[TowerTalk] Helical resonators, Q, and measurements

[Tom Rauch]

Hey GW, sorry I deleted your post and can't recopy.

I'd like to point something else out. Narrow bandwidth does not 
necessarily indicate low loss. While we often think that is true, 
more often than not the two are unrelated parameters.

I can give a specific example. A loaded antenna with substantial 
capacitance shunting the loading inductor compared to one with 
minimal capacitance shunting the inductor. The reactance change 
with a given frequency change of the inductor / shunt capacitor 
combo is much higher than the reactance change of a pure 
inductance EVEN if loss is higher in the narrow-band loading 
system!

The most efficient mobile antennas I have for either 160 and 40 
meters are also the broadest bandwidth mobile antennas I have!
 
The real world screws up textbook measurements all the time, 
that's why critical measurements should ALWAYS be measured 
with multiple validation using the most direct methods possible. If 
you want to know field strength in the main lobe compared to field 
strength in another main lobe, measure it there at least two totally 
different ways. Don't throw needless extra variables into the 
equation.

Measure what you want to know, not something else far down the 
food chain.



73, Tom W8JI
w8ji@contesting.com

--
FAQ on WWW:               http://www.contesting.com/towertalkfaq.html
Submissions:              towertalk@contesting.com
Administrative requests:  towertalk-REQUEST@contesting.com
Problems:                 owner-towertalk@contesting.com
Search:                   http://www.contesting.com/km9p/search.htm