-=>> On 07-16-97 09:08, Jeff Edmonson said to Ivy Iverson,<=-
-=>>"About Multiband antennas...,"<=-
> Hi, Jeff;
> KA5THB DE KB9QPM BT
II>> I would be very intereted to see such a comparison to see if
II>> the tassle type is really equal to the 2-wire type or if the
II>> resonance of the of the longer leg disrupts the resonance of
II>> the higher frequency portion.
JE>> I'm not saying that it will "out perform" - everyone knows
JE>> that a mono-band antenna is the best for that band!
> Nobody expects it to outperform, (at least _I_ don't). What I
> was thinking was a comparison between a tassled multiband and a
> 2-wire dipole, (2 wires of different lengths on each side, IOW,
> parallel dipoles for 2 different bands and/or trap dipoles.
Today is the day. Don't have a field strength meter, per say - I've got a
scope, and a hunk of wire connected to it, so can measure the amplitude of
one antenna as compared to another. And, even at that, it's going to be a
trick to put up two antennas, string 'em up, and then measure that, take that
one down, and put up another antenna, which isn't going to be in the same
position. Readings will be comparable, at best - but not enough to base
facts on.
JE>> While it's true you can use a 40m antenna for 15m, because
JE>> of 21MHz
JE>> being the third harmonic of 7MHz, it's also true that if you cut an
JE>> antenna specifically FOR 15m, it will FAR outperform the 40m antenna!
> Taken for granted... Been there, done that, wore out the
> T-shirt. (Ever use a 2 M antenna on 440?)
Yup! Built several 'Copper Cactus' j-poles, that doubled as 440MHz antennas.
JE>> Trapped dipoles are a compromise, also.
> True.
JE>> The idea behind the 'tassle', is to have one peice of wire
JE>> with a
JE>> couple of RF stops along the way for (if desired) 20m, 40m and the
JE>> whole antenna for 75/80m.
> Yes, I am aware of this. I appreciate the thought, but please
> be aware that I earned an FCC Radiotelephone 1st class license,
> (# P1-16-7142), in July, 1964, and I got around to getting a
> Ham ticket a few years later. Among other things, I have been
> on the engineering staff of several radio & TV stations,
> including Chief Engineer of a small FM station, so I think I
> understand the basic principals of antennas a little bit. It
> was upon this history that I queried the effectiveness of a
> tassled antenna as compared to a "parallel dipole," or trap
> dipole. I would think that the longer wire would throw off the
> resonance of the "tassled frequency," however it may very well
> equal - or even surpass - the trap and/or parallel and trap
> types. This is what I was curious about. If I did not make
> myself clear before, my apologies. Please do not think that I
> am trying to be a smart-a** here, simply sharing with you a
> part of my history and qualifications.
Not a problem. Discussion is all were doing, and last I looked, your words
didn't leave me with any wounds };->
My dad was a chief engineer for a few broadcast stations in the San Antonio
area - he also used to be big into phased arrays. Had a 3 element phased
array on the roof-top, on 40m for a few years. Many's the night we heard
"This is the EAST Beam, and *>click<* this is the WEST beam - How copy?" ;-)
He had the front/back ratio on that thing up to as high as 40db. QUITE
effective for cancelling out the Broadcast stations on 40m that were
propagating from the East, when he was trying to talk Southwest (Austrailia)
II>> My GUESS would be that the 2-wire type would outperform the
II>> tassle type by some percentage... possibly a dB or so,
II>> possibly several dB. Please let me know how your experiments
II>> turn out!
JE>> It's not meant to be a replacement for the dipole... but I
JE>> don't see why it wont work as well...
JE>> (To All:)
JE>> Let's try to think in a less 'straight-line' mode...
> OK, I'll take your drawing farther... (rediculiously, so, just
> to make a point): 4-in-1 antenna: 160-75/80-/40/15 & 6 M...
