If you guys are bored with this topic and want me to simply shut up or move
the discussion off the reflector, let me know.
Laying in bed last night, I flipped the light on and grabbed the ON4UN book
and looked at beverage lengths reported by John and compared them to my new
spreadsheet calculations. From Table 7-2 on page 7-9 you will find the
following:
160 Meters (2 meters high over good ground--6.56 feet)
82-92 m (0.5 wavelength)
165-178 m
250-270 m (1.5 wavelengths)
332-352 m
410-430 m (2.5 wavelengths)
John reports a range of lengths. Frankly, you probably wouldn't be able to
"hear" any difference from different beverages within the lengths reported.
The spreadsheet is calibrated in feet so some conversion is needed:
160 Meters (Vp .90)
210 feet (64 meters)
566 feet (172 meters)
829 feet (253 meters)
1132 feet (345 meters)
1403 feet (428 meters)
So there you have it. With the exception of the so-called 0.5 wavelength,
which is really too short to be even considered a beverage, the spreadsheet
finds an "optimum" within range of all of the so-called "cone of silence"
lengths.
Before hastily running to the conclusion that the integration of the phase
differences along the length of line can be used to predict an "optimum
length" for other velocity factors, some sort of confirmation would be
prudent. Anybody know of other "optimums" reported over other types of
ground or at different heights? Anybody actually "tuned" their beverage for
optimum F/B or output that can report their measurements?
Also, since the spreadsheet performs the calculus by brute strength--by that
I mean measuring the area under the phase difference curve every
foot--actually doing the integral mathematically would be a preferred
method. Any Math professors out there that want to give it a shot--it is
well beyond my limited math (I have not actually done an integration problem
since college over 20 years ago).
If you guys are bored with this topic, just tell me to shut up and I'll
forget about it. If you are interested in more dialogue, some positive
feedback would be appreciated. Other areas of consideration include looking
at other bands (80 and 40) to see if there is any "magic lengths" that
should be considered. (de W4ZV Let's keep the focus on 160...thanks!)
Ford-N0OQW
ford@cmgate.com
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