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Wi-fi range extender
So here's the deal. I want to sit in my car in a parking lot and access
wi-fi legitimately in a nearby building. (I'm authorized to use the system and have a password.) The device is similar to an ipod (no phone). I used a passive RF sniffer around the case and found a sweet spot that has significant RF output. What I want to experiment with is a coupling loop over the case sweet spot going to a coax and then a directional antenna. It would be acceptable to simply scotch tape the loop on the case. Any suggestions on the antenna would be appreciated. Wayne W5GIE |
Wi-fi range extender
On 3/26/2016 2:43 PM, Wayne wrote:
So here's the deal. I want to sit in my car in a parking lot and access wi-fi legitimately in a nearby building. (I'm authorized to use the system and have a password.) The device is similar to an ipod (no phone). I used a passive RF sniffer around the case and found a sweet spot that has significant RF output. What I want to experiment with is a coupling loop over the case sweet spot going to a coax and then a directional antenna. It would be acceptable to simply scotch tape the loop on the case. Any suggestions on the antenna would be appreciated. Wayne W5GIE You may have thought about this... You might need to amplify your receive signal, the device (whatever it is) needs to talk both ways. Bob W |
Wi-fi range extender
On 3/26/2016 6:02 PM, Bob Wilson wrote:
On 3/26/2016 2:43 PM, Wayne wrote: So here's the deal. I want to sit in my car in a parking lot and access wi-fi legitimately in a nearby building. (I'm authorized to use the system and have a password.) The device is similar to an ipod (no phone). I used a passive RF sniffer around the case and found a sweet spot that has significant RF output. What I want to experiment with is a coupling loop over the case sweet spot going to a coax and then a directional antenna. It would be acceptable to simply scotch tape the loop on the case. Any suggestions on the antenna would be appreciated. Wayne W5GIE You may have thought about this... You might need to amplify your receive signal, the device (whatever it is) needs to talk both ways. Bob W Whatever you do with the antenna should work in both directions, no? -- Rick |
Wi-fi range extender
"rickman" wrote in message ... On 3/26/2016 6:02 PM, Bob Wilson wrote: On 3/26/2016 2:43 PM, Wayne wrote: So here's the deal. I want to sit in my car in a parking lot and access wi-fi legitimately in a nearby building. (I'm authorized to use the system and have a password.) The device is similar to an ipod (no phone). I used a passive RF sniffer around the case and found a sweet spot that has significant RF output. What I want to experiment with is a coupling loop over the case sweet spot going to a coax and then a directional antenna. It would be acceptable to simply scotch tape the loop on the case. Any suggestions on the antenna would be appreciated. Wayne W5GIE You may have thought about this... You might need to amplify your receive signal, the device (whatever it is) needs to talk both ways. Bob W Whatever you do with the antenna should work in both directions, no? That's the plan. A bidirectional passive system with maximum coupling of the ipod to transmission line. Today I tried a loop pickup at the ipod to some RG-58 that has a pickup loop at the other end. I'm getting nearly the same level with the RF sniffer at the ipod or at the remote end of the cable. One difficulty is that the ipod doesn't transmit all the time, and that affects attempts to optimize the coupling. If I can optimize the pickup loop, I could permanently attach it inside a slip on cover I have for the ipod. I'm drawing a blank on a good/easy to build antenna. |
Wi-fi range extender
Wayne wrote:
So here's the deal. I want to sit in my car in a parking lot and access wi-fi legitimately in a nearby building. (I'm authorized to use the system and have a password.) The device is similar to an ipod (no phone). I used a passive RF sniffer around the case and found a sweet spot that has significant RF output. What I want to experiment with is a coupling loop over the case sweet spot going to a coax and then a directional antenna. It would be acceptable to simply scotch tape the loop on the case. Any suggestions on the antenna would be appreciated. Wayne W5GIE Have you tried making a corner reflector out of something cheap and holding the device inside it as a test? I've done that with cell phones in weak areas; sometimes it works, sometimes it doesn't. -- Jim Pennino |
Wi-fi range extender
Wayne wrote:
