why antenna work?

Hi
I want to buy a wifi antenna for my 802.11g router, but the
antenna will not amplify the signal, so why it works?

thanks
from Peter ((E-Mail Removed))

<(E-Mail Removed)> wrote in message
news:(E-Mail Removed) oups.com...
| Hi
| I want to buy a wifi antenna for my 802.11g router, but the
| antenna will not amplify the signal, so why it works?
|
| thanks
| from Peter ((E-Mail Removed))

Climbing a ladder does not make your eyes stronger but does give you a
better view.

On May 5, 8:09 pm, cmk...@hotmail.com wrote:
> Hi
> I want to buy a wifi antenna for my 802.11g router, but the
> antenna will not amplify the signal, so why it works?
>
> thanks
> from Peter (cmk...@hotmail.com)

Maybe because the antenna doesn't come with an amplifier? If it does,
try plugging it in.

All physically realizable antennas have gain, ask specific more
question as to why work.

I always figured if God didn't like antenna gain, He wouldn't have
created earlobes.

(E-Mail Removed) hath wroth:

>I want to buy a wifi antenna for my 802.11g router, but the
>antenna will not amplify the signal, so why it works?

Antennas do not generate or amplify anything. What they do is
redirect signal that would normally go in unwanted directions, to the
direction that you want the signal to go. A tolerable analogy is a
garden hose nozzle. You can set the nozzle to a fine wide spray, or
to a pointed narrow stream. The volume of water delivered in both
cases is the same and is the transmit power.

As the stream gets narrower and narrower, it will go farther and
farther, which is the whole idea. How much farther is a function of
this directionality or gain. In RF terms:
+6dB = 2 times as far
+8dB = 2.5 times as far
+12dB = 4 times as far
+24dB = 16 times as far

You might find the FAQ for alt.internet.wireless worth skimming:
<http://wireless.wikia.com/wiki/Wi-Fi>

Another reason to install an external antenna is that your RV probably
has aluminum sides and foil backed insulation in the walls. No RF is
going to penetrate that much metal. So, you're only alternative for
getting a decent connection at the RV park, truck stop, or coffee
shop, from the RV, is with an external antenna. Highly directional
antennas are also very useful for eliminating interference from nearby
users and systems.

--
Jeff Liebermann (E-Mail Removed)
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

The garden hose analogy is a good one, Jeff! I'll have to remember
that one.

Pete

(E-Mail Removed) hath wroth:

>The garden hose analogy is a good one, Jeff! I'll have to remember
>that one.
>Pete

Thanks, but like all analogies, it somewhat fails in the end. The
common garden hose cylindrical nozzle changes orifice area with
different spray patterns. Therefore, the flow rate (tx power output)
will be larger with a stream than with a spray. I got into a debate
over the issue many years ago. Rather than do the calculations, I
convinced the local grade skool brats to do a quick measurement. Well,
it wasn't so quick and bribes were required for motivation, but the
experiment was successful. I had them build a really crude paddle and
counter flow meter with all the technology that could be borrowed from
the neighborhood landscape contractor. I have photos somewhere. There
was something like 50% more flow with the nozzle in stream than in
spray. However, when we tried different style nozzles, there were
some substantial differences. The more expensive nozzles, that
resemble a fire hoze nozzle with a handle, have almost a constant flow
rate with any pattern. Despite being not exactly perfect, it's good
enough for explaining how antennas operate.

--
Jeff Liebermann (E-Mail Removed)
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

(E-Mail Removed) wrote:

> Hi
> I want to buy a wifi antenna for my 802.11g router, but the
> antenna will not amplify the signal, so why it works?
>
> thanks
> from Peter ((E-Mail Removed))
>
Hi,
Ever heard about antenna gain, radiation angle, pattern(horiz. vs vert.)
as an example?
Antenna theory is very complex subject which needs lot of real world
experiments.

Dana wrote:

> <(E-Mail Removed)> wrote in message
> news:(E-Mail Removed) oups.com...
>
>>Hi
>> I want to buy a wifi antenna for my 802.11g router, but the
>>antenna will not amplify the signal, so why it works?
>
>
> Antenna has gain. Think of it as concentrating the energy.
> Some antennas have unity gain, and by adding elements to the antenna you can
> increase its gain.

http://www.amazon.com/exec/obidos/AS...-bestellen1-20

Is this what you're looking for?
LZ

OK, you guys said the antenna concentrating the energy to a narrow
direction. But how does the omni wifi antenna work? why it has a gain?

I connect my linksys 802.11g router to a TV antenna (like this one
http://www.granbytv.com/3671__Antenna.jpg) by using a normal wire. The
wire is just a very normal copper wire. The result is : i don't see
the signal become stronger. I think i need a dish antenna. Any idea?

thanks
from Peter

<(E-Mail Removed)> wrote in message
news:(E-Mail Removed) oups.com...
> OK, you guys said the antenna concentrating the energy to a narrow
> direction. But how does the omni wifi antenna work? why it has a gain?
>
> I connect my linksys 802.11g router to a TV antenna (like this one
> http://www.granbytv.com/3671__Antenna.jpg) by using a normal wire. The
> wire is just a very normal copper wire. The result is : i don't see
> the signal become stronger. I think i need a dish antenna. Any idea?
>
> thanks
> from Peter
>
Your TV antenna isn't resonant at the right frequency, the impendence is
mismatched, if you have an amplifier in the TV antenna line it may be
filtering out the WiFi frequency and a whole lot of other possibilities.
Bottom line is that your TV antenna isn't designed to work for WiFi.

Omni directional antennas can also have gain. A "5/8 wave length" vertical
antenna has gain, but is not directional in the sense "concentrating energy
in a narrow direction".

http://www.qsl.net/w4sat/five8th.htm

There are lots of books out there on antenna theory and antenna
construction, but you probably don't want to go into the subject far enough
to understand what does what and why. Many variables have to be considered
such as wavelength, impedance, reactance, height above ground, and many
others.

A simple WiFi antenna mounted on top of your RV may well do what you want to
do.

Ron