On Tue, 12 Apr 2005 08:02:09 -0400, Dave Hall
wrote in :
On Fri, 08 Apr 2005 18:27:15 -0700, Frank Gilliland
wrote:
On Fri, 08 Apr 2005 13:59:47 -0400, Dave Hall
wrote in :
snip
Maybe you had difficulty, but there are a very large number of hams
-and- CBers who don't share your ineptitude.
A dipole is a dipole. It has 0 db of gain,
Wrong. A 1/2-wave Hertzian dipole has a gain of roughly +3 dBi in free
space.
Isotropic is a theoretical spherical reference model which does not
exist in reality. A dipole is THE reference antenna, by which most
credible gain claims are based against.
Antennas are referenced to either or both because both are constants.
It has 0 dB when referenced to itself.
Isn't that what I just said?
Unfortunately, yes, that's exactly what you said, and it's absolutely
dumb since -every- antenna has 0 dB gain in reference to itself.
and that assumes a resonant
dipole .
That's an assumtion -you- made, and it's also wrong: A resonant dipole
can be any multiple of 1/2-wave, and has a gain that differs depending
upon the length and directionality.
Then it's no longer a half wave dipole. You are now talking double
ended zepp designs, which do exhibit gain over a 1/2 wave dipole
But you didn't say "half wave dipole". You said only "dipole" which
could be any kind of dipole, be it a double-ended Zepp or the rabbit
ears perched on top of your overused television set.
If the dipole is non-resonant and requires a tuner to force
an impedance match, it will have further losses.
Wrong again. A tuner only adds insertion loss, which is usually quite
small if it's built with quality components. The insertion loss is
easily overcome by slightly increasing the length of the elements,
which is no big deal since the antenna is already non-resonant.
You fail to consider the standing waves which will still be present in
the feedline due to the mismatch. A tuner only presents a proper match
to the transmitter. With a high mismatch in the feedline, losses
increase as well and creating a tendency to radiate from the feedline.
In order to compensate for this the tuner should be mounted at the
feedpoint of the 4:1 balun that is normally used to feed 450 Ohm
ladder line to such designs. But such is impractical for guys who
change bands and frequency often, unless the tuner is automatic.
-YOU- failed to notice that I made no mention of a transmission line,
although I -did- reference a page from a ham that used ladder line. A
lot of inexpensive tuners include a 4:1 balun for a balanced output,
and SWR losses on ladder line are negligible. The only SWR you need to
worry about is between the radio and tuner.
But keeping with the original perspective, of a simple antenna system
for Vinnie, this falls far short of that objective.
Simplicity dictates buying an Imax or Antron and sticking it in a tree
or on a pole. Plug-n-play. You can't get much simpler than that. The
complexity arose when you threw a fit after my suggestion that Vinnie
might want to try and make his own antenna.
It won't stand a
chance against a commercially produced (or home made if you are
so-inclined) 5/8th wave vertical (with proper radials, not an Imax).
Well guess what, Dave -- a 5/8-wave antenna is a non-resonant antenna
and requires some method of impedance matching. Thank you.
A 5/8 wave is most certainly resonant. It's just that the feedpoint
impedance is high and needs to be transformed. It's a different issue
than forcing a match from something that is not resonant naturally.
You never fail to amaze me with your repeated offerings of technical
ignorance. Time for your next lesson:
A tuner is a device that is used to transform impedances. It has two
ends: an input and an output. Therefore, it connects to two devices: a
source (transmitter in Tx) and a load (antenna in Tx). The input of
the tuner is adjusted to match the output impedance of the source, and
the output of the tuner is adjusted to match the input impedance of
the load. And I hope it's safe to assume that you already know that
much.
But what you fail to realize is that impedance can be resistive,
reactive, or both. And since a tuner isn't limited to transformation
of resistances only, you can use a tuner to compensate for the
reactive component of the load (e.g, a feedline with SWR or a
non-resonant antenna).
Now what happens when you use a tuner to cancel the reactive component
of a load? Think hard, Dave..... reactive components cancel..... can
you figure it out by yourself? No, I didn't think so. The tuner and
the load become RESONANT. So you use a tuner to make a resonant
antenna -system- using a non-resonant antenna! And that's exactly what
is happening when the input impedance of a 5/8-wave antenna is
"transformed" so it can be driven from a resistive source -- a
non-resonant antenna is brought to resonance with a tuner.
