How to Get a better WIFI Signal

WIFI Signal

How to Get a better signal,  How to Improve Your WiFi Security  
Troubleshooting Your WiFi Security
Tips, DIY antenna, build your own antenna 

Radio Frequency (RF) is not a simple as it looks, many complex parameters are playing against you.
As I am not a RF engineer, so I'll try to keep it simple, just for the rest of us.

WIFI 101

 Your WIFI is basically a radio, it transmits radio waves between the router and your computer.  WIFI was not made to transmit data over very long distance, it's "fragile" generally speaking, a lower frequency carries better over distance but no so well as for bandwidth, the higher frequencies have a lesser range and are more sensitive to attenuation from solid objects (wall, trees , etc ) 

A 802.11b/g WIFI uses radio frequncy between 2.4 and 2.4835 gigahertz (GHz)  (5GHz for 11a)
The 2.4 and 2.48 are divided in 14  "Channels"
The "Channels" are 22 MHz wide but only separated by 5 MHz, hence they overlap.
Out of those 14 Channels, only 11 are used in the USA, 13 in Europe and 14 in Japan 

A little picture will clarify...

As you can see now, all channels overlap but 1,6 and 11 (in green) do not overlap.

If you live in a crowded area, (WIFI speaking) and everybody use the Channel 6, it will create a lot of interferences.  Ditto if you are the only one to use 5, and everybody around you is on 4 and 6.
If you are in USA, only use 1-11. For Europe 1-13, and Japan 1-14.
When you ask KisMAC to scan Ch 14 in USA, you are almost listening to your microwave: Your common kitchen microwave use a 2.5 GnHz frequency. Avoid that, it may lead KisMAC to panic a little and hang out.

Noise To Signal Ratio (NSR)
Noise is the pollution. The lesser the noise, the better.

You can test your Channels, noise interference with a program called AirRadar.  ( Shareware )With a simple test, Air Radar will tell you which Channel is better for you and which ones have the highest NSR






You can also use AirGrab, no Self-Test, but free and you'll be able to see your NS

Geting a better WIFI signal, Troubleshooting

Your common kitchen microwave use a 2.5 GHz frequency, hence try to stay away from a working Microwave.

RF (Radio Frequencies) will penetrate or bounce around object depending on the density of the object and on the RF frequency.
Best is an open line of sight, worst would be behind a lead wall.  In between, you can move your antenna up or move away from those aluminum venetian blind.
Getting a Good wlan adapter (less than $39) will often resolve all your issues and boost your reception/signal
The output power of the Alfa is 20 times superior compared to your average Airport Card.
I improved by a Factor of 25 compared to my Airport Extreme.

Making your own signal booster (DIY Antenna) can be a 5th grader project and be done in 15 minutes.


How to Improve Your WiFi Security

This is no secret: WEP is weak and can be cracked very easily.  Whatever is your password, it will take me between 2.7 seconds and 2 hours to crack it.  The only solution for a safe WIFI is to not use WIFI.
Let me explain:
There is no "Safe:  Safe is a Swiss Bank inside a SuperMax Prison inside the NORAD Command Center.
Safer  is different:  WPA is safer. Much safer than WEP, but has a vulnerability. It can be cracked.
In the case of WPA, if cracked, it's your fault: the password used was guessed too easily.

As a matter of fact, I am going to be very nice:
If you can find your password in this list, it's probably a very bad sign. So, look for file named "Rockyou list" and check it against your password.

After that, you have two solutions in hand: Improve your Password / Passphrase or use a Cable.
If you still want to go WIFI, then the next best step is to use KisMAC and Wireshark to see if someone has cracked your WIFI, or is trying to crack your WIFI.  Yes!, you can tell ....

Cable Vs. USB For WIFI

Cable Vs. USB For WIFI


WIFI Best Practice:  Coaxial Cable or USB extension?

Coaxial
Coaxial cables for antenna have a little issue: The loss of Signal.
If you buy a cheap cable, you'll have a cheap result and the cable will absorb some of the signal, the longer the cable, the greater the loss.
To be noted:  dBi or signal strength is a logarithmic value, a loss of only 3dBi means in fact that you have a 50% signal loss.  Regular Coaxial cable cable would be my very last choice. 

Low Loss Cable
Low Loss Coaxial Cable  Better than the previous, but more expensive. About $30 for 8m feet, and you still have a loss.

USB

By far, the best choice when possible: No Loss and much cheaper than a Low Loss Cable.  About $10 per 15ft for
So, when you can, Extend the USB cable instead of extending the Antenna Cable.

If you have made the mistake to buy a Hawking,  Edimax, D-link or any other USB Stick, don't extend the Cable to the antenna, extend the USB to the USB Adapter and keep the coaxial cable as short as you can.
If you haven't made the mistake yet,  get an Alfa AWUS036H or a Alfa AWUS036NHR ,  I pulled a signal @ 15km with one of those babies :)
Check this page, Benchmark, pictures and details ....

The maximum length of USB cable is generally 30 meters with hubs.  If you are over 30m underground, just use a repeater and come to the surface from time to time.  :- )
A 15 foot USB 2.0 is generally less than $3 and can replace a Coaxial cable without the loss. The Coaxial is also more expensive