EEVblog Electronics Community Forum
General => General Technical Chat => Topic started by: Kiriakos-GR on December 07, 2011, 03:43:20 pm
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I am ready to get again one of those WiFi amplifiers, before two years I had got the first that was nice, but sold it again as soon I got my ADSL cable line.
Today I am again back to the wireless WiFi and I need to buy again one WiFi booster.
But I am a bit confused mostly about the performance gain between the one called as 1W ( That I have experience),
with the 2W version, that is the same item with 2db more gain in the transmission, that is 30dbm VS 33dbm.
And the last months it looks to be and another model out there from another manufacturer in Taiwan? ( or they say so)
That was another shape but similar base features.
Did any one actually know or did any comparison between those latest 2W models ?
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For what purpose do you need a booster? Most places in EU are limited to very very low output wattage - but I do not know about greece. (Unless you have a license)
Most amplifiers will kick everything else off in the vicinity - so if you broadcast on ch6 - you might kick everyone within 300m off if they are anywhere close (chn 4-8) - since they are on 0.1 watt.
If it is a point to multipoint link (like a normal accesspoint) increasing transmit power to 2watt will not do you any favours since the clients can't send at the same high power. So you might see the accesspoint from further away but using it is "a challenge" - since receiver sensitivity usually gets quite "busted" by the amplifier.
If it is for a point to point solution - use the right equipment like ubnt.com stuff for a low cost solution.
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A power boost on only one end might make sense if you need high bandwidth in only one direction. It will allow your router to send at a higher speed, even though your clients are still going to send at a limited speed. It is correct, however, that those amplifiers are mostly useful for point to point links.
If you're trying to connect to a wireless ISP, try a better antenna first. It's very easy to build one from a tin can. Mount it on an old satellite dish for even higher gain. Put your adapter as close to the antenna as possible.
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I once tested a WiFi over ~ 3km using a old 60cm satellite dish and a backfire antenna to feed the HF into the dish. No HF amplifiers were used.
Easier solution would be to take a USB WiFi 'dongle' and put that in the dish's LNB holder.
Stay away from HF power amps, they are a total disaster given that they f* everybodies WiFi coverage in the neighbourhood.
100mW EIRP is probably the limit in Greece too, so it would be illegal as well.
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The power limit in Greece is 100 mW (anything else requires special licensing). A real 2000 mW transmitter with an omni directional antenna would kill everything wi-fi related in the same channel in a large radius.
The best way to go with it is a panel antenna or directional antenna+feeder.
Another famous solution is the known 500/800/1000 mW Alfa usb cards (with the same issues of high power transition).
(http://i.imgur.com/TuRxj.jpg)
Alexander.
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Interestingly enough, we get over 2Kms of range using a 100mW ERP with our RC model aircraft.
Power is only one factor when it comes to increasing the range of an RF link and often, it's the last resort. Often, much better returns are to be had by improving the RF link, antenna positioning and other factors first.
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Interestingly enough, we get over 2Kms of range using a 100mW ERP with our RC model aircraft.
Power is only one factor when it comes to increasing the range of an RF link and often, it's the last resort. Often, much better returns are to be had by improving the RF link, antenna positioning and other factors first.
Very true. Keep in mind your RC kit is using 27 MHz or 48 (?) MHz. Which has very different characteristics than the 2.4GHz of WiFi.
I run a dual-band radio equipped WiFi AP, with one radio at 2.4Ghz, the other on 5GHz. 5GHz is nice and fast, and given it is far less used, it has much less interference from other WiFi users. At 5GHz propagation through brick / concrete walls etc is just magnitudes worse than on 2.4GHz. Probably also due to reflections.
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With 100 mWatts a big parabolic antenna and a feeder you can "easily" exceed 20 Km with very good speed.
Alexander.
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People thanks for the legalities, but my question are very specific.
I do have ultra directional antenna YAGI 30 elements , and 3COM bridge from the ones that cost as 200EUR.
Even so I have to pass inside from few walls.
The conditions are a bit problematic.
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Interestingly enough, we get over 2Kms of range using a 100mW ERP with our RC model aircraft.
Power is only one factor when it comes to increasing the range of an RF link and often, it's the last resort. Often, much better returns are to be had by improving the RF link, antenna positioning and other factors first.
Very true. Keep in mind your RC kit is using 27 MHz or 48 (?) MHz. Which has very different characteristics than the 2.4GHz of WiFi.
No, I'm talking about FHSS 2.4GHz RC systems.
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I dont know exactly your need but when building my house a construction supervisor (my father) installed too much of iron support and in this house cell phones and wifi does not work. I ended on a 5 W amplifier and could not get wifi to work in next room. Then i bought powerline and solved my problem, maybe it can help you too.
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My link is over 1 Km distance.
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My link is over 1 Km distance.
Oh well, that is another situation. Still there is a solution of router accepting with data sim card slot, those tarifs are really cheap
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My link is over 1 Km distance.
my recommendation is still get a couple of Ubnt boxes with directional antennas if you have line of sight. If you boost to 2watt and you are allowed only .1 watt you WILL get into trouble if just one of your neighbours have any Wifi knowledge.
And remember the 100mw is from ANTENNA out - not what the box is set for. So if you use a high gain antenna plus amplifier plus short antenna cables - your real output might end up in the 3-4 watt range.
And.. remember the LOWER the Frequency the better "wall penetration" you will get. 5GHz have very little through wall penetration where 2.4GHz is better and 900 Mhz is even better. :-) If the 900MHz frequencies are allowed in Greece that was what I would do for a 1km link. On top of that you will have to experiment with ACP settings to optimize them to a 1KM link.
