Can the antenna length of a wireless router be increased to extend it’s wi-fi coverage? If yes , how? like say, a wire be used to increase it’s antenna length?
I read that placing a metal salad bowl behind the router would increase signal strength. Like a satellite dish does.
I forgot the description of the "longer" antenna - it always relates to the wavelength (which, for 2.4GHz Wifi is 12.5cm).
The most basic antenna types are the centre fed halfwave dipole (split at the centre for the feed line), or the end fed quarterwave.
Another popular arrangement, is the end fed 5/8 wave, the extra 1/8 easing the problem of feedin a dipole at the end, where the impedance is highest... why not a 3/4 wave? The extra quarter wave at the bottom operates in inverse to the halfwave above, and pushes the maximum sigan direction away from the horizontal, while the 1/8 is too small to have a difference.
To make a vertical longer, requires phasing arrangements to bring each half wave into phase with the next.
These can be quarter wave stub lines / delay sections, typically curved around the antenna or the "coaxial collinear".
The key point, any antenna has to tune to frequency (otherwise it won't operate efficiently in any direction) and direct the signal where required
http://www.instructables.com/id/DIY-WIFI-Antenna-Reception-Booster/ - not very well described, needs foil glued to the back, and the holes pierced so it fits over the antenna as a parabolic reflector.
A flat reflector would be metal or foil covered and placed 3cm (a quarter wave) behind the antenna - again, it would screen signal from the rear, but the increase in front signal would be less, but over a wider angle than the parabolic reflector.
http://users.picknowl.com.au/~gloaming_agnet/ant1.html - this shows a corner antenna, in this case, bringing the existing antenna away on a lead, but could also be constructed in a similar way to the cardboard & foil one.
All "gain" antennas work by redirecting signal from some directions to favour others, with the omnidirectional longer verticals achieving low angle gain by pancaking the pattern vertically (used with that style, a reflector should match the length of the antenna).
Other homemade types include the "cantenna" and grid antenna, while commercial directional antennas tend to of the Yagi type - either rods like a shrunken TV antenna, or loops.
Thanks for a sincere attempt to provide a practical solution to the query
The antenna is tuned to a frequency, so just "making it longer" would take it OFF TUNE and weaken the signal, or mess up the directionality.
The most basic antenna, the quarter wave, radiates and receives in all directions around (assuming vertical) and has a vertical directionality that is from mostly horizontal (actually best is a bit above) to about 45 degrees (not much goes up).
Moving to 5/8 wave, squashes the pattern lower toward the horizontal, but with antenna gain, there is no free lunch, gain in any direction means loss in another, and the reduction in upward signal may mean poorer upstairs coverage from a router that is downstairs.
A longer antenna ether needs additional complexity to bring all section in phase, or else the directional pattern will break up into lobes and nulls. The design of antennas is quite a science, and possibly the simplest way to change is to use some form of reflector, flat, corner or parabolic
Thanks for elaborate details. Please tell , how to increase coverage by reflector , flat , corner or parabolic?
Of course you realize that extending the range of your WiFi signal will also extend the range at which wardrivers can leech off of your signal?
Oron nailed that. You can't really use a longer antenna on the router to increase the range. If lengthening anything to increase the range, you would want to do that on the receiver end. You may have seen WiFi cards with removable flexible antennas. You can get 'larger' antennas that will attach to the WiFi card and make your reception better.
The parabolic mirror works much like a mirror behind a candle. It doesn't make for 'more' of a signal, it just focuses it in one direction.
I agree that custom-increasing wifi router antenna coverage is not practically reasonable
Probably not in the way you are looking for.
Of course (ab)using 1m of cable as an antenna will increase it's range but at the cost of signal quality and also transmit power. If the quality of the signal drops the network connection will drop frames and at some point render the connection useless. Also a lower transmit power will decrease the range from the "antenna" itself so the cable might cover an additional 1m but you probably lose the same or more in "over the air" distance.
To effectively increase the range you'll need a quality antenna with a higher gain than the current one. Of course this only works if your wireless device has a detachable antenna and you do have to look for the right RF connector (SMA, SMC, TNC, ...).
Also, when dealing with antennas you should inform yourself about their directional specifications.
On some occasions you might want to change an omni-directional antenna with a more directional one e.g. a Yagi antenna.
Last but not least you also have to know about wireless device. If it has more then one antenna one might be designated Rx (receiving side) and one Tx (transmitting side). In such a case you have to change both antenna equally.
Thanks. I understand the custom-increasing wifi router antenna coverage is not practically reasonable
In short, no. In theory you could do that, but you would need a router with a detachable aerial, and you would need to extend it to exactly the right length (half the wavelength of the carrier wave). If you have such a router though, you'd be much better buying a high-gain aerial for it.
Also, you can improve directional reception by using a parabolic mirror. There are instructions on the internet on how to use a small metal bucket for the purpose, or make such a mirror out of cardboard and aluminium foil!
Thanks. The parabolic mirror and the process illustrated in wikihow link by earlier respondent is same?
The one I had specifically in mind is http://www.freeantennas.com/projects/template/ . The idea is exactly the same - a parabolic "mirror" which will reflect the signal most effectively in one direction.
It's a well tested method. You can of course use a soda can too.
Thank you. I have opened and viewed the url provided in your reply