Ideas to block the Wifi AP from neighbours ? - Page 1
Forum section: electronics / projects

author: Kjelt
author_rank: Super Contributor
timestamp: March 11, 2015, 09:31:32 am
content: Hi in the news here in the Netherlands recently that since households nowadays have an average of 6 apparatus with Wifi enabled the 2,4GHz band is getting swamped and the potential down/up bitrate is collapsing.I was wondering is there a simple and practical way of shielding ones houshold from the Wifi AP from Neighbours? Anyone done that?I am not looking for a full cage of Faraday as in the movie "enemy of the state" but if I can get a couple of dB's reduction from their AP's it would be nice.Any ideas?

author: 8086
author_rank: Super Contributor
timestamp: March 11, 2015, 09:32:58 am
content: change channel.everyone here has wifi too, but the speed is just fine. i suspect your issue is not the neigbours.

author: Kjelt
author_rank: Super Contributor
timestamp: March 11, 2015, 09:37:53 am
content: Quote from: 8086 on March 11, 2015, 09:32:58 amYeah done that, most AP's have auto channel switching, I set it to another fixed channel still not a big improvement.There are (as I believe) only 3 real channels in the 2,4GHz band, the rest are subchannels.

author: Rerouter
author_rank: Super Contributor
timestamp: March 11, 2015, 09:38:14 am
content: if you dont mind getting on the grey edge of the FCC, switch your routers region to one that supports up to channel 13, he tends to be free in most areas, as most devices by default stop at 11,if you can find a channel analyser bit of software, look at what channels are already in use, ideally you want to sit in the biggest gap of what is already in useif you want to start wearing a black hat, you could try default passwords on your neighbors AP, and change the settings to move it to a far end channel, to clear a gap,

author: Psi
author_rank: Super Contributor
timestamp: March 11, 2015, 09:41:26 am
content: Use your phone and run a wifi scanning app, they can show you all the channels and signal strength on each. eg Wifi Analzer on android app storeThen you can find the best channel to run your wifi on.Sometimes if you change country in you device you can enable channels that are technically not legal.

author: Howardlong
author_rank: Super Contributor
timestamp: March 11, 2015, 09:52:30 am
content: Aside from changing channel, in general the 2.4GHz noise floor is much, much, higher now everyone and their dog has it.Your best bet, if changing channel on its own doesn't fix it, or locating your AP above furniture height in the middle of your abode (to minimise path attenuation), is to add additional APs distributed at various locations and connect with CAT5/6 etc. Wirelessly connected "extenders" are generally a waste of space in my experience, and by their very nature add to the noise floor,Also note that channels overlap.For example, in my three bed single storey flat, I run three APs, two on Channel 3 at each end of the flat (they can't see each other wirelessly) and one in the middle on channel 11. It's an old building so has thick walls. 5GHz I find is almost useless, very unreliable unless you're line of sight and only a few feet from the router.At one time I used Homeplug for the AP interconnections, but the reliability of that system was quite bad too, and its bandwidth was variable, although it was far better than relying on wireless alone.I use flat CAT6 cables that can be hidden in the edges of the carpet, and can traverse underneath doors and even externally through windows without having to drill holes. Makes for a very reliable set up indeed.If you name all your APs the same, you can have seamless access throughout.

author: cyr
author_rank: Frequent Contributor
timestamp: March 11, 2015, 09:53:57 am
content: Get stuff that runs on the 5GHz band, usually less busy than 2.4G.And good old Cat5, only use wireless where you really need it.

author: Kjelt
author_rank: Super Contributor
timestamp: March 11, 2015, 09:59:09 am
content: Quote from: Howardlong on March 11, 2015, 09:52:30 amAh ok so if you can't block them just start transmitting with more power backGood tip though, i do use a wireless extender but once a month it needs a hard reset , more a PITA than a blessing, so replacing that one with an extra wired AP might do it

author: Kjelt
author_rank: Super Contributor
timestamp: March 11, 2015, 10:00:22 am
content: Quote from: cyr on March 11, 2015, 09:53:57 amYeah all my pc's, mediaplayer, hometheater eq. and other stuff are hardwired. It are the mobile devices esp. the older ones that have trouble and the mobile devices are expanding rapidly with kids

author: Howardlong
author_rank: Super Contributor
timestamp: March 11, 2015, 10:03:00 am
content: Quote from: Kjelt on March 11, 2015, 09:59:09 amThat reflects my experiences with extenders too, when they worked at all, they tended to have unreliable firmware.Inevitably they will slow down your access because extenders are half duplex, so they introduce latency as well as doubling the net bandwidth requirement in retransmission.Edit: It's not so much that it's more power, it's more that the relative inverse square law distance is minimised to your APs and maximised to your neighbours' APs.

author: Kjelt
author_rank: Super Contributor
timestamp: March 11, 2015, 10:03:40 am
content: Now we are on an electronics hobbyist forum anyway.....is it possible to increase the power of the transmitters of the AP a little bit (20% or so) ? Or does that require rebuilding the entire transmission stage ?Would that help in this case or just add to the noisefloor?