Geez Dave, you sure are a dumbass.
You can have a 1:1 SWR but not be 50 Ohms.
Where did I suggest anything of the sort?
Time to read some more books. Or better yet, befriend an experienced
ham to show you.
Speak for yourself, dummy.
I've done this type of
antenna myself and never had any problems with local contacts -- in
fact, it worked a lot better than the 9' whip on the truck.
I find that very hard to believe, assuming identical height and
conditions, as my own experiences prove otherwise.
Oh, the humanity.....
This coming from someone who looks at people who share healthy
relationships as being "co-dependant", and prefers instead the
isolation of "independence".
I ran a home brewed wire dipole on CB years ago, and used it in
addition to my main 5/8th wave antenna. While the dipole worked well
when the skip was running, locally, the signal from the dipole was a
few "S" units less than the ground plane. With 4 watts of power, you
don't get much range on a horizontal wire dipole strung in a tree.
Well there's your problem, Dave -- I didn't say anything about
horizontal. On the contrary, it's better if it isn't.
Yea, if you're talking local. For DX, horizontal is usually better for
a number of reasons, most notably a lower noise floor and better take
off angle.
A horizontal dipole can have a wide variation in take-off angle
depending on height above ground, ground resistance, proximity to
other structures or objects, etc.
Yea, so?
And the noise floor may be slightly
lower but that's a product of it's directivity, as compared to a
vertical which is omnidirectional.
No, it's a product of the fact that most atmospheric and man-made
noise tends to be vertically polarized.
Wrong. Noise "tends" to have the polarity of the sources. The sources
of noise can be mostly vertical -or- horizontal depending on a number
of factors, not the least of which are geographic location, time of
day (as well as season), solar activity, band of operation......
A pair of phased verticals, as well
as any other directional antenna or antenna array, will also have the
effect of lowering the noise floor.
Not if the noise isn't concentrated in a single direction.
.......and direction of the antenna.
Like I said
before, just throw some wire up into the trees (or whatever tall
object happens to be available). Didn't you read the link I posted?
Of course. But a dipole is a basic antenna. It has no gain.
Wrong again. As I said before, a 1/2-wave Hertzian dipole in free
space has about 3 dB gain over an isotropic antenna; but a dipole is
merely an antenna with two elements and is not limited to a 1/2-wave
Hertzian configuration. Not only that, but a tuner isn't limited to
dipole antennas -- they can load up a long-wire just as easily.
Ah, so you're changing the parameters of the discussion. Long wires
are inefficient on CB as well. Been there, done that.
I changed nothing. You probably had a problem with the long-wire
antenna because you were expecting an omnidirectional pattern, which a
long-wire does not have. It -does- have very sharp lobes with high
gain, and if you know where to point them then a long-wire antenna
works just dandy; as you say, "been there, done that".
A properly
made purpose built CB antenna will out perform it.
Get a clue, Dave. You're an Extra, right? What's the name of that tech
school you claim to have attended?
What's your call sign Frank?
I understand that you have a problem with reading comprehension, but
what part of "I am not a ham" did you not understand? You are starting
to sound like Twisty -- are you going to start accusing me of being
five different hams?
Frank, all the king's horses and all the books you read will not make
up for your glaring lack of experience. Get out from behind the table
and DO something, and then report back.
Are you suggesting that after being a CBer since I was a kid, serving
several years in the USMC working on radios from LF to microwaves,
several more years in a commercial radio shop, several -more- years as
a BE, being self-employed as a both a tech and an engineer for most of
my life, and currently experimenting with weak-signal reception on the
1750m band and below 9khz, that I don't have any experience in radio?
Dave, you're an idiot.
Let's look at this from a practical standpoint. If a non-resonant,
tuner fed dipole worked so well, then why aren't all CB'ers using one?
Why would people want huge 5/8th wave antennas then? Better tell Jay
to forget about selling his Interceptor, since a simple non-resonant
dipole will work just as well and for far less money.
