Boost Wifi Signal Range.

[thai4u]

I searched in google and others and have so many tricks suck as connect a mobile phone to the router to increase the signal range+dish of aluminium paper..

I search for a ready product that I will connect to the router and thats all.

the situation today is that when I even go to the second floor (building) so have signal but much less strong(my laptop show "low signal").

I want not only to be able to connect with good signal from second floor but from the third floor AND the area of my house about 500M (n,s,e,w)around me.

any ideas? have to be economic solution not expensive but efficient.

THANK YOU

[Guest Reimar]

I searched in google and others and have so many tricks suck as connect a mobile phone to the router to increase the signal range+dish of aluminium paper..

I search for a ready product that I will connect to the router and thats all.

the situation today is that when I even go to the second floor (building) so have signal but much less strong(my laptop show "low signal").

I want not only to be able to connect with good signal from second floor but from the third floor AND the area of my house about 500M (n,s,e,w)around me.

any ideas? have to be economic solution not expensive but efficient.

THANK YOU

Just use an antenna with 10 or more dB. I use an outdoor antenna with 16 dB and have a range from 200-300 m! Cost of this antenna was THB 4,500! Not cheap but usefull! An 8 or 10 dB antenneacost THB 2,000 - 3,000!

[Prasert]

"economic, not expensive but efficient"

Getting a good signal comes down to the following:

- the antenna used

- the coaxial cable used

- the connectors on the coaxial cable

RG58 is a very cheap coaxial cable one can use for WiFi but performs very poor when the cable length is 1 meter or longer.

TV coaxial cable is useless.

Antenna's you can buy in Pantip Plaza - a 12dBi omni directional antenna will be about 40cm long. Most external antennas have a female N-connector. Reasonable priced coaxial cable and proper connectors can be bought in Ban Mo (the "electric area" next to Old Siam). RG200 coaxial cable looks the same as RG58 but performs almost as good as Aircom cable.

[technocracy]

Just increasing the antenna power isn't the solution here! The more you increase the antenna power the more focus the signals become even with omni direction antennas - the signal spread becomes more of a ring doughnut shape. So if you are close to the antenna you would get poorer levels however then moving away from it puts you into the better signal band.

Also signals do not travel upwards - unless you direct them upwards - being radio waves they generally travel in straight lines.

The other thing you need to consider is the density of the walls and floors in you house - since radiowaves don't penetrate all to well. The typical Thai house that has a concrete rendered walls is pretty much a wireless nightmare! Sure the signals will bounce, scatter and refract there way around your house to certain parts (via windows and glass etc) but in general concrete absorbs the waves.

My house out of curiousity I tested a wireless connection in my house and due to the construction from the office to the lounge (8 metres there abouts) you can only just receive a signal - that was if I left the 2 doors between the lounge and office open, close them and the signal went. All very normal.

For the kind of setup you want it's not going to be that easy - inside the house between rooms I'd probably use PowerLine adaptors these are nift little gadgets that plug into your power sockets in the house. They then use the power cables as there network - the one you plug in next to your router will most likely use a Ethernet connection then the rest around your house are wireless antennas. So you can then plug them in the upper floors of your house.

Your 500m spread around the house would best be attempted by using a high powered omni antennas installed at the highest point of your house outside. The actual gain of the antenna (dBI) will be dependant on the power output of your router. However there is no guarantee of success since the distance is dependant on your PC antenna. In general the inbuilt 802.11b/g adaptors on notebooks don't particualrly have very good send and receive levels. In comparison to a PCI card with an external antenna that is - which aren't hugely better but are an improvement.

Edit: The 500m spread just to add in any commercial operation would NEVER be attempted with a single antenna - a 1km radius from a single antenna is very unlikely to provide reliable connections, as mentioned your Laptop won't beable to connect beyond a certain range anyway regardless of the central antennas power. In a perfect world you would really need 3 most likely 4 patch antennas with APs to give well controlled coverage of this area.

No simple answer I am afraid - all wireless networks are dependant on the surroundings and need to be designed as such to give optimum performance.