author: Howardlong
author_rank: Super Contributor
timestamp: March 11, 2015, 10:09:27 am
content: Quote from: Kjelt on March 11, 2015, 10:03:40 am20% is probably neither here nor there, 10dB (10x) might make a decent difference, but you'd be operating beyond the regulatory requirements. Similarly you can use more efficient or better sited antennas, but again there are regulatory restrictions on antenna gain and/or effective radiated power.Distributing your APs is the legal and friendliest option.

author: tszaboo
author_rank: Super Contributor
timestamp: March 11, 2015, 10:14:10 am
content: I remember a video where Steve Jobs asks the people sitting on a keynote to switch off all their laptops and phones because there was like 200 wifi APs in the room and he couldnt demo the new iWhatever. It was funny.Wifi certainly wasnt designed to be used this way. I still dont understand why we need one internet connection per household. In a crowded place by the Netherlands or here, I always pick up like 20 APs, a bunch of it with the same name, just to make everything worse. It is like the Cold War of Wifi, when everyone is getting better equipment with MOAR POWAH to have a better reception and escalating the war.The wavelength is like 12 cm, so blocking it would be quite some fun. I've found some paints and wallpapers to do this, but ending the cold war requires de-escalation or all out war (getting shared networks and mesh internet).

author: Kjelt
author_rank: Super Contributor
timestamp: March 11, 2015, 10:21:49 am
content: Quote from: NANDBlog on March 11, 2015, 10:14:10 amThat big? I thought it was much smaller because microwaves have these tiny hole screens in their doors, but you are right it is 12,5cm.Then some grounded chickenwire (we call it that don't know how in english it is called so attached a picture for clarity) between the walls would do the trick?

author: kjs
author_rank: Regular Contributor
timestamp: March 11, 2015, 10:33:04 am
content: Nothing beats the reliability of good old copper connections! The entire house has CAT6 cables into every room from a central switch. Since I have unlimited data on our cellphones they have their WiFi turned off, conserves a lot of battery.My home WiFi is disabled too and if I really have to get a WiFi connection I just use one of the unsecured networks from neighbors. In short: I don't contribute to the WiFi clutter.wrst thing is the amount of junk they meanwhile clutter into the 2.4GHz band. WiFi, Bluetooth, microwaves, IOT.......

author: Kjelt
author_rank: Super Contributor
timestamp: March 11, 2015, 10:38:08 am
content: Quote from: kjs on March 11, 2015, 10:33:04 amThat's what I always thought untill I recently dived into the next gen networks (10G so 10 Gb/s) and those switches have connectors that need an optical converter to use optical fiber connectionsExpensive also those switches (€250 a piece) and the optoconverters are also €200 a piece so for a simple 1 to 1 backbone it will set you €1000 back. I decided to wait till prices drop a bit.QuoteThat is a security nightmare, be very carefull what you do in this case. Rule 1 never ever use an unsecured AP.

author: tszaboo
author_rank: Super Contributor
timestamp: March 11, 2015, 10:40:42 am
content: Quote from: Kjelt on March 11, 2015, 10:21:49 amYour mesh needs to be significantly more dense that the wavelength of the frequency you want to block. I read numbers between 10 and 20, i guess it all comes down to how much decibels you want. Fow a microwave you want less than 1 W to escape from that 2000W, so that is something like 70-80 dB. For wifi you are probably fine with less dB.But this is probably the most expensive way of dealing with the problem (at this point of time in the war)

author: mathias
author_rank: Regular Contributor
timestamp: March 11, 2015, 10:50:16 am
content: Again, if you don't mind regulations, you can hook up a directional antenna. These can give 10dB of gain in a specific direction.I know of somebody who has a homemade WiFi biquad in the basement and aimed up towards the sky. Clear and strong reception up to the highest floor.Because this will not interfere (too much) with the neighbors, I don't think its a bad solution.

author: kjs
author_rank: Regular Contributor
timestamp: March 11, 2015, 11:04:54 am
content: Quote from: Kjelt on March 11, 2015, 10:38:08 amyeah, especially if you use a winDOS open backdoor machine.... Nope, it's just maybe once a year for some testing......

author: Kjelt
author_rank: Super Contributor
timestamp: March 11, 2015, 11:09:13 am
content: Quote from: mathias on March 11, 2015, 10:50:16 amCan you give some example, i find this but I think this is an amplifier of somesorts? 100W seems like I will shut down the whole neighbourhood which is not my intentionhttp://www.dx.com/nl/p/2-4ghz-100w-18dbi-directional-high-gain-18-unit-antenna-for-wifi-wireless-network-sma-34759?tc=EUR&gclid=CMbyuOyToMQCFcjHtAod3C8AFg

author: lapm
author_rank: Frequent Contributor
timestamp: March 11, 2015, 11:11:11 am
content: You cant do much. maybe renovate house to Faradays cage? Lead glasses, copper net in walls, etc...yes i understand your pain, my neighborhood is full of AP's, hence i use wired connection when i need speed...

