Is there a inexpensive ways to increase wifi range indoors ?
Is there a inexpensive ways to increase wifi range indoors ?
That's probably the right way to improve the range.
However, I now have a way to make the Wi-Fi signal go around corners and through floors. Waveguide, as 4" dia aluminum dryer vent hose: |
Now that's something completely different. In the same spirit, I was wondering if I painted two adjacent walls with conductive paint (isn't there something like paint with metal particles in it?) and then put regular paint over it to hide it, could I place a radio near the intersection of the walls and create a huge corner reflector?
Re my possibly ridiculous post about a room sized reflector:
Jeff, have you ever modeled a corner reflector with sides of, say, 12 feet by 12 feet fed by a rubber duck type omni antenna? What program do you use for modeling?
Corner reflectors don't scale very well beyond perhaps 1 or 2 wavelenths per side. The nice smooth front lobe pattern starts looking like a "fan like" series of small lobes. You're much better off with a parabola with large reflectors. Also, the gain doesn't increase for large corner reflectors much over about 15dBi. Of course, aiming your reflector would be a bit of a challenge.
No, I haven't taken enough controlled substances to attempt that. Actually, I'm too busy answering usenet news questions to do anything useful these days.
For modeling, I use 4NEC2.
I have some examples posted at:
I also use a variety of specialized deck generators and modeling programs to deal with common constructs and geometries.
For a wide selection of other programs, see:
Interesting. Too bad corner reflectors don't just keep getting better with size. No, I'm not going to turn my room into a parabola :) Thanks for the answer.
Your usenet answers should be in a book. I know I'd sure like something like that in my library.
Cough, cough, cough!!!
Geez, Jeff - warn people when you're going to pull a stunt like that.
A TE11 mode is about the best, and yes this does work. The MAJOR problem is that the hose is very easy to damage, and the VSWR goes out of sight. Traditionally, use of circular waveguide is very limited for two other reasons. First is the lack of polarization stability. You may put a wave in "up and down' motion at one end, but it's anyone's guess what's going to come out the other end. The second problem is mode skiping, as there is little to prevent higher order modes. The main use I've seen for circular waveguide is rotary joints - invariably using the TM11 mode (the equivalent of a probe in the exact center of the end cap). The transition between non-circular waveguide and circular is usually a "hole" between the sidewall of the non-circular guide, and the end of the circular guide.
Extremely crude guess - should be under 2.5 dB/hundred feet. Copper or silver plate would reduce the losses significantly, possibly below 1.0 dB/C'.
What blend of aluminum is this? There's a substantial difference in the conductivity between 1100 (nominal 60% compared to .999 Ag) and6061 (nominal 40% compared to .999 Ag). That conductivity has a large effect on attenuation, as suggested above.
Carrying this though a little further - 4" galvanized steel dryer vent is going to be powdered dog poop compared to solid aluminum of any kind. The only advantage is that it would be stronger, and somewhat less liable to mechanical damage.
I get a very good results from putting a 8 x 4" card covered in silver foil, bent in half to 60 deg just standing close behind the stand of my D-Link G122 USB adapter or Orinoco USB adapter. Regards, Martin
Warning. The following wonderful and clever idea may prove to be no better than useless when actually installed and tested. The author offers no guarantees of functionality or performance and will not be responsible for any subsequent or consequential damages to one's finances or sanity.
Yep. I've done a bit of WG plumbing with WR-90 at X-band in the distant past. Actually, I think I still have some of that stuff buried somewhere. I even have some 2K25 klystrons. Cleaning the garbage out of the choke joints seemed to fix most of the loss problems.
Actually, the stuff I bought is rather solid construction. It's fairly thick and stiff. Seems quite durable. I figure it can be used between floors, around corners, in overhead ceilings, and other places where it's unlikely to trampled or punctured.
Hmmm.... Well, this is a bit different because one end of the WG is directly connected to a polarization insensitive antenna. I was thinking of just a big cone forming a horn antenna. It should accept or belch any polarization.
The feed end is a problem. The 1/4 wave probe will probably screw up badly as the polarization varies. I don't think it's all that important because the polarization from the client radios isn't all that well controlled. They come from all directions and reflections. If it's a problem, I was thinking of a full wave loop antenna mounted perpendicular to the base about .75 wavelengths above the base. If that doesn't play, I have a few ceramic backed patch antennas that should easily fit and are somewhat circularly polarized. If polarization sensitivity really becomes an issue, I'll install two cross polarized 1/4 wave probes and feed them to each of the two access point diversity antennas.
There was a web site showing a Wi-Fi waveguide using galvanized downspout. If that worked, this should be MUCH better.
