On 5/4/2010 8:17 PM, tom wrote:
On 5/4/2010 6:39 PM, Owen Duffy wrote:

Tom,

My use of "lossy" was to remind readers that capacitive reactance
obtained by using such a transmission line element is a relatively lossy
'capacitor'. For example. an o/c stub of RG213 for a reactance of -10
ohms at 144MHz has a resistance of about 0.1 ohms, or a Q of about 100.
That is not a huge loss, but quality capacitors achieve much higher Q
than that.

So, I don't know why one might use such a thing in a driven element,
introducing say 0.2 ohms of resistance which consumes about 0.4% of the
power if it was a R=50 feedpoint, when a similar reactance could be
obtained by a slight shortening. The purpose is probably not for
frequency compensation, it works the wrong way.

And I forgot to address this.

Because .4% is meaningless and the change to a slightly less lossy feed
method would contribute nothing useful for the effort.

Because the effort with your method is that I would have to trim an
element clip by clip instead of simply sliding things at the match.

tom
K0TAR