantaneois values along the line. These are resolved during
the period of a cycle by the root mean square calculation.

Best regards, Richard Harrison, KB5WZI