Edited October 15, 2007 by technocracy

[thai4u]

technocracy. thank you very much for your answer . you really game me a lot of details and get the idea of establish a wireless service and better connection.

If I understand what you said is that if I really want a 500M range of wireless connection I need to install 4 omni antenas? one more thing that I didnt understand is what db do I need for this thing? is 8/12/15 will be enough?

I saw a compaq omni 12 db for 4000 baht in some website.

the gadget you mentioned..where to be found do you have any link to give me a clue what to search for ?

[sinom]

I have a large two storey house. I use a Zyxel router upstairs in the office and carry round an extender when I want to use another laptop downstairs.

I use the Linksys WRE54G extender, simple but effective.

Check out the linksys.com website under routers and extenders

cheers

[cloudhopper]

We are experimenting with a neighborhood wifi system having 500+ meter links using trough reflectors. A commercial hygain outdoor omni antenna is mounted (about 2.5" away using the supplied mount) to a sheet metal (1.5mm galvanized steel) reflector bent up 45 deg along a line 5" out each side from the center line (above which the antenna is mounted). Remaining dimensions not critical. Probably around 10+ dB gain for 30"H X 50"W. Cheap gain over a 90+ deg azimuth.

[Guest Reimar]

As I don't want to critisize what others wrote from their experiences, I would certify that I'm able to use my WiFi system stable (2 level points) within a range of 180m from my office with an 16+ dB Outdoor antenna, mounted on the top of the roof of the house and connected to the router with RG200.

If I use my laptop with builtin WiFi 54 Mbps I could use the the Laptop with a minimum of 2 lavel points within 180 m from my hous and in all rooms in the house as well. The min distance to the antenne is at all times 5 m +!

Thart means I've an arial diameter from 360m to use the WiFi with sure ans stable connectoion!

technocracy

Edit: The 500m spread just to add in any commercial operation would NEVER be attempted with a single antenna - a 1km radius from a single antenna is very unlikely to provide reliable connections

A radius of 1 km is an arial diameter of 2 km!! As far as I know, the measure of Radius is from the center to the Outline and not a diameter!

So 200-300 m distance is an max of 600 m Diameter but a max of 300 m Radius!

[elkangorito]

Interesting comments.

I use a "standard" AP to interact with my wireless host, which is about 300m to 400m away. The Host I use is another AP. Reasonable signal with good reliability.

Don't forget that antenna input gain is higher than output gain & also (based on an isotropic radiator), the power output of a transmitter will determine how well the signal can be received.

If I could interact with the main AP host (I can't due to hardware compatability problems, I think), my rx (receiving) signal strength would be fantastic because the main transmitter has a higher power output than an AP, its antenna & my antenna are both vertically polarised & the main host antenna is about 4 or 6 wavelengths long (a visual guess). Also, I have "line of sight".

[Veazer]

When using external antennas, be sure to test with the antenna directly attached vs. using the included cable. Microwave frequencies do not travel down wires very well and the cheap cables included are usually very lossy.

NetStumbler is a great tool for assessing signal strength, i recommend giving it a try for your testing.

[elkangorito]

Just curious...does anybody here know about coaxial cable losses, isotropic radiators, VSWR & antennas in general?

[Prasert]

Just curious...does anybody here know about coaxial cable losses, isotropic radiators, VSWR & antennas in general?

Yes, I do

....but not at the moment, just got home after a night drinking on the beach.

I've got some accesspoints running, covering several areas so ask away.

[nikster]

The easiest solution to cover your home is to use WiFi extender boxes, all from the same manufacturer.

A wireless-N router will work a whole lot better in a house as well but you need a wireless N card in your laptop or an external USB wireless-N card.

500m around the house would be an extremely large area to cover. You'd be covering a whole city block. Are you sure you really need 500m?

[cloudhopper]

"Don't forget that antenna input gain is higher than output gain"

What is meant by this nonsensical statement? A classic theorem in antenna engineering is that any antenna has reciprocal characteristics transmitting or receiving.

