Range limiting factor: the reciever antenna?

[adaweawe]

Hey guys, I've read a lot of information about improving the home wifi wireless range of the router by installing high gain antennas or adding reflectors, etc. But if the receiving device, for example a laptop, also has to send upload data (which is always the case, since the laptop also has to send various signals to the router), doesn't that mean that the Wi-Fi range is limited by the antenna on the laptop?

But I guess maybe this isn't the case, since In a similar example on a cell phone the tiny antenna is able to send signals all the way to the towers. I'm not really sure how all this works, but I'm very detail oriented so I was wondering about this issue.

ok just found this: http://forums.whirlpool.net.au/archive/2007106

 

[TonyH]

Hi,
When talking about hi gain antenna reflector and directors are part of structure. Cell phone cell site has huge tower with higher TX power and
proper antenna arrays to cover the area. RF LOS is different from optical
LOS. There are endless factors affecting RF signal in any environment.
The higher the gain on antenna the more it becomes directional. Even weather and soil condition, affect the signal, etc. Signal polarization matters too between TX & RX antenna. RF signal has two element E and M.
Energy is in the E.

 

[stevech]

Hey guys, I've read a lot of information about improving the home wifi wireless range of the router by installing high gain antennas or adding reflectors, etc. But if the receiving device, for example a laptop, also has to send upload data (which is always the case, since the laptop also has to send various signals to the router), doesn't that mean that the Wi-Fi range is limited by the antenna on the laptop?

But I guess maybe this isn't the case, since In a similar example on a cell phone the tiny antenna is able to send signals all the way to the towers. I'm not really sure how all this works, but I'm very detail oriented so I was wondering about this issue.

ok just found this: http://forums.whirlpool.net.au/archive/2007106

Improved antenna gain on either end of a link benefits both directions. That is, gain is "reciprocal". Increased transmitter power benefits only one direction and causes an imbalanced link.

The reflectors and so on, homebrew, are largely sillyness. A reflector has to be parabolic and have the right kind of antenna at the focus, much like sunlight in a solar collector. A partial parabolic (like the commonly used wire-grid BBQ-grill antennas) is fine too, it just sacrifices a bit of gain for a smaller antenna - but it's still parabolic. Yagi type antennas get their gain by having director elements that are sized and spaced to a specific frequency band. Omni-directional antennas get their gain by stacking dipoles in a mathematical relationship, e.g., you'll see that a 2.4GHz 12dBi gain omni is about 30 inches long. A lot of marketeers claim gain which are simply falsehoods.

As gain gets up above 10 or more Db, you have directionality to "fight". Maybe you don't care as it's a point to point bridge link. More often, you do care. A high gain omni has a 360 deg. horizontal pattern but a narrow (say, 10 degrees) vertical pattern - like a doughnut. Elevate that omni very much and you have a weak signal situation below and close to the antenna.

Coverage is best improved in WiFi with either real engineered gain antenna connected by a 1ft. coax of the right kind, to a WiFi device that does not use MIMO.

In modern MIMO WiFi routers, the way to improve coverage is not to screw around with smoke-and-mirror antenna hacks, but rather, to simply add access point(s).

 

[TonyH]

Hi,
The thing is matching the load(antenna) to TX. Otherwise it's all for naught.
Reflector does not have to be solid material. As long as the mesh size is less than 1/20th of Lambda, it is considered OK. Also it lessens the wind load. Biggest antenna I worked on was 120x120 foot parabolic fed by wave guides on tri-diversity. Reflector was like a fine metal screen. This after market WiFi antennas all mention gain figures but I don't see any radiation pattern graph, typical SWR figure being mentioned. El cheapo antenna may make things worse even damaging equipment.

 

[stevech]

Yes.
There are too many articles on line showing people putting random sized/placed tin foil, potato mashers, salad bowls, magic material, long coax, and so on. But it is humorous.

 

[sfx2000]

Hehe...

One can always tinker - basically, WiFi has a link budget (RF energy from the Access Point to the Client).

Throwing a lot of power at the AP is like screaming into the wind - makes a lot of noise, but doesn't do much.

Put more emphasis on the clients - that is one of the top two secrets of WiFi performance

sfx

 

[stevech]

Hehe...

One can always tinker - basically, WiFi has a link budget (RF energy from the Access Point to the Client).

Throwing a lot of power at the AP is like screaming into the wind - makes a lot of noise, but doesn't do much.

Put more emphasis on the clients - that is one of the top two secrets of WiFi performance

sfx

Since WiFi is bi-directional, the transmitted power from-client is equally as important as the transmitted power to-client (from WiFi router/AP).

All clients display the received signal strength.
Few WiFi routers/APs list the received signal strength (from client).
So people tend to look only at the to-client signal.
A hundred-watt WiFi router/AP won't improve things, since the client device remains what they are: about 0.03 watt (30mW) in fast data rates, up to 100mW in slow data rates. Vendors don't tell you this.

 

[sfx2000]

LOL - remember the days of CB... 100W/1000W/MOOAARRR! Linear Amplifiers - listening to AM radio with "Breaker, breaker One Nine good buddy!" - toss in some reverb for the really big voice!

As to WiFi - more power - cool to read my twitter feeds on my morning toast!

Time to get in the shed and start tinkering - perhaps I can put out an ASUS build that really, really powers up their routers, then Netgear can be mega-pissed

Or perhaps DD-WRT and let my old WRT-54G fry bacon...

I can see the SSID now - "blowtorch b**ches"

(just kidding, don't take me seriously please)

sfx