On Nov 21, 5:53*pm, Rich Grise wrote:
On Thu, 20 Nov 2008 16:58:46 -0800, Roy Lewallen wrote:
Rich Grise wrote:
On Thu, 20 Nov 2008 15:30:26 -0800, Roy Lewallen wrote:
GregS wrote:
Ever hear of the BOW TIE. Its a sort of Fractal antenna. Having a wide
band. It could be improved by making it a full fractal.
That's interesting. In what way(s) is it improved by making it fractal?
How much is the improvement? Can you point me to a reference about this
which gives some quantitative data?

http://www.google.com/search?hl=en&q...s%22&btnG=Goog...

Sorry, it doesn't. Among the claims, trolls for investors, and
testimonials, where is the quantitative data showing that a fractal
antenna is in any way better than a bow tie, in what ways, and how much?
In other words, exactly where is the evidence on which you based your
statement?

The only "evidence" I have is a "testimonial" by the guy who invented it,
on some PBS show. And they claimed that that's how they pack so much
antenna into a box the size of your thumb. ;-)

And, having a passing familiarity with fractals, it just sounds eminently
plausible to me. :-)

Cheers!
Rich

Their advertising budget suggest that they are getting sales and they
do radiate
to the satisfaction of their users They don't have lumped loads so
where ';s the beef?
Art

On Fri, 21 Nov 2008 06:36:32 -0600, Cecil Moore wrote:
Sal M. Onella wrote:
If even poor antennas work well, why all the whining?

I've not had any problems with the UHF circular loop that comes with
standard rabbit ears. The only problem I've had is with VHF channels on
the dipole. I need a weatherproof version of my RS rabbit ears.
Unfortunately, ABC is Channel 7 here in Tyler, TX.

Where I'm sitting here in Whittier, KABC 7 is so strong I can get it
without even a cable plugged in!

It's 50, 56, and 58 I worry about; 2-13 and 28 are covered; I'm looking
forward to seeing if my new bowtie (from that youtube video, but with
ER708-2 x 1/16 filler rod) will pick up PAX on 30. They have some nice
oldies sometimes. (I also have some of the ER708-2 in 0.045".)

I'm gonna solder it together and hold it to the board with brass thumb-
tacks. ;-)

Just for reference: http://www.youtube.com/watch?v=EWQhlmJTMzw

Cheers!
Rich

christofire wrote:

All else being equal, a lossless 'ground plane' type antenna, be it a
monopole developed from a dipole or a discone developed from a biconical
dipole, over an infinite ground plane should exhibit 3 dB _more_ gain than
the symmetrical 'parent' form of antenna. This is because its radiation
pattern is limited to half the solid angle of the parent (e.g. only the
space above the ground plane). Then for a given number of watts fed into
the antenna, the power-flux density must be greater in the region where it
can radiate. In practice, the ground plane isn't infinite so there is some
'undercutting' of the vertical radiation pattern, but the gain should still
be somewhat greater.
. . .

This is entirely a fictional scenario, although it's the one used by
virtually all the currently available modeling programs. In those
programs you can choose "free space" or "ground plane", where the
infinite "ground plane" restricts the field, as Chris says, to a single
hemisphere while "free space" allows radiation in both hemispheres.

In real life, you can't have either one, except that outer space would
be a reasonable approximation of "free space". The only thing that
matters is whether the field reflects from a large surface like the
Earth on its way to the receiver. If it does, you potentially pick up
field strength from reinforcement of the direct and reflected rays --
but of course you can also lose field strength if the two rays cancel
rather than reinforcing. This is another way of describing the same
phenomenon of increased gain due to a ground plane. Even if you put an
antenna hundreds of wavelengths high, some of the signal will reflect
from the ground -- it's not truly in "free space". It doesn't matter
whether your antenna is a "ground plane" or a dipole -- if a reflection
occurs between the transmitter and receiver, you potentially get that
extra gain; if it doesn't, you don't.

Roy Lewallen, W7EL

On Nov 21, 7:04�pm, Art Unwin wrote:
On Nov 21, 5:53�pm, Rich Grise wrote:





On Thu, 20 Nov 2008 16:58:46 -0800, Roy Lewallen wrote:
Rich Grise wrote:
On Thu, 20 Nov 2008 15:30:26 -0800, Roy Lewallen wrote:
GregS wrote:
Ever hear of the BOW TIE. Its a sort of Fractal antenna. Having a wide
band. It could be improved by making it a full fractal.
That's interesting. In what way(s) is it improved by making it fractal?
How much is the improvement? Can you point me to a reference about this
which gives some quantitative data?

http://www.google.com/search?hl=en&q...s%22&btnG=Goog...

Sorry, it doesn't. Among the claims, trolls for investors, and
testimonials, where is the quantitative data showing that a fractal
antenna is in any way better than a bow tie, in what ways, and how much?
In other words, exactly where is the evidence on which you based your
statement?

The only "evidence" I have is a "testimonial" by the guy who invented it,
on some PBS show. And they claimed that that's how they pack so much
antenna into a box the size of your thumb. ;-)

And, having a passing familiarity with fractals, it just sounds eminently
plausible to me. :-)

Cheers!
Rich

Their advertising budget suggest that they are getting sales and they
do radiate
to the satisfaction of their users �They don't have lumped loads so
where ';s the beef?
Art- Hide quoted text -

- Show quoted text -

It's a folded, folded, folded, folded, folded,... n(folded) unipole
antenna!! ;-)

On Nov 21, 7:04�pm, Rich Grise wrote:

Where I'm sitting here in Whittier, KABC 7 is so strong I can get it
without even a cable plugged in!

