Hi All,
I would like to extend the range of a home WiFi link (better signal strength down to the workshop) and wondered if anyone here had
*actually* built / tested one of those DIY 'can' type antenna / reflectors / whatever?What type of interface makes the job easier (USB 'dongle', remote usb 'compact type' , PCI / PCCard SMA connector etc)?
I guess something fairly directional would probably be best ..?
All the best ..
T i m
The illegal ones you mean ? :-)
Are they?
I thought it was 'ok' as long as you didn't exceed the max power into the thing?
So I take it it's the radiated power that is 'measured' and if so at what point around the antenna (ie if it's directional what is gained at the front will be lost at the side won't it?)
All the best ..
T i m
>
this any good
You need to look at some simple explanations of antenna theory. a directional antenna can have side lobes for instance.
Dave
Cool, a real DIY page, thanks! ;-)
T i m
If you don't have true line of sight, then you're shafted.
Even with line of sight, theses a thing called the fresnel zone which extends out in a cone from the direct line of sight. There are various calculations required to calculate this, but for most domestic appications, like of sight with a cylinder of a few metres diameter will give you a good signal.
Forget the USB ones - go for a pair of WiFi Bridges. Preferably ones designed for outdoor use with power over Ethernet. That way, you just plug one into the house LAN and the other into the workshop LAN.
I've built community broadband networks with various units - the favourite is the Smart Bridges range - they have various flat-plat directional units which are reasonably good in bridge mode, and more importantly, weather proof and take power over Ethernet. The ones we use are about
7" square.Power over Ethernet means that you just run one cable to the outdoor unit, and that cable is a digital data cable, rather than an analogue RF signal, which at the power levels avalable to you in WiFi applications is woefully weak and prone to cable, and connector losses.
You can built your own "pringle can" antennae and buy external antennae to fit onto some units, but then you have the problems of weather proofing it. You really do want the units outdoors pointing at each other, don't fool yourself with the advertising blurb that comes with them! You might get a signal through a wall if the antennae are prepindicular to it, but at an angle, pythagoras comes into play and the wall sudenly becomes a lot "thicker" that it might appear...
I have one link that 7.5Km long, and it's providing and acceptable signal for the home user, but they have a rather large grid parabolic reflector on the chimney of their house pointing back to the base station... So with care and the right kit, quite a lot is possible.
Saying all that, you might be lucky with ordinary kit - radio waves do reflect - but they will be severely attentuated by trees with leaves on
-I have some graphs that look great in the winter... Come spring when the sap starts to rise and you can see the signal strength drop )-:
Drop me an email if you want more details - it's actually been a while since I looked at the market and devices, but IIRC we were paying something like £150 each for the smartBridge units...
Gordon
Indeed, but I was just questioning if the 'rules' covered power to the antenna or radiated from it?
The problem I have had go like this ..
I have used a USB (V1.1) WiFi thingy (not 'dongle') on a 5m single port repeater and it's own 3m lead and that allowed me to position the remote end in a good place (good height / behind a window etc). Because of issues with the PC / USB I've made use of a PCI 11g card with antenna that attaches directly to the rear but the PC sheilds the RF to some degree. I could get one of those little remote stands to take the std 'rubber duck' (probably cheaper than buying a complete 'mushroom') but leads / connectors are all lossy and are sorta self defeating?
The (nearly) ultimate solution (outside of running cable) would be a Ethernet WiFi box (like an AP) but I don't have one and they aren't cheap? Also, it would need power and that may not be available near the optimum placement of the unit.
Maybe I'll go back down the USB route as it can easily be 'remoted', is host powered and the cables / units are pretty cheap now (I only need .11b)
All the best ..
T i m
With most things RF and goverment rules its radiated power that counts, that way it covers antennas with gain.... crafty blighters !!
Dave
I suppose a problem with that could be 'how' that signal is radiated and how 'close' to the upper tested limits the manufacturers sail?
ie, One make / model of WiFi kit is 'known' to work better (afa range lets say) than may others? Or have more options that may help propagation.
Ignoring the risk to humans from microwaves, I think what should be important to those who set the rules is what proportion of signal get's out past my boundries. Ie, if I lived in a Faraday cage I could (should be able to) use whatever power I like ;-)
So, if I want to get a signal down to my workshop I should be allowed to do whatever re the (max) power available (I'm talking antenna here) as long as the rf that actually makes it out of my house is below the permitted maximum?
I know the above is pretty unworkable in the real world but you get the idea ...
All the best ..
T i m
I sorta do Gordon. From the window in the spare (junk) room I can clearly 'see' the workshop.
Understood.
Ok ..
Is this 'legal' then Gordon. That panel seems likely to gave a gain greater than unity?
Like USB . didn't know you could get such but it makes sense.
rather than an analogue RF signal,
Indeed ;-(
Understood ;-)
Hmm, so if you were to 'reflect' (concentrate) the signal would that stay within the rules? What would be the practical difference then re using a Yagi?
All concrete here ;-) I *did* have a pretty reliable link using a Netgear AP to a Netgear USB unit (not dongle) but the AP seems to have died and a Belkin WiFi router has taken it's place for the moment running in AP mode.
Thanks for the kind offer ;-)
but IIRC we were paying
Ouch! A bit outside my league I'm afraid .. hence the 'DIY' interest ..
All the best ..
T i m
Thats why most things come with very ineffecient antennas and are ltd to low power. Even Faraday cages can leak!!
Dave
The fact is that if the RF doesn't escape from your property nobody is going to know about it, so what's the worry?
100 milliwatts ERP Effected Radiated Power. If you don't want to make a cantenna then this lot do some very good ones. We have a link in daily use that does 6.1 kilometres and its fine:))
"Effective" radiated power.
IOW, the power delivered to the antenna multiplied by the gain of the antenna, which in order to confuse, can either be measured relative to a dipole, or to a theoretical isotropic radiator.
The network I'm part of has many links of similar length or much longer, the longest is not far short of 20km. The longer hops use 24" dishes each end, the shorter ones long or short enclosed yagis depending on the distance.
The real key is line of sight and reasonable antenneas. Getting a signal down to a workshop shouldn't be a problem. I should imagine that you could get away with the stick on window patch jobbies at both ends assuming windows in suitable places near the PCs.
Chris Key
alignment done? Was it with a standard 802.11 access point at each end as well, or did it need something more serious?
What frequency does sKY TV satellite run at? If it's in the same ballpark as 802.11 I'd be inclined to try a USB dongle in place of the head elx (LNB?) of a sky disk to get a bit of directionality.
I bought a pair of 15dB gain antenna off eBay - cost about 30 quid the pair - the are external and very uni-directional and have SMA connectors at the end of about 2m of very nice coax - came from eastern europe. I have a Netgear WG602 combined bridge & WAP in my workshop and one in the house - about 100m apart with several brick walls between - the Netgear boxes say
65% signal strength when the aerials point exactly at each other. The ADSL gateway / NAT/Firewall/DHCP server is a Netgear DG834. I'm using 128bit WEP and dedicating the WG602 MAC addresses to each other to prevent people on the other side of the valley nicking my bandwidth ;-)Result - broadband on the whole 2 hectare site.
HTH,
Mike
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