OT: WiFi hardware question

Joseph Sinclair plug-discussion at stcaz.net
Tue Oct 26 00:11:25 MST 2010


Normally, an Access Point is intended as the base station part of a Wi-Fi network.
It is possible, sometimes, to use one as a wireless bridge (which is what you're describing in connecting it to the ethernet port), but I'd be very leery of using such a low-cost unit in that role; it's not entirely uncommon to see low-end units like that function very poorly or not-at-all.

As for antenna size, a 2.4GHz antenna is generally going to be most efficient at 1/4 it's wavelength of 12.5cm.  Most small devices have an antenna of about that size (around 1.2 inches), and there's little or no advantage to using anything larger.
The larger antennae on some access points and bridges are usually dipole (2 antennae at 3.125cm each in opposition around a common centroid) and aren't actually any better at receiving signal, but they feed into a much higher gain amplifier stage using a differential amplifier which has better signal-to-noise ratios at the cost of using more power (and requiring a dipole antenna).
Wireless N uses VOFDM reception which drops dipole amplification and, instead, uses it's antennae to, receive more power from the original signal via multipath amplification (basically using weaker signals from other angles to amplify the strongest core signal).

You might be better off getting a newer Wireless N USB dongle with 2 (or more) internal antennae for multipath diversity (which usually provides better signal in home environments than dipole amplification) rather than tying the machine to a fixed bridge of uncertain quality.

I hope that helps.

==Joseph++

Steven wrote:
> Okay, this one seems like a no-brainer question to me but I haven't
> dealt with one before. A wireless access point like this one:
> http://www.newegg.com/Product/Product.aspx?Item=N82E16833180035 should
> get better reception with that antenna than one of those little stubby
> USB adapters like this:
> http://www.newegg.com/Product/Product.aspx?Item=N82E16833127272
> 
> My sister's computer is hooking into our wireless using a USB wireless
> adapter about the size of that second link (although it's too old to
> still show up on Newegg, I'm just pointing to something similar in
> size), and it's never had great reception, but lately it's been very
> flaky. Looking over things I realized those access points start in the
> same price range as the USB adapters while having those nice antennas
> that are longer than the USB sticks are even including the USB plug.
> 
> That said, I've never actually used an access point, it's always either
> been a built in laptop adapter, a PCMCIA adapter (which got a lousy
> signal going through two fewer walls than are between the wireless
> router and my sister's computer), or one of those USB wireless adapter
> sticks. If I'm catching how it works correctly her computer should
> simply see it as a plain old connection over the build in Ethernet port,
> correct?
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