3 ms·
FWIW when you're closer to an antenna than the wavelength, you're not just seeing normal Gauss's law drop off, you can be looking an an evanescent wave [1], whi
by doubleunplussed 7y ago
FWIW when you're closer to an antenna than the wavelength, you're not just seeing normal Gauss's law drop off, you can be looking an an evanescent wave [1], which does indeed fall off exponentially (well, depends on the exact shape of the antenna).
I've designed a short-range 'antenna' that is intentionally not impedance matched to the vacuum, and radiates very poorly - but the RF intensity close to the antenna is very high because of this effect.
[1] https://en.m.wikipedia.org/wiki/Evanescent_field https://en.m.wikipedia.org/wiki/Evanescent_field
- jcims 7y agoCool. Could this be used for wireless charging and/or less snoopable RFID/contactless replacement?