[TowerTalk] "Q" (was no-subject)

[n4kg@juno.com]

On Wed, 20 Sep 2000  "Tom Rauch" <w8ji@contesting.com> writes:
> 
>	SNIP

> It's early yet and I'm still gathering numbers, but so far 
> it  appears  the largest ill effect of traps is they greatly 
> narrow the bandwidth  of  the elements on bands above 
> the lowest band (highest freq?) where the antenna is  used. 
> 
> It appears the ill effects are mostly that of causing the antenna to 
> be tuning critical in the parasitic elements, rather than actually 
> dissipating power. What it seems like so far, although it is too 
> early to say for sure, is that trap antennas probably mistune the 
> parasitic elements to get bandwidth...and that's where most of the 
> performance goes.
> 
> If that is the case, the solution would be to use a single trapped 
> driven element and perhaps separate full size elements for 
> reflectors and directors....or some combination of traps and full 
> size parasitic elements.
> 
> So far, actual dissipative losses appear to be very low.

	SNIP
> 
> 73, Tom W8JI
> w8ji@contesting.com
> 

Long ago, TELREX made a 2 element tribander, the TB4EM(?)
which used a TRAPPED  Driven Element and separate full size
reflectors for each band.  Looks like an interesting design to me
that could be easily homebrewed using a Mosley or CC  DE.

Note that the feed impedance of 2L Yagi's is higher than 3L
which translates to less detuning to get a decent 50 ohm match.

Wonder how that would compare with the C3S? 

de Tom  N4KG

 
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