Decent power, line of sight (18.2 miles @ 172.2 deg true) will do
that.
Check your email....

-mpm

Art Unwin wrote:

...
Their advertising budget suggest that they are getting sales and they
do radiate
to the satisfaction of their users They don't have lumped loads so
where ';s the beef?
Art

Art:

I am ready to bend over backwards, until I can say different ...

However, how much you wanna' pay me for one of these?

---
|
| -- telescoping whip
|
|
|--------------------- ---
/ |-------------- coax
\ |_______________ --
/ ----- 50 ohm, five-watt or better non-inductive
\ |
/ |
| |
----- ---
--- - -- ground
-

Lifetime antenna, virtually perfect SWR, no moving parts, guaranteed a
lifetime, etc., etc.

AND! I bet I can find some to give testimonials to it being an
"excellent antenna." You know the game ... idiots are easily taken
advantage of ... :-(
BUT-EVIL-GRIN

.... come on, argue something real ...

Regards,
JS

"JB" wrote in message
...


I wonder how the Limo's will deal with DTV in motion.


Ahah! Presently they don't. A big issue for opponents of 8VSB modulation
was poor performance in mobile/handheld (M/H) applications. Straight 8VSB
does not handle "dynamic multipath" well.

However ...

Development of the ATSC-M/H Standard for mobile
and handheld applications is moving forward at a
rapid pace. A critical element of that effort is the
Independent Demonstration of Viability (IDOV).
The goal of IDOV is to ensure that the technical
proposals under consideration can meet the goal
of enabling mobile and handheld services in early
2009.

per http://www.atsc.org/communications/n...r_standard.pdf -

I read some news accounts of supposed successful tests (the "IDOV" ?) this
past spring. We'll see.

BTW, alt.video.digital-tv newsgroup is doing a good job with the TV
transition. Also,
http://www.avsforum.com/ has news, like
http://www.avsforum.com/avs-vb/showthread.php?t=1078353

Joel Koltner wrote:
"mpm" wrote in message
...
"Whitespace devices will also cause great harm to wireless microphones,
particularly older models."

Isn't the estimate that something like 90% of all wireless mics are being used
by folks who technically never had the authorization to use the spectrum
(...that is used...) is the first place? Something like how only radio and TV
stations had the authority to use the standard wireless mic frequencies, but
these days anyone doing professional sound for theater, sporting events, etc.
is also using those same frequencies?


The FCC and the TV broadcasters looked the other way because there is no
evidence that such activity has ever caused any interference. I can get
6 microphones to work in an occupied analog TV channel and neither
notices the other.

The TV Band Devices the FCC has recently begun the process of
authorizing are way more damaging than a 50 mW 65 kHz deviation FM signal.

Luckily, these devices will not be allowed anywhere near where I work.
The FCC has banned them from the 13 biggest cities, and from within a
kilometer of a venue or stadium using wireless microphones. The
proposed rules do not require a Part 74 license for these protections.

Rich Grise wrote:
On Fri, 21 Nov 2008 06:36:32 -0600, Cecil Moore wrote:
Sal M. Onella wrote:
If even poor antennas work well, why all the whining?
I've not had any problems with the UHF circular loop that comes with
standard rabbit ears. The only problem I've had is with VHF channels on
the dipole. I need a weatherproof version of my RS rabbit ears.
Unfortunately, ABC is Channel 7 here in Tyler, TX.

Where I'm sitting here in Whittier, KABC 7 is so strong I can get it
without even a cable plugged in!

It's 50, 56, and 58 I worry about; 2-13 and 28 are covered; I'm looking
forward to seeing if my new bowtie (from that youtube video, but with
ER708-2 x 1/16 filler rod) will pick up PAX on 30. They have some nice
oldies sometimes. (I also have some of the ER708-2 in 0.045".)

I'm gonna solder it together and hold it to the board with brass thumb-
tacks. ;-)

Just for reference: http://www.youtube.com/watch?v=EWQhlmJTMzw

Cheers!
Rich


Ion TV 30 is in Claremont and has a 3.8 Megawatt Signal (elliptically
polarized no less). It should give you a tan in Whittier.

Cecil Moore wrote:
Roy Lewallen wrote:
Sorry, it doesn't. Among the claims, trolls for investors, and
testimonials, where is the quantitative data showing that a fractal
antenna is in any way better than a bow tie, in what ways, and how
much? In other words, exactly where is the evidence on which you based
your statement?

http://ieeexplore.ieee.org/Xplore/lo...number=1610336


If you are a member of IEEE, you can access this paper:

Multiband behavior of wideband Sierpinski fractal bow-tie antenna
Yamini, A.H.; Soleimani, M.
Microwave Conference, 2005 European
Volume 3, Issue , 4-6 Oct. 2005 Page(s): 4 pp. -
Digital Object Identifier 10.1109/EUMC.2005.1610336

interesting paper..

The big benefit (from a cursory reading).. is that you have a more
consistent antenna pattern over the frequency range, which the vanilla
bowtie does not. And a somewhat wider match bandwidth. (mostly extending
it to higher frequencies)

Nothing magic, though.