antenna-theory.com

[generalfox@generalfox.com]

I've read (theory) where you can apply a voltage to an antenna to make it electrically larger using the near field, and this made me wonder if you could make an antenna both larger, and able to receive extremely weak signals, by applying a voltage to it.

There is a website that describes some research based on Telsa's research (http://amasci.com/tesla/tesceive.html) that I am using as a reference.

Could anyone shed some light into this for me? Does this idea have merit?

[admin]

Definitely not for antennas humans would use (i.e. in products). Looking on the atomic scale there could be some effect.

[generalfox@generalfox.com]

Thank you for your response!

I am curious as to what aspects of the article you feel fail to pass valid theory for larger antennas?

[helix]

The article you linked to is drivel. (Citing Tesla ought to be your first red flag. Tesla was certainly a pioneer of electrical engineering. But many of his futuristic ideas have been shown to be unfeasible or impractical. His legend has grown since his death but it is no more than that -- legend. Thousands of scientists and engineers and billions of research dollars have been spent on some of his ideas in the past 75 years -- e.g., directed energy or "microwave death ray" -- and they have been more or less shown to be unfeasible in the sense that Tesla intended. Anyway most hacks/quacks start by citing Tesla and pretending that he knew some secret that modern EE's don't know...)

Anyway, w.r.t. the article, the author is fundamentally mistaken. For one, the reason atoms interact with light despite the difference in length scale is that there are A LOT of them. ONE molecule of SiO2 indeed does NOT interact with a beam of light much at all, but a macroscopic ensemble of them (e.g. a prism) does.

Furthermore, the idea of near fields due to a transmitted (outgoing) wave on an antenna interacting with an incoming wave is at odds with the concept of linearity (and therefore super-position). If you're using nonlinear materials in the antenna, then in principle there could be an effect (but not necissarily a useful effect). But since incoming field is weak, then that field is only a perturbation, and the problem can be once again linearized.