Re: Radiation from Wireless LAN vs Bluetooth PAN

On Wed, 26 Apr 2006 00:24:52 GMT, Jeff Liebermann
<jeffl@xxxxxxxxxxxxxxxxxxxxxx> wrote:

Marconi duplicated many of Heinrich Hertz's experiments while still in
Italy. Hertz's spark propogation experments were done with a full
wave circular loop antenna, with metal balls at the ends to show the
spark and act as somewhat of a capacitor. The approximate resonant
frequency of his loops were about 300MHz. Not exactly microwaves, but
close enough.

Early microwaves.

http://www.wa1mba.org/micros.htm
"Surprisingly enough, some of the first electromagnetic experiments
conducted by Heinrich Hertz in 1886 and also by Marconi used
frequencies near the microwave region - some around 500 MHz and
some even in the multiple GHz (Gigahertz) region."

J.C. Bose followed Heinrich Hertz with microwave experiments in the 5
mm region (about 30GHz) in 1895.
http://www.tuc.nrao.edu/~demerson/bose/bose.html
His experiments use most of the common waveguide components in use
today. Don't get the idea that microwaves are a recent invention.
They were the original radio physics and only replaced by lower
frequencies when scientists and inventors discovered that the lower
frequencies were more useful for long range communications via
ionspheric refraction.

Microwaves have been around longer than HF/SW broadcasting.

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