I'm drawing a blank on a good/easy to build antenna. It of course depends on the frequency you are going to use. WiFi antennas with gain (both directional and omni) are available off-the-chinese-shelf (i.e. at prices you are not going to beat), but of course you can always use one of the wellknown technologies to make one yourself. i.e. a yagi, loop, doublequad, dish, etc. But first find out on what frequency you are! |
Wi-fi range extender
wrote in message ... Wayne wrote: So here's the deal. I want to sit in my car in a parking lot and access wi-fi legitimately in a nearby building. (I'm authorized to use the system and have a password.) The device is similar to an ipod (no phone). I used a passive RF sniffer around the case and found a sweet spot that has significant RF output. What I want to experiment with is a coupling loop over the case sweet spot going to a coax and then a directional antenna. It would be acceptable to simply scotch tape the loop on the case. Any suggestions on the antenna would be appreciated. Wayne W5GIE @ Have you tried making a corner reflector out of something cheap and @ holding the device inside it as a test? @ I've done that with cell phones in weak areas; sometimes it works, sometimes @ it doesn't. Thanks, I didn't think of that. Obviously, I'm just having fun playing around. I looked on Amazon and saw some 2.4G yagis at a pretty low price. If I get lazy that seems like a reasonable approach. |
Wi-fi range extender
On 3/26/2016 2:43 PM, Wayne wrote:
So here's the deal. I want to sit in my car in a parking lot and access wi-fi legitimately in a nearby building. (I'm authorized to use the system and have a password.) The device is similar to an ipod (no phone). I used a passive RF sniffer around the case and found a sweet spot that has significant RF output. What I want to experiment with is a coupling loop over the case sweet spot going to a coax and then a directional antenna. It would be acceptable to simply scotch tape the loop on the case. Any suggestions on the antenna would be appreciated. Wayne W5GIE You could maybe try one of those very large metal salad bowls from WalMart as sort of a dish reflector.. It helped me considerably in one situation. Good luck. |
Wi-fi range extender
On Sat, 26 Mar 2016 18:31:40 -0400, rickman wrote:
Whatever you do with the antenna should work in both directions, no? No. The gain can be quite different between tx and rx. The usual symptom of a badly designed reflector antenna is that it can hear/see wireless access points at considerable distances, but can't connect to very many of them. Let's take a parabolic dish reflector as an example. The general assumption is that the transmit and receive gains are identical. That's true only if ALL the RF produced by the feed hits the dish and does NOT spill over the edges of the reflector. See Fig 6.0-1 at: http://www.w1ghz.org/antbook/chap6-0.pdf http://www.w1ghz.org/antbook/contents.htm Any transmit RF that goes over the edge is lost and useless. You can also screw things up by using an excessively high gain antenna for the dish feed. Such antennas have a narrow illumination angle, producing a "spot" on the surface of the dish. That reverses the tx/rx situation. In transmit, all the RF produced by the narrow feed hits a spot on the dish, and is reflected in the desired direction. Nothing is lost. However, in receive, the feed only sees RF coming from the spot. The rest of the dish is wasted as any rx RF that hits outside of the spot, will not be "seen" by the feed. Putting a USB dongle at the focus of a dish reflector is the common way to obtain some additional gain. Everything that hits the reflector is reflected towards the feed. So in receive, the gain calculations are fairly close to the theoretical maximum values. However, in transmit, much of the RF emitted by the USB dongle goes in directions that do NOT hit the reflector. Some of these might accidentally go in the desired direction, but most of the RF is lost. What's left hits the dish reflector, goes in the right direction, and if you're lucky, provides some gain. I posted some calcs for this in alt.internet.wireless a few years ago, but of course, I can't find them. I'll try again later. For the tx gain to equal the rx gain, something will need to be done about the tx RF going in random directions. The basic idea is to match the "illumination angle" of the feed with that of the dish. That's done by making the feed directional and setting the beamwidth to match the f/D ratio of the dish. See: http://www.w1ghz.org/antbook/chap4.pdf Putting a reflector about 1/2 wave behind the USB dongle will help some, but a properly matched feed will work much better. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
