[TowerTalk] Fractal Antenna's
jimlux at earthlink.net
Sat Feb 20 15:08:37 PST 2010
Neal Campbell wrote:
> The greatest story on this is from a show on PBS about Fractal Geometry.The
> first half of the show is about how skeptical and belittling the mathmatical
> world was about fractal geometry when it could be proven over and over and
> seen recurring everywhere in nature.
> The second half of the show was about the practical applications of fractals
> and they spent quite a bit of time telling the story of Nathan Cohen who as
> a ham started to wonder if antennas would benefit from fractal design and
> wrote a paper in Communications Quarterly. He kept going, finally starting
> up the Fractal Antenna company which sells antennas it seems in the cell
> phone market, etc.
More correctly, he sells licenses to use the patent, and hopes to get
investors. They probably do make some antennas.
As others have pointed out, there's an infinity of ways to make a
physically small antenna, if you're willing to give up gain or
bandwidth. Fractals are but one, and lend themselves to sexy marketing
Note also that just because the Dept of Defense or NASA buy something
doesn't mean that it actually is any better than anything else. For all
you know, they bought it for test purposes.
There are also rumors that the inventor is fairly assertive, and doesn't
take kindly to folks wanting to do "head to head" comparisons. It's
kind of hard to legally build an example of a fractal antenna to test on
an antenna range against, say, a meander line or loaded dipole without
violating his patent. I don't know, but he could easily put a
restriction on purchasers of his antennas that you not publish test
results from antenna range measurements.
This is like various software companies that have, as a part of the
license terms, that you cannot publish benchmark results from their
The common law exception (viz Whittemore vs Cutter, 1813) in patent law
for "experimental duplication" of the patented article has some
limitations. You can duplicate to perform scientific experiments or to
test the patent's claimed utility. Later, the same judge (Justice
Story) explained more in other cases, basically saying if it's for
profit, it's clearly not in either of the two cases, and because
businesses exist to make a profit, no business can claim the exemptions.
Later cases narrowed the exemption further: "for the sole purpose of
gratifying a philosophical taste, or curiosity, or for mere
amusement" but not for "experiments with a view to the adaptation of the
invention for the experimenter's business, or for the convenience of the
experimenter (say you used the patented device to make your other job
Most interestingly, in Bonsack Machine Company v Underwood in the 1890s,
it was held that using a patented machine for the purpose of comparing
and selling a competing machine were activities outside the experimental
use exemption. So much for making various patented antennas to compare
them on a test range, if you're in the antenna business at all.
Later, the experimental use exemption started to get bigger, but then,
it totally clamped down in the 80s, largely because of some cases with
respect to drug patents. They pointed back to the early 1800s cases and
said the dilettante curiosity expressed by Justice Story was in no way
similar to someone who has any potential gain from the experimentation.
I don't recall all the details, but the bar was set pretty high to be
able to claim the exemption. Even writing a scientific journal paper by
researchers who had no connection to any of the entities comparing the
performance of various patented drugs or techniques was held to be
infringing. Basically, they removed the "intent" aspect of
infringement.. if you duplicate the patented thing, you've infringed,
and basically you have to hope that the patent owner can't establish
significant damages. However, in practice, the legal fees alone in
mounting a defense would probably cripple most folks.
The courts went back to the original "idle curiosity" or "amusement"
and read it pretty narrowly... a researcher writing paper benefits (in
reputation, grant awards, etc.) from the infringement of the patent, so
they can't claim the experimental exemption. There's a case from Duke
University and the inventor of the Free Electron Laser, for instance,
notwithstanding that Duke is non-profit, etc. As one writer commented:
"any experiment that had a specific purpose or goal would fail both the
'idle curiosity' and the 'business objective' tests."
So basically, you can knock yourself out making fractal antennas in your
backyard as long as you don't tell anyone about them or hope to benefit
Therefore.. there's not much incentive to go out writing QST or QEX
articles, is there... Lots of potential downside (defending against an
infringement lawsuit from Dr. Cohen) vs very small upside (a few hundred
bucks from ARRL?).
Think about it.. if you want to experiment and write for QST, there's
lots and lots of topics you could fool with, so why pick one where
you're almost certain to get stuck in a mess.
You could even be bold and do your experiment and put it on a webpage,
with no overt objective other than idle curiosity. And you might get a
letter from Dr. Cohen's attorneys, asking you to take your web page down
(I have heard it rumored that this has happened, but haven't been able
to verify it. It's possible that the letter made an offer the website
couldn't refuse: "we won't sue you, which would cause you to spend
thousands of dollars defending yourself, if you take the website down
and shut up about it")
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