This resounds back to your argument that roger-beeps were illegal
because most radios didn't include them. The problem is that a tuner
requires a little skill and practice to use, which is beyond the scope
of the intended purpose of the service (a plug-n-play radio service).
Antenna tuners were available as an accessory for CB for less than the
cost of a good SWR meter. Granted they were simple coaxial in and out
tuners.
A tuner requires readjustment when changing channels within the CB,
and most CBers don't want to deal with the hassle.
So you are now claiming that CB'ers are too "dumb" to handle that?
Where did I suggest anything of the sort?
And to add further evidence to your lack of experience with CB, it was
common that "matchboxes" were often used by CB'ers to "correct" a
mismatch within their antennas. Instead of taking the time to properly
tune the antenna, they forced the match with the tuner. The radio was
happy, as it saw a 1:1 SWR, but the signal was not so good. When a
more knowledgable person would finally retune the antenna, and the
tuner was removed, signal improved considerably.
Wrong. Those little matchboxes (I still have a couple Johnsons) were
popularized during a time when a 1:1 SWR was widely considered to be
the holy grail of antenna tuning, that you needed to squeeze every
milliwatt from the radio. That attitude changed, and fewer CB tuners
were built, as more and more CBers learned that a few points on the
meter make very little difference.
Regardless, there
are still many CBers that do indeed use a tuner, not just with prefab
antennas but also with homebrew and beverage-can hooks.
None of which are work a tinker's dam for local CB communications.
You say that as if you have evaluated every antenna ever built. Yet
you haven't been here to evaluate -my- antennas..... have you been
playing with your crystal ball again, Dave?
And just about
every CBer who runs a tube linear uses a tuner because it's built into
the amp, which by itself blows big holes in your "practical" argument.
Not at all. A tube amplifier requires a tuner because the impedance of
a tube is much higher than 50 ohms, and needs to be transformed. It's
not practicality, it's necessity.
It's not "necessity" since the amp is not a necessity -- there is
always the alternative of using a solid-state amp, or no amp at all.
Then there is the issue of the non-resonant 5/8-wave antenna..... oh,
Dave, when will you learn?
The question is Frank, when will you start?
What's the name of your tech school, Dave?
A non-resonant dipole has ONE big advantage. It's a compromise antenna
that will work on all the HF bands. That's great if you don't have the
room to put up single band antennas for each band. But like any
compromise, it will not work as well as a dedicated antenna for each
band. Such a compromise is usually acceptable for a ham who has 1500
watts on tap. But for a 4 watt CB'er, who needs to squeeze every watt
of ERP he can for best local range, he needs a high gain efficient
antenna.
If that were the case then every CBer would have a 5-el yagi on a 30'
mast and a 9' whip on their vehicles.
Most high performance CB'ers do.
So most high performance CBers spend their time and money on equipment
designed to maximize their 4 watts?
For ham band use, I agree with you, just not for CB.
What's the name of that tech school, Dave?
What's your call sign Frank?
I'm not a ham.
Yet you are trying to impart your opinion on a subject you have not
participated in?
Antennas are reciprocal. What's the name of your tech school, Dave?
I answered your question, now you answer mine: what's
the name of your tech school, Dave?
The fact that you keep asking, makes me all the less likely to tell
you.
Yet another cop-out. You probably sent in for one of those mail-order
schools and never finished it.
Frank, your experience with both ham and CB radio is sorely lacking.
You read a few books and web sites and think you have all the answers.
OTOH, I've walked the walk for the last 30+ years and have played with
more antennas and equipment than I can remember. I have also been in
contact with people in the know when it comes to antennas. What I
know, I know through experience, and that's worth 10X what you read in
any book.
Which explains why your theory is severely lacking. If you took the
time to actually learn why these things work and -then- applied them
to your experiences, you could be the guru you think you already are.
But you don't and you're not. Instead you do things backwards: you
theorize about radio based on your own experience, then read only
enough to validate your own conclusions whether they are right or not.
If the evidence supports the theory, then it's valid. If not, then the
theory is wrong.
Then where are the facts to support your theories, Dave?
......gee, that sounds familiar..... I seem to recall challenging you
to produce facts in previous discussions, but you never came up with
any. Why should this time be any different?
