-=> On 07-10-97  12:06, Jeff Edmonson said to Ivy Iverson,<=-
-=>"About Multiband antennas...,"<=-
 
 JE> Hey, Ivy!
 
Hi again, Jeff;
 
 
 >  JE> Here's some antenna discussion fodder:
 
[snip]
 
 JE> |-----------------------| |------------------------|
 JE>        |                | |                 |
 JE>                         | |   <--Feedline
 JE>                         | |
 JE>                      ___|_|___
 JE>
 JE>
 JE> Above, the same 80m dipole with 40m 'tassles' installed.
 JE>
 JE> A 'tassle' is just a chunk of wire around 4 to 6" in length,
 JE> soldered onto the  existing dipole, at the distance from the
 JE> feedpoint calculated for 40m, to  allow for resonation at 40m.
 
 II> I haven't heard of using "tassles" for multibanding an antenna.
 II> The nearest I have seen is something that is commonly used:
 
 II>     |------------------------| |------------------------|
 II>            -----------------/| |\----------------
 II>                              | |
 II>                              | |
 II>                              | | <--Feedline
 II>                              | |
 
 > If you only need 2 elements, you can use standard 300 ohm
 > twinlead for such an antenna.  If you need more, you could use
 > 4-conductor rotor wire for a 4-element version.
 
 JE> See there?  The point is, WHY waste all that extra wire, when you're
 JE> only going to feed one wire at a time, anyway?
 
 JE> With the wave going to the resonant part of the antenna, it will
 JE> radiate from  there.
 
 II> Of course, there is nothing stopping you from experimenting with
 II> your tassle idea... hey, it might work great!  After all, isn't
 II> that what amateur radio is all about?
 
 JE> Bingo!
 
 JE> Actually, this idea DOES work - there are some people who have been
 JE> using this  antenna in town for around 10 years, now.  Just thought I'd
 JE> toss it out here,  to see what kind of reaction I could get.
 
Ten years, huh?  Ham radio has been around for over a century.  I find it
amazing that this has not been tried long before this!  It would be
interesting to do a side-by-side comparison - two identical antennas,
one of the two-wire design, the other using tassels, in the same location
and pointing the same direction: Raise one antenna, do field strength
measurements under known conditions, then lower that antenna and raise
the other one to the same position and repeat the measurments, then
compare the readings.  (Signal reports at a distance would be unreliable
due to changing band conditions during the time it takes to lower one
antenna and raise the other one).  IMO, this would be the only way to
do an accurate comparison.  I would be very intereted to see such a
comparison to see if the tassle type is really equal to the 2-wire
type or if the resonance of the of the longer leg disrupts the resonance
of the higher frequency portion.  Remember, the majority of the radiation
fro a transmitting antenna is at the highest-voltage point, in other
words, the unfed end(s).  If the ends of the higher-frequency section are
hanging vertically, I would think that would create lobes off the ends
of the antenna rather than broadside as in a standard dipole.  How strong
these side lobes are would depend on how long the tassels are.
 
My GUESS would be that the 2-wire type would outperform the tassle type by
some percentage... possibly a dB or so, possibly several dB.  Please let
me know how your experiments turn out!
 
[snip]
 
 JE> Well, right now I'm still working on getting one of my old
 JE> transmitters running again, so I CAN try some antenna experimentation.
 
Please do, and let us know what happens!
 
 JE> but, as I've said above, there's been some testing in this area, at
 JE> least, of  the idea - and it seems to be doing good.  I've not talked
 JE> to anyone who's  still using the antenna in so long, I don't even know
 JE> if they're still kicking. 
 
If it's successful and equal in performance to the multi-wire version,
it's a heck of a good idea which should spread like wildfire, (especially
among people like myself who are limited in both money and ability to
convince the landlord to allow yet another antenna on the property!) ;-}
 
Catch you later es 73 de KB9QPM
   Ivy
 
 
 
... Hams do it at resonance!
... When the band is open you can work the world on a piece of wet string!
... Antenna... Isn't that Uncle Harry's wife?
... Double your dipoles. Double your flux.
 
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           ÚÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ> Ivy Iverson, KB9QPM <ÄÄÄÄÄÄÄÄÄÄÄÄ¿
           ÀÄ> Ivy's WALL BBS - USA Co-Moderator, INTBBS_WK <ÄÙ
 
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