JE>> /=\
JE>> // | \\
JE>> // | \\
JE>> // | \\
JE>> // | \\
JE>> // | | |\\
JE>> // D | D \\
JE>> / C | C \
JE>> /| | |\
JE>> / B | B \
JE>> A | A
JE>> |
JE>> |
JE>>
JE>> =================================|==========================
> (A) 160 M dipole with (B) 75/80 M tassles on 1 pair of wires,
> plus a second, parallel dipole, (same 2-conductor cable), cut
> for (C) 40/15 M, with tassles for (D) 6 M. 2 pairs of wires &
> 4 tassles forming (hopefully) 4 dipoles for 5 bands. I
> wouldn't expect to get WAS on it, but it might be servicable
> for several bands.
That's it, right there, in a nutshell. 4 dipoles for 5 bands -in the space
of ONE dipole!.
> The question is this: Would the tassle-type
> be equal to the 2-wire parallel type, (which has been used
> practically since the days of the rotary spark gap), or was it
> tried and discarded decades ago because the 2-wire type is more
> effective?
I don't know if anyone is still left, from the rotary spark gap days. Those
that are probably can't remember very well... One of the ravages of time,
that I'm feeling now, and I'm a young pup of 38!
> We might as well use single-band dipoles for each
> band as the standard to compare the other types to, if you, (or
> someone else), felt ambitious enough to do all this. Of
> course, I used 160 M as the basic length only for illustration.
> The longest dipole could be cut for almost any band.
Without having the real-estate, it makes a difference.
Probably the best way to hang the antenna, would be as flat as possible for
the lowest band, then angle down the 'tassle' for the higher freqs.
JE>> Imagine (due to the lack of ascii drawing capabilities )
JE>> that the ends are tied off to their respective points.
> Understood.
JE>> at the 40m points, solder a peice of wire to the existing antenna
JE>> (after the resonant point is found) and then pull then end of the
JE>> TASSLE out, with a peice of rope, or insulate it, or
JE>> something... so that it's -kinda- in the same plane as the dipole.
> Ok, but my question boils down to this: Would the tassels be as
> effective as using 2 (or more) conductor wire, cutting each
> conductor pair for different bands? And how would either
> compare with a trap dipole for the same bands under the same
> conditions?
What's the difference? There'll be enough capacity between the two
conductors, even if they're insulated so that it 'appears' to RF as a single
conductor, until one of those conductors is cut.
With that thought, hanging the 'tassle' eliminates the need for another
conductor a whole 33' (using 40m as the second band on a 75/80m dipole) out
from the feed point.
JE>> *enhhhh* you're kinda infringing on the border of intentional
JE>> interference - but that was years ago now, and the BC station didn't
JE>> complain, so not much to do about it, now
> I don't feel that way... with his half a gazillion watts and my
> 25...??? I wasn't even running the 75 W legal limit for novices
> back then.
The BC station may have had a gazillion watts at the source, but the recieved
site is easily interfered with, if the interferring station is *MUCH* closer
than the originater };->
II>> I prefer voice and want to get into packet, including
II>> linking my phone BBS to to a packet BBS.
JE>> Not a 'do-able' thing, unless the message areas are TIGHLY
JE>> controlled. There is a Packet Door, however, that will give
JE>> pre-approved hams
JE>> packet access, via the BBS. The door program takes care of everything
JE>> security-wise.
> Yep! Got a couple of them on CD-ROM. They require
> preauthorization by the SysOp... not sure if others can read
> the mail or not. (I think they can with one). When a packet
> is sent it uses the other Ham's call, (as they were
> pre-registered), not the BBS's call. (It's Cover Your A__
> time!) :-}
(*(ROFL)*)
Think I've still got a copy of TNCDR106.ZIP around here, somewhere.
> ... He said it was either him or the radio.
That answers THAT question };->
=========================================
73 = Best Regards ka5thb@bigfoot.com
-Jeff KA5THB
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* Origin: A point of The Electronic Avenue (1:387/510.1)
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