Wi-fi range extender
On 3/27/2016 1:39 PM, John S wrote:
On 3/26/2016 2:43 PM, Wayne wrote: So here's the deal. I want to sit in my car in a parking lot and access wi-fi legitimately in a nearby building. (I'm authorized to use the system and have a password.) The device is similar to an ipod (no phone). I used a passive RF sniffer around the case and found a sweet spot that has significant RF output. What I want to experiment with is a coupling loop over the case sweet spot going to a coax and then a directional antenna. It would be acceptable to simply scotch tape the loop on the case. Any suggestions on the antenna would be appreciated. Wayne W5GIE You could maybe try one of those very large metal salad bowls from WalMart as sort of a dish reflector.. It helped me considerably in one situation. Good luck. I used a reflector from a work lite and it seemed to help. I was able to pick up the signal from a restaurant across the street maybe 200 feet away. One of these. I think it was under $10. Knowing how cheap I am, it may have only been $5. http://www.walmart.com/ip/Bayco-8.5-...Light/14003467 -- Rick |
Wi-fi range extender
On Sun, 27 Mar 2016 11:07:00 -0700, Jeff Liebermann
wrote: You can also screw things up by using an excessively high gain antenna for the dish feed. Such antennas have a narrow illumination angle, (...) Putting a USB dongle at the focus of a dish reflector is the common way to obtain some additional gain. Everything that hits the (...) Oops. I reversed the order of these two paragraphs. My rant makes more sense in the proper order. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
Wi-fi range extender
On Sun, 27 Mar 2016 14:11:42 -0400, rickman wrote:
On 3/27/2016 1:39 PM, John S wrote: You could maybe try one of those very large metal salad bowls from WalMart as sort of a dish reflector.. It helped me considerably in one situation. Good luck. I used a reflector from a work lite and it seemed to help. I was able to pick up the signal from a restaurant across the street maybe 200 feet away. One of these. I think it was under $10. Knowing how cheap I am, it may have only been $5. http://www.walmart.com/ip/Bayco-8.5-...Light/14003467 Good enough. I'm partial to misusing my Coleman lantern reflector: http://802.11junk.com/jeffl/antennas/Misc/slides/lantern-reflector.html However, using something that might be part of the evil petrochemical conspiracy is politically incorrect in some circles. For a more organic and sustainable reflector, I suggest a salad bowl: http://802.11junk.com/jeffl/antennas/Salad-Dish/index.html Instead of stuggling with the exact location of the USB dongle, you just tune for maximum signal by sliding the dongle in and out of the PVC tube. Also, unless you have a properly matched feed and accurate parabolic shape, a flat plate or corner reflector will have about equal gains. Fullwave flat plate reflector at 2.4GHz: http://802.11junk.com/jeffl/antennas/FullWavePlateReflector/index.html 8.3dBi gain Same diameter parabolic dish: http://802.11junk.com/jeffl/antennas/HawkDish08/index.html 7.7dBi gain In other words, you can do as well (or theoretically better) with a flat plat reflector, as with an approximated parabolic. More abominations: http://www.freeantennas.com https://www.google.com/search?q=chinese+wok+wifi+antenna&biw=1511&bih=859 &tbm=isch https://en.wikipedia.org/wiki/WokFi etc... Remember: The uglier the antenna, the better it works. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
Wi-fi range extender
On 3/27/2016 4:34 PM, Jeff Liebermann wrote:
On Sun, 27 Mar 2016 14:11:42 -0400, rickman wrote: On 3/27/2016 1:39 PM, John S wrote: You could maybe try one of those very large metal salad bowls from WalMart as sort of a dish reflector.. It helped me considerably in one situation. Good luck. I used a reflector from a work lite and it seemed to help. I was able to pick up the signal from a restaurant across the street maybe 200 feet away. One of these. I think it was under $10. Knowing how cheap I am, it may have only been $5. http://www.walmart.com/ip/Bayco-8.5-...Light/14003467 Good enough. I'm partial to misusing my Coleman lantern reflector: http://802.11junk.com/jeffl/antennas/Misc/slides/lantern-reflector.html However, using something that might be part of the evil petrochemical conspiracy is politically incorrect in some circles. For a more organic and sustainable reflector, I suggest a salad bowl: http://802.11junk.com/jeffl/antennas/Salad-Dish/index.html Instead of stuggling with the exact location of the USB dongle, you just tune for