Log-Periodic Antenna Design

[Cecil Moore]

No, that's "Best Regards's". It's the possessive, not plural, form of
"Best Regards". I think the grammar is part of the same dialect as the
verb "destinate" (as in "I've just destinated"), but you'd have to ask
Richard about that -- he's the one with the English Lit degree.

My Webster's unabridged dictionary gives the following
examples of the correct way to pluralize numbers.

"figure 8's", "the 1890's", "the 20's"

73 is a number that stands for "Best Regards"

73's would be "Lots of Best Regards".

 

[Cecil Moore]

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/login.jsp?url=/iel5/10686/33800/01610336.pdf?arnumber=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

 

[Cecil Moore]

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.

 

[Dave]

Dude! Awesome! And this one doesn't even have a reflector!. I
wonder how far I should hang it in front of the venetian blind. ;-)

Thanks!
Rich

I don't have time to search for it, but there's also a dual quad UHF TV
antenna that's easy to build with the same kind of materials. I prefer
steel tie wire to coat hangers because it's easier to work with.

 

[mpm]

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.

Now that the FCC has given a green light to whitespace device
deployments (particularly those that rely solely on spectrum-sensing
technology), you may find you need a better antenna than a simple
loop, bowtie or coat hanger.

For those of you who are not following the issue, a quote in this
week's TV Technology pretty much sums it up:

"MSTV (Maximum Service Television) told the Commission Oct 31 that the
least the FCC could do is subject the devices to rigorous testing
beforehand and ensure fair and reliable tests to prevent interference
to DTV. In a filing, MSTV also attacked the FCC proposal that a
device should be able to detect signals as low as -114 dBm, a level
MSTV equated with setting a smoke detector to only be able to detect a
raging fire."

Whitespace devices will also cause great harm to wireless microphones,
particularly older models.

-mpm

 

[GregS]

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?

Roy Lewallen, W7EL

I don't have data. I think the home made TV antenna in the video, is very much like a bow tie,
and could have better bandwidth by making the elements different lengths. The gain factor
is going to be narrow band since the feed length is constant. I would have also used 12ga
copperweld or solid copper. You can also get closer to fractal by using many more different
sized elements.

greg

 

[Charlie E.]

It doesn't.

I have two converter boxes, one Magnavox, one Zenith. I just now tried my
local stations with them using a straight 24-inch alligator clip lead as the
antenna. Location is a residential garage in the San Diego suburbs. Stucco
walls, metal garage door closed, overhead fluorescent lights on.
Transmitters in three different locations.

All the UHF locals came in, 10 transmitters with about twenty total
programs. The one low-power VHF did not. Looping the clip lead back and
clipping the end to the F-connector produced about the same results. (Lost
one TJ station.)

When I "upgraded" to a POS 2-bay bowtie in the rafters (about 8 feet up),
all eleven locals came in, plus KCBS from LA . On the Zenith box, arguably
a better unit, I got two more LA channels, although one of them had some
intermittent freezing and tiling.

If even poor antennas work well, why all the whining?

"Sal"
(KD6VKW)

Well, they work if you have a good, strong, signal, but if you don't
fuhgetaboutit!

Here in the desert, all the stations are co-located only about 6 miles
from here, but there are two little problems. One, 80% of the valley
population is located to the south, so they have configured the
antennas with their major lobes that direction, and second, there is a
Edmom Hill between us and the antennas! You can't even get analog
broadcasts here, much less digital!

Charlie

 

[JB]

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

Multiband behavior of wideband Sierpinski fractal bow-tie antenna

And if you aren't a member, you aren't in on the joke?

With all the added capacitance to the elements, I have little doubt that
there would be lots of resonance's, and it would be cool to choose the
geometry to bring about the proper feed point impedances, but these things
can never be gainful with all the losses introduced.

Neat idea for specific applications like little pocket toys, but certainly
not the answer to everything.

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

 

[JB]

I don't have data. I think the home made TV antenna in the video, is very
much like a bow tie,

Comparable to a 4 bay bowtie. Maybe 6db gain. Brazing rod would be a
little lighter and wouldn't rust. Would work much with a reflecting plane
and above the house clutter.

Twin lead could make a comeback since there won't be such a worry about the
low band interference issue. Actually much less loss than coax. I may yet
change over to 300 ohm window line on my bigazz deep fringe at 40ft and
switch it to the ham shack for 6/2m SSB work and DTV DX. TV DX won't be
dead, you will just have to know where to find it

 

[GregS]

Maybe... when it's new, of the right type (e.g. tubular), clean, dry,
and carefully installed.

My understanding is that the performance of 300-ohm twinlead
installations tends to deteriorate significantly after a few years
(sunlight and ozone attacks the twinlead, and dirt and pollution
builds up) and during wet weather.

Last time I used twinlead, except for fiddling around, was on the family
TV antenna installation using an Allied Radio Corodized VHF antenna,
with Beldon Super Permaohm 300 ohm shielded twinlead. Good stuff.

greg

 

[Rich Grise]

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

 

[Art Unwin]

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

 

[Rich Grise]

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:

Cheers!
Rich

 

[mpm]

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!! ;-)

 

[mpm]

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

 

[John Smith]

...
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

 

[Sal M. Onella]

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 www.atsc.org/communications/newsletter/2007_december_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

 

[Dave]

"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.

 

[Dave]

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:

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.

 

[Jim Lux]

http://ieeexplore.ieee.org/Xplore/login.jsp?url=/iel5/10686/33800/01610336.pdf?arnumber=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.