-=> 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 the
II> tassle type is really equal to the 2-wire type or if the resonance
II> of the of the longer leg disrupts the resonance of the higher
II> frequency portion.
JE> I'm not saying that it will "out perform" - everyone knows that a
JE> 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.
JE> While it's true you can use a 40m antenna for 15m, because 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?)
JE> Trapped dipoles are a compromise, also.
True.
JE> The idea behind the 'tassle', is to have one peice of wire 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.
II> Ah, the "joys" of moving... If I never have to move again it
II> will be too soon to suit me!
JE> ugh!
JE> I'm convinced that this is going to turn out to be a decent RF area,
JE> since I was heard with favorable reports in Dallas, Houston and other
JE> parts of Texas, this morning. This, on 75m, with a 40m antenna, and
JE> the pi-output of the Hallicrafter HT-37.
II> WOW! FB OM!
JE> I was expressed, too
II> My GUESS would be that the 2-wire type would outperform the
II> tassle type by some percentage... possibly a dB or so, possibly
II> several dB. Please let me know how your experiments turn out!
JE> It's not meant to be a replacement for the dipole... but I don't see
JE> 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> =================================|===============================
(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. 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?
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.
JE> Imagine (due to the lack of ascii drawing capabilities ) that the
JE> 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 something... so
JE> 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?
[snip]
II> That's how the Hams do it! ;-]
JE> Isn't that what "HAM_TECH" is about? ;-)
BINGO!
JE> Also trying to get Ruthie back in either here, and/or HAM (probably
JE> here - too many politics for her in HAM, and I can't blame her)
Tell her she has mail here, then send her some. ;-}
II> I can remember back in my Novice days, (about to 20 years ago),
II> sneaking up within KHz from the carrier of an International BC
II> station and calling
II> CQ... Made some nice contacts that way. The IBC carrier seemed
II> to boost me along. (That was CW, BTW!)
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.
JE> you operate CW, Ivy? I've been hanging around 7.040MHz (+/-)
II> No, right now the only band I'm on is 2M FM with a 5W brick and
II> a homebrew 6 dB co-linear J-pole. (See above).
JE> saw that.
II> I prefer voice and want to get into packet, including linking
II> my phone BBS to to a packet BBS.
JE> Not a 'do-able' thing, unless the message areas are TIGHLY controlled.
JE> There is a Packet Door, however, that will give 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!) :-}
II> I'm fortunate enough to have a window air conditioner to keep me
II> (and the computers) in the 70's. :->
JE> We've got one here - but it's in the living room - where the TV is
JE> We try to keep the whole house cool with it, and it's only 10k BTU.
I don't know what this old window unit is rated at, but about all it can
handle is this one room, (about 12' X 14'), and when it gets over 100
outside it's huffing and puffing. :-{
JE> When the west sun beats down on where the computers are, it gets kinda
JE> unbearable in here :-(
I can believe that! My two computers go on strike if the temp gets much
over 80 in here. Basically, this is a 2-room apartment: Kitchen and
everything-else-room. The AC, 2 computers, radio equipment, TVs and bed
are all in one room, so I have incentive to keep it cool. ;->
(Gotta keep this under 200 lines or my tosser gags on it).
73 DE KB9QPM
Ivy
... He said it was either him or the radio.
... Do it near resonance!
... Fido is a sick puppy! QUICK! Call the Vet at INTBBS_WK!
旼컴컴컴컴컴컴컴> Ivy Iverson, KB9QPM <컴컴컴컴컴컴�
읕> Ivy's WALL BBS - USA Co-Moderator, INTBBS_WK <켸
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