You are a perfect example of someone who is
book-smart and street foolish. You will sit there and tell people, who
do these things every day, exactly why they can't possibly work.
Where have I -ever- said anything of the sort?
While
we sit here and laugh at you, because we've been there and done that.
Who is "we"? You and your imaginary groupies?
Check this out, Dave: Education doesn't come from a textbook that some
geek sat down and wrote just for ****s and giggles. It's a compendium
of knowledge that has been collected from over a century of research,
experimentation and practical experience by experts in all aspects of
the field. Those experts didn't become experts simply by playing with
CB radios as a hobby for 30 years. And an education doesn't include a
couple textbooks, a few lectures and a test -- it also includes years
of experience with the practical application of that knowledge.
No kidding. You seemed to have failed the "practical application"
aspect. Hell, you never even heard of the term "drying out" in
reference to electrolytic capacitor aging,
Where did I say that I had never heard the term before? I didn't. What
I -did- say was that it was an inappropriate term. And not to forget
that the subject came up because you deviated from the topic of how
you used your crystal ball to divine the cause of a CB malfunction.
and you try to cover this
glaring hole by claiming a pompous, superior attitude as if this was
beneath you.
No, -you- are beneath me, Dave, and that's where you'll stay until you
pull your head out of your ass.
When
you mock those that have a formal education and extensive experience
in electronic communication then you mock the same people who made the
television set you watch way too much, the telephone and cell-phone
infrastructure that keeps this world talking, the NASA and JPL
engineers who communicate with space probes billions of miles away,
etc, etc, etc.
I'm not mocking them.
Of course you are. You mock the very idea that anyone with an
education could know more about radio than what you have learned from
playing with toys for 30 years. You think that just because you
learned something on your own that nobody else has the right to
profess such knowledge, and just because they didn't 'earn' it like
you did. Yet instead of improving yourself by learning something new
you focus on the biggest difference between us -- an education -- and
try to hold it against me as some kind of professional malfeasance.
Well, that has to be one of the most ridiculous arguments that was
ever conceived: "You is dumber'n me cuz you gots a ed-u-kashun."
They know what they are doing. And I work with
many of them on a daily basis. You probably have products in your home
(or will) that I have had a part to play in their development.
You delivered the pizza for the engineers when they were burning the
midnight oil. BFD.
I
work in the field every day.
What "field" is that, Dave? The field of dreams?
I am not mocking them, I am mocking you.
You who CLAIM to be educated, but evidence suggests you are sorely
lacking in practical application of whatever it is you might have
learned.
Shall I make a list of what I have taught you about radio and
electronics since the last list? How long ago was that.... just a
couple months ago, wasn't it?
While I may not have participated in any world-changing
technology, I certainly have an education and the experience in the
field that puts you to shame.
While you tend bar and drive a 20+ year old truck......
Now your memory is failing, Dave -- did you forget so soon that I'm
currently designing and building a studio? It's going to take an extra
week because of the late-season snow in the pass (can't get any decent
acoustic panels in Spokane), but I didn't lose any money because of
the delay -- I still get $5k for the job when it's done, which is a
lot more than you get delivering pizzas in your lime-green Gremlin.
Yet -you- try to teach -me- theory based
on your education from a third-rate vocational tech school, a few
years in a CB shop, and your experience in =amateur= radio.
As far as you know.
Don't even -hint- that you have any kind of technical or engineering
job in the radio/electronics field because I'm not buying it for one
second. You have proven your ignorance on the subject so many times
that it's well beyond the realm of probability.
But it is evidently light years ahead of those
internet websites you lift your information from while you sit at home
alone with no other people to "relate" to.
And here's the kicker: Do you have any idea where I came up with the
idea to just throw a couple wires in the air and load them up with a
tuner? A ham.
Not all hams are mensa candidates.
Finally..... you have provided proof for one of your claims! Ok, so
you provided the proof -before- you made the claim, but at least it's
a start.
And most hams know that one antenna
solution, which may be great in one application, is not necessarily
good in another. In ham radio, there is no "one size fits all" answer.
Who said there was?
But then again, you wouldn't know that. You're not a ham (or CB'er).
Dave, go back to rec.boats and learn how to float -- your boat sank
here a long time ago.
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