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Old Geek Invents New Stick
the morgawr writes "According to the EE Times and Science Blog, a scientist at University of Rhode Island has developed a new type of antenna design that, by increasing the efficiency, performs as well as the convential quarter-wave design but is only 1/3 as large."
Will we see this at next year's WiFi Shootout?
Kinetic stupidity has a new brand leader: Allen Zadr.
The great thing about antenna design and RF theory is that all of the design happens in the mathematics domain, so all designs are infinitely scaleable. The only hitch may be in manufacturing, since small designs can be affected by molecular structure (or at least moreso than larger designs...)
The articles did mention that it could be used in the frequency bands that cell phones use, so you're in luck!
And actually, it would improve BOTH battery life and reception, since receiving a signal doesn't require any more or less power based on the antenna or incoming signal strength (excepting preamps). All other things being equal, if you decrease the transmit power, increase the antenna gain (which gives a gain for both receive and transmit), then you use less power overall, but can output an equivalent signal.
Improved reception is an unrelated (to power consumption) bonus.
I was just reading about something like this just last night.
I'll bet it ends up working on the same principle that Bill Beatty is talking about when he got to thinking about why it is that an atom can absorb light so readily even though the size of the atom is such a small fraction of the wavelength.
Relevent articles:
Energy sucking antenna
On the Possibility That Electromagnetic Radiation Lacks Quanta of Any Kind
Nearfield coupling and tuned circuits
Hmmmm.. a 'ham' making new antenna discoveries...sounds familiar:-)
It is not physically possible to attain a moderate Q or low Q, thin monopole --antenna-- which is 15-18 inches on 21 MHz and is efficient. This is not a statement against K1DFT, or anyone else. It is a statement of fact, based on the physics of very electrically small antennas, and many years professionally devoted to pursuing such issues. K1DFT has apparently pursued a path long since traveled by many others, and not only myself.
Occasionally, in some form factors, it is possible to trade efficiency for gain, but this is too short for that. And so much for bandwidth.
Great care needs to be taken to remove multipath effects in the measurement of gain, and greater care needs to be taken in equating measured comparitive gain with actual antenna efficiency. Based on this anecdotal report, there is no evidence presented that such issues could be removed in the measurements.
Radiation resistance results from an antenna's sampling portions of radiating waves. A short antenna samples a small portion of the wave--and not from the peak, unless the electrical length is 1/4 to 1/2 the wave or more. Multiple current maxima do help increase radiation resistance. Efficiency is derived from the ratio of this radiation resistance to the total resistance--which includes ohmic losses. Distributed discrete loads are moderately lossy, and one would require load Q-factors of 1000 or more to attain even moderate Q antennas with high efficiency.
The optimization of distributed loads in monopoles is an old technology, recently aided via genetic algorithms. I recall, for example, some good work on this approach published in 1996 by Boas et al. Before that, R.C. Hansen made fundamental efforts into such understanding, as well as others. MATLAB is also a poor tool for this, because it is difficult to assess losses properly.
Another concern is: what is radiating? In some cases, ground planes (counterpoises) do, indeed, radiate in the far field and are thus part of the antenna. The monopole 'antenna' is often a loading mechanism in this case, and contributes little to the radiation. There are commercially used 'antennas' that are 1/10 th the height of a 1/4 wave or less; are broad/multiband/ and so on. This is not new. They are used in wireless LAN; RFID; and cell phones; and many other places.
Many here are aware of my efforts in fractal antenna technology--which started in a similar radio amateur vein. Although I applaude continued efforts into antenna experimentation through ham radio, I must confess that my educated opinion is that nothing new has, or will be, attained by such efforts. The state of the art is often not public, and far outstrips what is commonly available in, for example, amateur radio publications. I would enjoy being wrong, however. In fact, I'd get a great kick out of it.
It's sure fun to read about though, and experimenting is fun to do.