[ianc66]

I have more or less done what the OP is asking for at near zero cost. Introducing the Wifi-Signal-Strainer-WokFi

I live on an out of town estate of about 20 Rai with 12 large houses, and use IPStar -- better than it was -- as the backhaul.

The IPStar dish is mounted at the base of the water tower (height about 15 Meters) at the top of the water tower is a completely standard LINKSYS AP. UPS power and a ethernet cable run up the tower. Linksys router in a fat trap relatively weather and water proof. Access is shared. A neighbour about 100m away gets good access just with his laptop Wifi. I am rather further away at the wrong side of my house through three thick 25cm walls -- yes really and it works using this

http://www.instructables.com/id/Wifi-Signal-Strainer-WokFi/

This solution has been working faultlessly for 21 Months. When I first built my Wifi signal strainer I took it for a walk with a laptop good signal at 500 mtr+ from the water tower.

[technocracy]

Just curious...does anybody here know about coaxial cable losses, isotropic radiators, VSWR & antennas in general?

Yes thanks. I even have professional certifications also along with experience of designing and installing dozens of commercial wireless networks (supporting hundreds of users) and have worked with 802.11 since products came to the market around 1996-7 (if remember rightly).

Sorry previously I meant diameter not radius (for some reason I always confuse the two!)

So lets go through the facts and figures:

As the example given is a 16dbi antenna attached to a standard router - lets just say for arguements sakes it's connected to a router which has a power output of 18dBm (average range).

You have an 18dBm (63mW) signal which given say a 5dB loss for cable and connectors (rough estimate - based on RG200 - 5 metres) plus 16dbi gain of the antenna - has an EIRP of +29dBm (794mW).

Your average Laptop has a 2dBi antenna with a max output of around 17dBm - with say -3db lost at the connector - has an EIRP of +16dBm (39.8mW).

The average sensitivity for an integrated laptop cards at 54meg is -72dbm and around -85dbm at 11meg.

The Free Space loss for 300m is -93.75dBm, 500m -93.98dBm loss, 1km -100dBm, 2km - 106.02, 3km - 109.5, 6km - 115.5. Above 3km the Fresnel Zone and the curvature of earth start to come into play - and I don't think its need it here.

This means for when you are 300m away from the antenna -93.75 + 29 = -64.75dBm, your 16dBi antenna is blasting out even over a 6km diameter -86.5dBm. So someone 3 kms away with a similar setup to you could connect to your network.

In purely theoretical terms in perfect conditions a Laptop can connect over 1km since Free Space Loss over 1km is -100dB (so still receiving -81dBm over 1km). However theory and reality are two very different things when you take into account the environment and surroundings. Like Ianc says things are perfectly possible even using a standard 5dBi antenna supplied on the AP.

But anyways like I said before try it and it might work, but lets be clear about my comments about a commercial environment and reliable connections. I am talking about buildings that have been surveyed from top to bottom for all black spots and full speed connectivity is available regardless where someone is in the building - also we aren't just talking about 1 or may be 2 users I am talking about several hundred.

The idea of just installing the most powerful antenna they can find to provide coverage would NEVER be done in a commerical environment. Not only due to mW levels, there is no control on the spread of signals (read: security) and no control of black spots.

But anyway this isn't commerical that was just an example, personally I try mounting the standard 5dBi antenna up in the loft space or outside first and see what coverage it provides before going and buying any high gain antennas.

[elkangorito]

Finally!!!!.....someone who can talk "antennas" .

If I get the time one day (yeah, right!), I might be silly & construct a multiple wavelength log-periodic...just for the (h)ell of it! It could be interesting to get some "DX" wireless stations .

[Thanh-BKK]

Hi

I also have some knowledge about antennas, yet this is limited to much lower frequencies - namely 27 MHz where i used home-built antennas for worldwide DX (yes that's ordinary CB radio).

One well-known trick amongs CBer's is to use an (illegal of course) "afterburner", which in simple terms is a RF amplifier. Say the CB rig puts out 4 watts, instead of going to the antenna one will feed these 4 watts into an "afterburner" which in turn send 500 watts to the antenna.