Methinks for this exercise, I'll abandon 40 years of RF experience and resort to just building it and see what happens. My neighborhood wireless LAN as a dead spot created by a very large tree near the cental access point antenna. I was going to add a 2nd access point but it would be more interesting to see if the flex waveguide can deliver the signal around the tree.
I have no idea. Since it's fairly flexible, it's probable close to dead soft (pure) aluminum. I'll see if I can get some details from the manufacturers.
I didn't know that. That's also assuming that it's not plated, anodized, or alodined. I'm not sure that this stuff has on the surface to keep the high humidity dryer exhaust from etching the aluminium in powder.
I won't damage it. I promise.
Somewhere in cyberland is a long rant I wrote on why the lousy surface conductivity of the average coffee can does not necessarily make a suitable microwave antenna. I also wrote about illuminating the HVAC ducting with wi-fi in a hospital for improving the coverage. That worked but proved unpopular with the administration.
However, even if the results for this waveguide are less than optimum, it does have potential for ducting RF between floors, around corners, and in awkward locations.
Always read the instructions on the package. May contain traces of nut.
Actually, I was thinking about warning people who are about to read one of those gems. Coke/Coffee/Beer does absolutely nothing good to keyboards and monitors.
Yeah, but do you have the weird modified octal socket as well?
How did the garbage get into the waveguide so that it could get into the choke joints in the first place? ;-)
Watch the bend radius - you don't want to distort the cross section any more than possible. The only sample I have here is quite thin - wall thickness is about 0.007 inch.
True - but the other end of the link needs to have a "similar" polarity, or you wind up loosing 20*log of the cosine of the difference in polari- zation. Flaring the end to a shallow cone with the mouth at least several tens of wavelengths across would work, but...
The polarization differs at the mouth of the antenna, or at the coax feed doesn't change the fact that you're not going to be transferring all the signal between "the ether" and the coax.
Circular is a solution - except that to _any_ linear wave, you loose 3 dB. Creating circular polarization in a waveguide would be a nightmare. A better solution is to put two polarization grids a quarter wave apart at the mouth of the horn. BTW, "somewhat circular" is called elliptic, and it's not at all uncommon.
Meaning using one H and one V? That's a much better solution, though there might be VSWR problems. Probably not enough to hurt, but not up to commercial standard.
Well, compared to a similar length of RG58, yeah, but galvanized downspout has got to have more loss than quality coax.
Nothing wrong with that. If the transmitter can tolerate a 2:1 or even3:1 VSWR, this shouldn't harm anything.
That would be what I'd expect. 1100 is a common type, though there is no reason anyone _must_ use Aluminum Association designations.
"Pure" aluminum won't be pure very long. the exterior surface oxidizes fairly quickly, and that oxide is what protects the metal. For this type of service, pure aluminum has an advantage over alloys because any cut or nick is "self healing" (a new coat of oxide forms quickly to protect the interior). Alloys tend to pit when damaged - you see this on outdoor TV antennas and the like, which are often an alloy with magnesium and silicon (the 6xxx series). "Alodine" (I think that's spelled wrong, but what-ever) is just a paint job, and is the absolute bottom of the line for protection..
You might want to see if you can grab a copy of Mil-HDBK-216 which has all you ever wanted to know about transmission lines (including waveguide). The facts on aluminum are MIL-HDBK-694.
Waveguide itself is low loss compared to cable - but the loss is frequency dependent and conductivity dependent. This is why the smaller waveguides are often silver, or at least silver plated inside. At the other end, I have had projects that used 6061 Al waveguide (up to C-band), both in solid and convoluted flexible. On the third hand, if we needed a longer run, it was brass or Oxygen Free Copper, possibly silver plated over a rhodium flash.
But be aware that polarization will be important based on that 20*Log Cosine function, and that any damage can have substantial effects. We used to tune the reflections out of waveguide by pressing gently on the wide sidewall of a guide while monitoring the VSWR, and moving along the guide. When you find the spot where pressing gives the greatest reduction in reflections, you took a ball bearing (of appropriate size) and a set of channel locks, and put a permanent dimple in the guide. It was fairly frequency sensitive, but that's how we got return loss below -30 dB (1.07 or so).
If you could find it, what would be better is "rectangular" aluminum drain pipe (2 x 4 inch inside is about ideal for 2.45 GHz). The loss should likely be under 1.5 dB/hundred feet. The advantage is that being rectangular, you put the feed in the wide wall, and don't have to worry about what it tries to do when the "guide" is bent around a corner. The disadvantage is that it won't make sharp bends.
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