The following guide is intended to give the reader a better understanding of how to increase signal coverage using several techniques.
[_] Wi-Fi Router or Access Point ideally with interchangeable antenna
[_] Software or hardware network analyzer (Channelizer is good), or a heat mapper.
[_] Your Wi-Fi Routers manual(for looking up specifications)
1. The first step, whenever hoping to improve your wi-fi, is to know exactly how your current implementation is functioning. Create a drawing of your home or environment, and record the Signal-to-Noise Ration or the Signal Strength found throughout your environment. [Signal-to-Noise ratio should be a positive number, the higher the better, 20db or more should give you a good quality signal. Usually a Signal Strength of -80dbm or higher(-70, etc.,) will give you a good signal .]
2. Using the drawing that you created above, look for the locations that have the worst signal quality based on the specifications given. This drawing gives you a visual representation of your Wi-Fi quality and something to compare against after making changes.
3. Use the following guidelines to help improve your wireless signal:
----Your Access Point(AP)\Router should be located as centrally as possible within the area you are trying to cover.(If you have your AP at an outside wall, this will not only effect your area coverage, but also represents a security risk[Having an omni-directional antenna by an outside wall sends a large amount of your signal out of your home.]
----If you are trying to cover a single-level, and having difficulty even with your AP centrally placed, you may need to exchange your antennas. If you check your AP's documentation it should tell you what your antennas dbi rating is, most consumer grade AP antennas run around 2 dbi [ dbi is essentially a measure of the antennas amount of focus. Think of it like the lens on a flashlight it focuses all of the power in the direction you want. ] If you have a standard antenna you could try changing it to one with 5 dbi which will give you about 25% more signal coverage area. If you need to cover a substantially larger area, say about twice the size, you'll need an antenna with at least 8 dbi for an omni-direction antenna.[You will want to add an antenna for each of the antennas your AP came with(802.11a\b\g can get away with one new antenna due to their use of switched diversity.)
----If you are trying to cover a multi-level home, you've already moved the AP to the central level and still having difficulty covering your area try the following: Adjust one of your antennas so it is not aligned with the others; If one antenna is vertical, try positioning the second horizontally. [Antennas cover specific areas so tilting one or both may give you better signal reception.] If you have a large home, it may be possible that a single AP will not provide full coverage(See a tutorial on setting up an Extended Service Set which will allow you to setup multiple AP's for a single network. If you do this, you can put AP's one level apart and usually get good coverage. When setting this up treat the level the AP is on like a single level home.
*The above graphic represents the signal spread of a wireless signal coming off of an antenna. The first graphic(left) represents looking at the antenna from the top, the second(right) show the antenna from the side. The signal is strongest at the point it is farthest from the center of the graphic\antenna.
----The above options are focused primarily on omni-directional antennas(antennas meant to cover the entire area around them[Even omni-directional antennas don't cover areas directly above or below them very well but off to the sides is their main focus.] There are also two other primary antenna types, semi-directional and highly-directional. If you can't put your AP in the center of your home, a semi-directional antenna may be the way to go. Semi-Directional antennas usually focus the signal in a 180 to 90 degree arc, so you can prevent losing signal out of your home. Highly directional antennas will rarely be needed in a home environment as these are usually made for connecting two points over a long distance, or for shooting wi-fi down a long hallway(100yards or more.)
----I've got this power setting in my AP, can't I just turn up the power and cover my area? Sure, but turning up the power isn't always the right solution for the following reason: What power does your lowest power device transmit with? If you can't answer that information you should look, it can have a dramatic effect. By turning up the power your AP can cover a larger area, but can your device respond? Most wireless devices transmit with lower power to save battery hence they can't push a signal back to your AP powered by mains voltage. Getting a bigger antenna is usually a better bet as it amplifies\focuses signals in both directions send and receive (more power only works when sending.)
Final thoughts, when using 802.11n\ac you really need to use the same type of antenna for all reception points, this is due to the technologies needed for getting the higher speeds you paid for. You can potentially intermix antenna, but it will cause a sever drop in signal throughput, if not completely break your send\receive ability.
Covering a flat plain one story home is easy, multi-story large homes are not. A single AP is just not meant to cover a large area on its own; the limitations placed on us by the FCC and manufacturers, protect not only you but your neighbors [these are microwaves after all.]