Now isn't there similar devices available for WiFI uses? I understand the frequency is what - 2.4 GHz? Such frequency doesn't like any solid matter between it's sender and it's receiver (the lower the frequency, the better it travels thru such obstacles, which is why Hutch phones (800 MHz) have signal in basements where D-TAC (1.800 MHz) won't reach).

Now these WiFI devices emit a few milliwatts only - which doesn't exactly help the signal to travel far. Why not just use an "afterburner" there too? I think even an ordinary 1/4 wave vertical antenna, if fed with 1 watt of RF, would have a greater range than any expensive 16db Yagi-type directional antenna which is fed with a few milliwatts.

Then what's that with the dB's anyway? A vertical (omni-directional) antenna can't have too much gain - you get gain by directing the signal into one direction, and the narrower you bundle it, the higher your gain (the more passive "director" elements the antenna has, the narrower the signal, hence the higher the gain). But an ordinary vertical? They can be 1/4 wave (ideally with ground plane or "tripod"), 1/2 wave (ideally a Dipole), 5/8 wave (involves Radials) or 7/8 wave (which involves radials, too). I don't think that stacked antennas are available for WiFI, are they? They would have a certain gain over Dipole (dBd) too.

All other verticals only have "gain over Isotropic Radiator", dbi. Which is basically marketing gimmicks - as an isotropic radiator does not practically exist, it is a theoretical thing which would send a radio signal equally to any direction of a hemisphere. Which not even the simplest of "real antennas", the 1/4 wave, does - and hence even this simplest of antennas already has a certain gain over Isotropical radiator (dbi).

But back to the thing - are "afterburners" for WiFI available? Are they legal? They would be the best thing to use.

Best regards....

Thanh

[onethailand]

I have more or less done what the OP is asking for at near zero cost. Introducing the Wifi-Signal-Strainer-WokFi

Nice one - classic! Bit OT but you think that might work for cellphone signals as well? Or anyone have any suggestions how to improve reception?

[Prasert]

Hi

I also have some knowledge about antennas, yet this is limited to much lower frequencies - namely 27 MHz where i used home-built antennas for worldwide DX (yes that's ordinary CB radio).

One well-known trick amongs CBer's is to use an (illegal of course) "afterburner", which in simple terms is a RF amplifier. Say the CB rig puts out 4 watts, instead of going to the antenna one will feed these 4 watts into an "afterburner" which in turn send 500 watts to the antenna.

Now isn't there similar devices available for WiFI uses? I understand the frequency is what - 2.4 GHz? Such frequency doesn't like any solid matter between it's sender and it's receiver (the lower the frequency, the better it travels thru such obstacles, which is why Hutch phones (800 MHz) have signal in basements where D-TAC (1.800 MHz) won't reach).

Now these WiFI devices emit a few milliwatts only - which doesn't exactly help the signal to travel far. Why not just use an "afterburner" there too? I think even an ordinary 1/4 wave vertical antenna, if fed with 1 watt of RF, would have a greater range than any expensive 16db Yagi-type directional antenna which is fed with a few milliwatts.

Then what's that with the dB's anyway? A vertical (omni-directional) antenna can't have too much gain - you get gain by directing the signal into one direction, and the narrower you bundle it, the higher your gain (the more passive "director" elements the antenna has, the narrower the signal, hence the higher the gain). But an ordinary vertical? They can be 1/4 wave (ideally with ground plane or "tripod"), 1/2 wave (ideally a Dipole), 5/8 wave (involves Radials) or 7/8 wave (which involves radials, too). I don't think that stacked antennas are available for WiFI, are they? They would have a certain gain over Dipole (dBd) too.

All other verticals only have "gain over Isotropic Radiator", dbi. Which is basically marketing gimmicks - as an isotropic radiator does not practically exist, it is a theoretical thing which would send a radio signal equally to any direction of a hemisphere. Which not even the simplest of "real antennas", the 1/4 wave, does - and hence even this simplest of antennas already has a certain gain over Isotropical radiator (dbi).

But back to the thing - are "afterburners" for WiFI available? Are they legal? They would be the best thing to use.

Best regards....

