WIFI Antennas: What's the difference? Impact of change?

Hi,


I have a DLink DIR-451, but when it arrived there was no antenna in the box. As I bought it secondhand, I could not complain. I am however struggling to find details on the OEM antenna, and as such I just went ahead and bought a decent 6dbi antenna... but what does that really mean?

I know that dbi is decibels isotropic, meaning db in all directions, but what qualifies as a decent dbi? Do you measure the area you require covered and get a qualified antena based on that? And if so, what is the range of a 6 or 12 dbi antenna?

Furthermore, if a factory antenna is only 3dbi for instance, and I change it to a 12dbi, do I risk damaging the device/router?

These may sound like silly questions, but I seriously have no idea and Google isn't giving any direct answers...

Thanks!

Okie dokie

You're over cooking this problem. No harm in it, but relax and take deep breaths.
ANY lil' WiFi antenna will do just fine in there... I interchange them all the time because my cat likes to knock routers off the table and they always break at the bendy bit. So it doesn't have to be D-Link... but... i know PC stores do sell those little guys.

If you're looking to improve your range (bear in mind that the router you have is not designed with range and speed in mind), you could put a larger antenna on. It won't harm your router at all... I had a similar router and plugged a 12db antenna in with an extension because at that stage my router was sitting on the floor.
To be accurate AND NOT OVERSPEND, network techies and antenna wizards will work out a dbi gain vs area coverage factor and go from there if a more involved, multiple antenna, setup is needed... but for your applications, with your router, any commercial antenna will do nicely. If you do get something more hectic than a little bendy one, read up on it first because a lot of them make promises on the box and then don't work so well. They also tend to be very directional.
I found the higher up the router went (as in... on TOP of the cupboard and not under the desk)the better the overall reception was... just as an aside.

dBi is not like that at all! Here's a quote from Wikipedia:

dB(isotropic) – the forward gain of an antenna compared with the hypothetical isotropic antenna, which uniformly distributes energy in all directions. Linear polarization of the EM field is assumed unless noted otherwise.

Click to expand...

Most of the antennas (if not all) are specified in dBi, even the directional (non-omni-directional) ones.

The higher gain antennas would use the same amount of power. The difference between the high and low gain antennas are simply the vertical and horizontal angles that they cover, so the higher gain antennas typically don't cover a large vertical angel - like this 7dBi Whip Antenna (Reverse Polarity SMA) one has a vertical beam width of 18'. You also get directional antennas which has much higher gains, like 24dBi Grid Antennas, but their vertical and horizontal beam widths are very very narrow.
The antennas are like having a reflector on a flash light. If you install a reflector that would have a wide focus, then the light intensity would be pretty low, where as if you have a very narrow focus lens then the light intensity would be much much higher even though the flash light would draw the same amount of battery power.

At Scoop Distributions, the highest gain omni-directional antennas that I've seen has 9.3dBi gain.

I think you need an antenna with a R/P (Reverse Polarity) SMA connector to go with that router. Also make sure that you're getting one that is designed for the 2.4GHz frequency range.

Ah, thank you both for clearing that up. I bought a 6dbi antenna from New World in Menlyn Mall, Pretoria which seems to be working fine. I was only worried that if a router comes with a 2dbi antenna and I stick on a 6dbi that it might damage the router. I know the idea sounds silly, especially since I actually used to be a technician before I went the software route.

I just don't have the cash for another router. Rather safe than sorry! ;-)