If you want to get the best speed - then back to my original suggestion. They RocketMGPS from UBNT. They use GPS to set the ACK settings to get a "true" TDMA signal (Time Division - so each device knows when it can transmit and they don't try to talk at the same time) 1KM links without TDMA will get issues from time to time due to ACK settings. Home wifi routers are not made for more than about 150feet so their AutoACK algorithms will quite often NOT work well on longer distance.
High speed "bridge" http://ubnt.com/rocketmgps (http://ubnt.com/rocketmgps)
Most of the UBNT products are outdoor and "damn" cheap compared to the competition. The rocket without GPS have some TDMA but not perfect like the GPS version.
Alternative is MikroTik routers with their NV wireless. Cheaper but requires the big Mikrotik Book of Mumbo Jumbo to get working :-)
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If you have line of sight and control of both ends, laser or focused IR LEDs is an attractive option. Then again, if you have control of both ends, an amplifier (if needed) and directional antenna on both ends would also be a great idea.
my recommendation is still get a couple of Ubnt boxes with directional antennas if you have line of sight. If you boost to 2watt and you are allowed only .1 watt you WILL get into trouble if just one of your neighbours have any Wifi knowledge.
What about take the signal from the adapter and split it to an array of antennas (each with its own amplifier) such that each unit is less than the limit but phased to combine to the equivalent of one very high power unit? (Such a system would be very difficult to phase properly, so probably not a good solution. But some of the new routers already do it with 2 or 3 transceivers in one band.)
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The directional WiFi is a beam with 6 meters diameter.
The ones who speak about interference to near by networks, they do not have a clue of what they talk about.
Even so, I just ordered and payed about the modern version of the True Taiwanese version.
Picture No2 at my first message.
As trusty and reliable due the successful 1W version that I was had before.
The fact that this one have dual LED, its the proof that it is a truly later made version,
and probably the freshest made by this specific manufacturer.
Thanks for all the advices, please consider this topic as ended.
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The directional WiFi is a beam with 6 meters diameter.
The ones who speak about interference to near by networks, they do not have a clue of what they talk about.
Even so, I just ordered and payed about the modern version of the True Taiwanese version.
Picture No2 at my first message.
As trusty and reliable due the successful 1W version that I was had before.
The fact that this one have dual LED, its the proof that it is a truly later made version,
and probably the freshest made by this specific manufacturer.
Thanks for all the advices, please consider this topic as ended.
The frenel is actually, with a 100% directional antenna, 3.3 meters @ 5m height in both ends with a 1km link. But shooting into a wall the signal is no longer directional - and no antenna is 100% directional. But I am sorry you feel offended.
But if you have a great Yagi - they have a beamwidth of 30deg (-3db point) - that means your signal at 1KM away is actually just a tad more than 500 meter wide not taking reflections into account.
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There is nothing to do about feel offended. :)
My nerves system have all ready collapse, when I am between 10 & 15% signal, and I need stable 15%, so to have a packets transfer.
Its a true torture to need 2-3% more signal , and every microwave oven or dust or humidity to effect it,
by a negative way.
This little booster is my last hope.
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I looked at different homebrew Yagi's last night and was able to find some between 27 and 100 element - but with "little" documentation. Which Yagi do you have?
The 27 Element I found had a gain of 16db and beamwidth of 16 degrees. 16 degrees gives a 286 meter wide beam @ 1km. But the more directional usually the greater the bloom around the base.
Here is the beamwidth formular for excel =tan(radians(#beamwidthInDeg))*#length - returns width in the same definition as #length (so m=m, f=f)
Anyway - if you want to try to get legal :-) the Greek distributor of Ubiquti is
http://aerial.net/shop/ (http://aerial.net/shop/) - I think if you with 3com wireless bridge are close to having a signal - just putting in a Rocket as replacement would bring you there without extra amplification.
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For your eyes only ;D
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I wonder how your antenna would compare to a tin-can waveguide like this? http://www.turnpoint.net/wireless/cantennahowto.html (http://www.turnpoint.net/wireless/cantennahowto.html)
(http://www.turnpoint.net/wireless/images/nalleyscantennabig.jpg)
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Yagi Udo's usually work much better than CANtennas.
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For your eyes only ;D
thats an advanced antenna... extended elements, combat shaped parabola, and 2 axis direction adjustment! i believe you were k1r14k05! :D
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For your eyes only ;D
thats an advanced antenna... extended elements, combat shaped parabola, and 2 axis direction adjustment! i believe you were k1r14k05! :D
12 Years experience with FM - VHF - CB, is always gain. :)
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I did some noise on the ebay seller so to use fast shipping, and after of some sort of ping-pong with messages he agreed,
the lady who answers the messages she said that the factory will be closed for the weekend and that they will ship Monday.
The word factory .. it did some impression to me, because actually its true, those wholesalers with the 10.000 sales per year,
its an organized factory with lots souls as engine.
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with lots souls as engine
there's the problem they cannot get 100% rating. miscommunication between receptionist and packing man will result wrong item being sent. hope it will not happen to you :P
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12 Years experience with FM - VHF - CB, is always gain. :)
VHF is very different from microwave.... have you tried it without the dish?? did you tune it after adding the dish? that antenna already has a reflector... (the final element) i have a feeling that dish is pumping the side lobes somewhere they shouldn't be going.
you should have no problem getting a reliable 1km point to point link with a pair of yagis & decent unamplified routers .
-sj (wd4awb)
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have you tried it without the dish??
The dish works as shield from the 30 routers at my back, and 10 routers at my side.
And so I have just 20 routers at the front.
Multiply all those sources as noise, and you will find out why I have come to this solution.
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will result wrong item being sent. hope it will not happen to you :P
Nahh Nina loves me very much so to let this happen. :P