which wireless adapter you think is better? Do big antennas actually help?

[DaRuSsIaMaN]

I'm debating between the
ASUS USB-N53 Black Diamond
and
Rosewill RNX-N600UBE

Do you guys think that giant antennas like the ones on the Rosewill one actually tend to help all that much? Obviously, physics dictates that antennas are necessary. But are big external ones necessarily better than the internal ones on the ASUS device? Since I'm not myself a wireless engineer I wonder if the large antennas are actually kind of a marketing gimmick rather than noticeably beneficial. Thoughts?

***

I need a dual-band adapter for my laptop because I'm currently trying to set up a dual-band router, and I just realized that neither my laptop nor the usb wireless adapters that I already own are capable of 5 GHz. After rebate, the ASUS one comes out to $28, and the rosewill one is currently $20 with a promo code @ egg. The asus one does seem to be more versatile if I use the adapter on the go...

 

[gangolfus]

As a general rule, antenna size is not an accurate indicator of range.

 

[BigBadAl]

True but antenna gain is, to a degree....

Generally speaking an antenna is made a certain size to accommodate the parts of the antenna that is designed for best performance and ideal radiation pattern for any given intended use.

Each 3dB of gain is an effective doubling of power, likewise each 3dB of loss is an effective halving of power.

Range doesn`t exactly double with a 3dB of gain due to obstacles in the real world.

Lets say a router puts out 100mW of RF, put that power up a piece of wire and it will have a range of `x` and an ERP (effective radiated power) of 100mW, probably a little less due to resistance in the wire/connectors etc.

Now if you connect an antenna with 3dB of gain to the same router putting out 100mW the ERP is now 200mW (3dB of gain = doubling of power) if you use an antenna with 6dB of gain the ERP jumps to 400mW (100mw doubled by the initial 3dB and doubled again by the second 3dB)

If you used an antenna with 9dB of gain you`re at an ERP of 800mW. Now obviously you can go on and on and on until you have an antenna 100m in length with 5 million dB of gain and it looks ridiculous, so you gotta stop somewhere.

In short they do help, but you need to balance performance with aesthetics....

 

[DaRuSsIaMaN]

Nice. Thanks for the discussion.

So, that makes sense for power emitted from a router. However, in a wireless adapter I'm more interested in picking up the signal that has already been emitted from the router. Obviously, I have to transmit signal from my end, too, but the download direction is more important. Does larger antenna size and gain translate in a clear way to being able to pick up a weak signal better in this context?

 

[BigBadAl]

Hmmm, yes and no....

Gain works in both directions transmit and receive but remember, in the real physical world, there are obstacles and interference.

You could use a bi-directional amplifier into a serious antenna with 12dB of gain on the router end.

but then you`d need something similar on the other (client) end for your laptop/smart TV/ whatever. That in itself would not be convenient all stuck to the back of your Ipad, not to mention the battery life would be useless!

So no, jacking up the `output` from the router will only work to a really really small degree.

Best option, go for `n` draft wireless kit.

I went from a WRT54G with DDWRT and 2x 9dB antennae to a Ubiquiti Unifi access point.

That single step alone improved my wireless coverage/throughput/stability no end! The AP isn`t even mounted properly but locations that would be considered `behind` the access point get fantastic coverage.

My phone picks up my wifi as I drive into my street past my house. A neighbour can pick up my wi-fi on his smart TV... he lives 2 houses down from me, that would be considered `off-to-the-side-through-2-additional-houses`.

You choose!