I'm a wireless novice, and I'd like to increase my 802.11 wireless signal strength and range. In particular, I want greater strength through walls. I understand that antennas focus signals, not strengthen them. I see a lot of 2.4Ghz signal amplifiers for sale. If I purchase one of these and hook it up to my antenna will this increase range and strength? Or do I mis understand the technology?
How many walls? What type of walls? If it's drywall or wood, you have a chance. If it's concrete, steel, aluminium, or foil backed insulation, forget it.
Correct. Antennas do not generate any RF. The merely redirect it.
Many are totally illegal. Look for the FCC type certification (if in the USA).
Have you looked at the prices for these amplifiers? Even the cheapest is $100 plus.
Antennas improve the signal strengh in both directions. Amplifiers only boost the signal in one direction. In the reverse direction, you're limited by the transmit power of the non-amplified device. This lack of symmetry results in the range being limited by the weakest transmitter. The receive RF amplifier in the power amp does little except eliminate any coaxial cable losses.
Suggestion: If you're trying to get answers from newsgroups and mailing lists, kindly supply:
What are you trying to accomplish?
What do you have to work with? (Existing hardware and RF environment).
What have you tried and what happened? (Not applicable in this case, but very useful for techy problems).
My guess(tm) is that you're trying to improve the coverage to parts of the house. Going through walls is not a great idea. One wall is usually no problem. Two is somewhat difficult. Three or more is possible but difficult to maintain a reliable connection.
The easist and simplest antenna is a reflector behind your existing wireless router or access point. See:
work well and are really cheap.
If you're able to run CAT5 to some place near the area you want to cover, a 2nd access point will work.
If you can't run CAT5, it may be possible to use a WDS (wireless distribution something) repeater if your existing unspecified hardware supports WDS.
If you can't run CAT5 and don't want to deal with repeaters, it's possible to build a repeater/bridge using power lines as a backhaul. See:
Better to go with Antenna approach and when you stop and think about it you can understand why. Let's say you can boost your AP output to 10 Watts (way illegal etc, just supposing here) so you get a good range boost and great signal out to your wireless computer. Question have you improved the link from the laptop back to the AP? If not then what have you gained? Remember your network is a two way converstation, both sides need to be able to hear each other clearly. The chain is only as strong as the wealest link, to toss in a cliche. The reason improved antennas help is they boost not only output in a fashion, but they also improve 'hearing'. If the Laptop can 'hear' the AP, but the AP can't 'hear' the Laptop, you are out of business, no connection etc.
Before even working on the antenna, try literally moving the AP a few inches in some direction, same with the laptop if you can. You would be amazed at what can happen with this kind of tweak in your house. 2.4GHz really won't go through a solid wall, what happens is the signal finds a crack(s) or hole in the wall or bounces off various walls/objects in the house until it hits the antenna on the laptop (if it makes it that far before dissipating). By moving things around you might improve the path to the wall crack or reduce the number of bounces off walls and such. May not work, but that is the cheapest and easiest approach and the one I recommend strongly as a first resort.
Others here like Jeff Lieberman can give you good info on antennas and other things to try, but pass on the amplifier, it looks good at first glance, but when you really think about what has to happen you can see it is really no solution at all.