which wireless router?
kassube at gmx.net
Tue Feb 26 07:37:45 GMT 2008
Billie Walsh wrote:
> Larry Hartman wrote:
> > It has been
> > pointed out to me along the way that if two antennas are operating at
> > the same frequency at the same time, that when they are a given
> > distance apart, the signal strength perpendicular to the axis of the
> > two antennas greatly increases, while the signal strength along that
> > axis reduces.
That is correct, as long as you have equal cable lengths between the
transmitter and the two antennas. The best distance would be multiple of
> > This theory is why truck drivers employ two antennas for their CB's.
> > In their example the typical width of a tractor cab is about the
> > right width necessary for signal strengthening in front of and behind
> > the truck. As was explained to me, the improvement can sometimes be
> > measured in terms of miles.
Nice idea - the distance would be 5.5 m.
> > Depending on the electronic environment, the employment of two
> > antennas may not always generate interference, but may be
> > complimentary.
The term is still "interference", constructive interference in
forward/backward direction and destructive interference to the sides. See
> > Dunno about Linksys or any other vendor, but it is a
> > consideration.
> Considering the difference between 27MHz, CB frequency, and the 2.4GHz
> of wifi the spacing on a Linksys may be just about the equivalent
Sure, that could be done at the WLAN frequencies as well, but then the
antennas would have to be fixed and mechanically parallel. However, you
can rotate the antennas in 2 axes and the distance is not right. While
you could compensate for the distance with the cable lengths, I don't
think the antennas are connected in parallel. The distance of the
antennas is 0.15 m, which is 1.25 wavelengths. For antennas in parallel
it would be more useful to have a distance of 1 or 1.5 wavelengths. But
the distance is best suited for diversity reception. With a given
distance of 1.25 wavelengths, if one antenna is in a position of
destructive interference, the other antenna usually is in a position of
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