Thanh

Basically the story for WiFi (2.4GHz) is the same. It's just a matter of recalculating the antenna elements sizes.

However the story is different when it comes to transmit power and boosting the transmit power. The best comparison can be made with a mobile phone: tiny antenna and not much transmission power. The same goes for an accesspoint: attaching an external antenna will give you a stronger signal, but also a higher sensitivity!

Using a booster (e.g. afterburner) will expand your range. A laptop will be able to receive the signal much further away, but it won't be able to transmit a signal back.

Another big difference is the SNR. When you're talking to someone on 27MC, it's easy to understand what is being said, even when there's a lot of static or small drops in the transmission. So one could say the SNR is high.

WiFi on the other hand, transmits a lot more data at the same time requiring a 'clean' line and enough bandwidth in the radio spectrum to transmit the amount of data.

2.4GHz seems to be a poor choice when it comes to penetration, but that's just the way it is.

I'm now experimenting with WiFi on 915MHz, using the 20MHz band that is available between the GSM frequencies used on the masts and the mobile phones. Works nice, but the antenna's are very large.

[technocracy]

Hi

I also have some knowledge about antennas, yet this is limited to much lower frequencies - namely 27 MHz where i used home-built antennas for worldwide DX (yes that's ordinary CB radio).

One well-known trick amongs CBer's is to use an (illegal of course) "afterburner", which in simple terms is a RF amplifier. Say the CB rig puts out 4 watts, instead of going to the antenna one will feed these 4 watts into an "afterburner" which in turn send 500 watts to the antenna.

Now isn't there similar devices available for WiFI uses? I understand the frequency is what - 2.4 GHz? Such frequency doesn't like any solid matter between it's sender and it's receiver (the lower the frequency, the better it travels thru such obstacles, which is why Hutch phones (800 MHz) have signal in basements where D-TAC (1.800 MHz) won't reach).

No there isn't such things - depending on which part of the world you are in - is dependant on what the mW/W limits are. FCC and IEEE have differing opinions of what is safe! Which is important since at these higher frequencies of microwave you could be beaming out very harmful waves at high power - look at what a 2.45Ghz 500 watt microwave oven does to food - imagine your head in line with that antenna! It's just the way of the world that the higher frequencies are absorbed more in inanimate objects (which is obviously even worse for 5.8Ghz 802.11a).

Now these WiFI devices emit a few milliwatts only - which doesn't exactly help the signal to travel far. Why not just use an "afterburner" there too? I think even an ordinary 1/4 wave vertical antenna, if fed with 1 watt of RF, would have a greater range than any expensive 16db Yagi-type directional antenna which is fed with a few milliwatts.

Then what's that with the dB's anyway? A vertical (omni-directional) antenna can't have too much gain - you get gain by directing the signal into one direction, and the narrower you bundle it, the higher your gain (the more passive "director" elements the antenna has, the narrower the signal, hence the higher the gain). But an ordinary vertical? They can be 1/4 wave (ideally with ground plane or "tripod"), 1/2 wave (ideally a Dipole), 5/8 wave (involves Radials) or 7/8 wave (which involves radials, too). I don't think that stacked antennas are available for WiFI, are they? They would have a certain gain over Dipole (dBd) too.

Exactly. Many people don't understand that virtually all 'omnidirectional' antennas are dipoles - so when they use high dBi antennas they focus the spread in two directions rather than circular omni direction. I do not know of any stacked antennas for wifi. Again they pretty much all fall foul of the mW limits imposed.

All other verticals only have "gain over Isotropic Radiator", dbi. Which is basically marketing gimmicks - as an isotropic radiator does not practically exist, it is a theoretical thing which would send a radio signal equally to any direction of a hemisphere. Which not even the simplest of "real antennas", the 1/4 wave, does - and hence even this simplest of antennas already has a certain gain over Isotropical radiator (dbi).

But back to the thing - are "afterburners" for WiFI available? Are they legal? They would be the best thing to use.

Best regards....

Thanh

As above no and no they aren't legal.

[stevenjm]

For boosting signal strength and sticking to a budget you might want to consider a good ground plane for your router.