maximum signal by sliding the dongle in and out of the PVC tube. Also, unless you have a properly matched feed and accurate parabolic shape, a flat plate or corner reflector will have about equal gains. Fullwave flat plate reflector at 2.4GHz: http://802.11junk.com/jeffl/antennas/FullWavePlateReflector/index.html 8.3dBi gain Same diameter parabolic dish: http://802.11junk.com/jeffl/antennas/HawkDish08/index.html 7.7dBi gain In other words, you can do as well (or theoretically better) with a flat plat reflector, as with an approximated parabolic. More abominations: http://www.freeantennas.com https://www.google.com/search?q=chinese+wok+wifi+antenna&biw=1511&bih=859 &tbm=isch https://en.wikipedia.org/wiki/WokFi etc... Remember: The uglier the antenna, the better it works. Which of those can be bought off the shelf for ~$5? I don't care so much about ugly, I care about easy. Heck, the shop lamp reflector gives you a spare electric socket and includes a mounting clamp! Hard to beat... -- Rick |
Wi-fi range extender
On Sun, 27 Mar 2016 18:13:25 -0400, rickman wrote:
More abominations: http://www.freeantennas.com https://www.google.com/search?q=chinese+wok+wifi+antenna&biw=1511&bih=859 &tbm=isch https://en.wikipedia.org/wiki/WokFi etc... Remember: The uglier the antenna, the better it works. Which of those can be bought off the shelf for ~$5? None of them. However, you can get something for that price at a thrift shop or garage sale. If you want cheap, two pieces of box cardboard and some aluminum foil to form a corner reflector. I don't care so much about ugly, I care about easy. You're not qualified to determine if something is ugly. That's the job of the wife or ladyfriend. I don't know about easy. Everything I do seems to suddenly have become difficult. Today is typical. To get on the internet, I had to "borrow" the neighbors XfinityWiFi (Comcast) connection because mine is down. My TurboTax won't install on XP. Etc. Nothing is easy. Heck, the shop lamp reflector gives you a spare electric socket and includes a mounting clamp! Hard to beat... Actually, I have one just like that. The clamp and swivel joint both slip. Any incandescent lamp over 60 watts burns up. CCFL lamps will shatter when dropped. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
Wi-fi range extender
On 3/27/2016 7:42 PM, Jeff Liebermann wrote:
On Sun, 27 Mar 2016 18:13:25 -0400, rickman wrote: More abominations: http://www.freeantennas.com https://www.google.com/search?q=chinese+wok+wifi+antenna&biw=1511&bih=859 &tbm=isch https://en.wikipedia.org/wiki/WokFi etc... Remember: The uglier the antenna, the better it works. Which of those can be bought off the shelf for ~$5? None of them. However, you can get something for that price at a thrift shop or garage sale. If you want cheap, two pieces of box cardboard and some aluminum foil to form a corner reflector. I don't care so much about ugly, I care about easy. You're not qualified to determine if something is ugly. That's the job of the wife or ladyfriend. I don't know about easy. Everything I do seems to suddenly have become difficult. Today is typical. To get on the internet, I had to "borrow" the neighbors XfinityWiFi (Comcast) connection because mine is down. My TurboTax won't install on XP. Etc. Nothing is easy. Sorry to hear that. Heck, the shop lamp reflector gives you a spare electric socket and includes a mounting clamp! Hard to beat... Actually, I have one just like that. The clamp and swivel joint both slip. Any incandescent lamp over 60 watts burns up. CCFL lamps will shatter when dropped. I don't have any trouble with the joint slipping if the cord isn't pulling on it. I run the cord through the holes in the clamps to remove the moment of torque. I've had it at the top of a floor lamp for years. If you are worried about the wattage, you must be using a very different wi-fi adapter than I am. ;) -- Rick |
Wi-fi range extender
Jeff Liebermann wrote:
On Sun, 27 Mar 2016 18:13:25 -0400, rickman wrote: More abominations: http://www.freeantennas.com https://www.google.com/search?q=chinese+wok+wifi+antenna&biw=1511&bih=859 &tbm=isch https://en.wikipedia.org/wiki/WokFi etc... Remember: The uglier the antenna, the better it works. Which of those can be bought off the shelf for ~$5? None of them. However, you can get something for that price at a thrift shop or garage sale. If you want cheap, two pieces of box cardboard and some aluminum foil to form a corner reflector. There are all sorts of heavy foil throw away cookware/servingware available for well under $5. -- Jim Pennino |
Wi-fi range extender
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