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. It has 0 dB when referenced 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.
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.
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.
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.....
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. 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. 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.
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.
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?
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).
A tuner requires readjustment when changing channels within the CB,
and most CBers don't want to deal with the hassle. 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. 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.
Then there is the issue of the non-resonant 5/8-wave antenna..... oh,
Dave, when will you learn?
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.
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. I answered your question, now you answer mine: what's
the name of your tech school, Dave?
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.
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. 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. 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. 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.
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.
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