author: owl_uk
author_rank: Contributor
timestamp: March 11, 2015, 11:13:42 am
content: Have you thought about changing the antenna on your access point? Different antennae have different radiation (and therefore absorbtion) patterns. If you can find one which is more directional you might be able to have it 'see' signals from within your flat more clearly than those from your neighbours, e.g. if it has a big front lobe you could have it at the back of your flat pointing into the street. You'll get good attenuation for signals coming from above/below/left/right and in front/behind is either your flat or nothing much.

author: Kjelt
author_rank: Super Contributor
timestamp: March 11, 2015, 11:15:27 am
content: Quote from: owl_uk on March 11, 2015, 11:13:42 amUnfortunately my router/AP is a Fritzbox AP which has sharkvin antennas which are part of the embodyment of the router. I might open it up and disconnect the antenna and attach new anttenna with coax cable for experimentation.

author: dexters_lab
author_rank: Unknown
timestamp: March 11, 2015, 11:21:21 am
content: Quote from: Kjelt on March 11, 2015, 10:03:40 amoutput power is usually software controlled, if you have the right firmware. It does help a little, but doesn't help the signal from your laptop/phone etc back to the AP.I have always used a wifi scanner, located the quietest channel and stuck to it, thinking that if my wifi is always here on channel X then others shouldn't hop onto the same channelhigher channel numbers are usually quieterFinding the best location in your building for the AP also helps

author: GreyWoolfe
author_rank: Unknown
timestamp: March 11, 2015, 12:38:46 pm
content: Quote from: Kjelt on March 11, 2015, 11:09:13 amAnd cook bacon at the same time. You can make simple cantennas that don't have extreme gain like that antenna but give directionality and decent adjacent signal rejection.

author: cosmicray
author_rank: Frequent Contributor
timestamp: March 11, 2015, 01:04:19 pm
content: There are several kinds of interference you may be seeing.First, there are devices operating on the same channel as you with the same channel width. Those are probably the larger issue here.Second, there are devices which may be operating on 2.4 GHz channels, with different center points and channel widths. Some of those devices allow for tweaking the center point one way or the other. An example of this is the Ubiquity 2.4 GHz radios that are used by ISPs on towers and CPE. My Ubiquity CPE radio is currently showing ...QuoteDepending on how close you are to the tower, that might cause problems if your channel overlapped with it.Third, there are the devices which use RF energy for non-communication purposes, and may cause interference (e.g. microwave ovens).

author: mathias
author_rank: Regular Contributor
timestamp: March 11, 2015, 01:15:09 pm
content: Quote from: GreyWoolfe on March 11, 2015, 12:38:46 pmActually it can handle 100W, it's not an amplifier. It's also specified for 75 Ohms, so you get some reflections with your 50 Ohm cable. What you could do is use this:http://www.dx.com/p/2-4ghz-2000mw-802-11b-g-n-sma-wi-fi-amplifier-booster-silver-103137#.VQA_QJ_0-00, which will give you 2W.However, I would recommend you to go all the way and buy a travelling wave tube with several 100's of watts of power.

author: nitro2k01
author_rank: Frequent Contributor
timestamp: March 11, 2015, 01:19:07 pm
content: Quote from: Kjelt on March 11, 2015, 10:38:08 amWhat does all of that really have to do with the conversation at hand, though? cat5e copper cabling can carry a gigabit connection and will last you a long time. Waiting for 10GE is not a good reason to avoid setting up copper ethernet cabling, unless you are planning to set up a small datacenter at home or something.kjs's point was thatanywired connection will have virtually zero interference and is likely the way to go for any stationary computers, and even a laptop while situated at a desk.

author: Kjelt
author_rank: Super Contributor
timestamp: March 11, 2015, 01:41:08 pm
content: Quote from: nitro2k01 on March 11, 2015, 01:19:07 pmNothing, sidetrack.QuotePoint taken and I do that for as much equipment as possible but only in my household there are 5 ipads, 4 smartphones I have hue bulbs on Zigbee 2,4GHz and I probably forget some other stuff. So unless you can tell me how to connect my iPad to a Cat5 cable the whole Cat5 discussion is off topic

author: Kjelt
author_rank: Super Contributor
timestamp: March 11, 2015, 01:42:41 pm
content: Quote from: mathias on March 11, 2015, 01:15:09 pmYeah problem solved, brains fried game over

author: richard.cs
author_rank: Super Contributor
timestamp: March 11, 2015, 01:59:41 pm
content: Quote from: Kjelt on March 11, 2015, 10:21:49 amWe call it chickenwire too, we tend to call the square/rectangular one welded on the crossings "weldmesh".

author: macboy
author_rank: Super Contributor
timestamp: March 11, 2015, 02:09:57 pm
content: The usual response is "change the channel" to use a different channel than the offending device. This is bad advice when the other device is also a WiFi access point.Consider that the 2.4 GHz space is only wide enough for 3 non-overlapping Wifi bands, but has 11 channels (may vary a little worldwide, but this is nominally the case). You could use channel 2 and your neighbor channel 1, but then 80% of your signals will be overlapping. And since you are on different channels, your two different Wifi networks will not 'share' the airtime, but simply transmit over top of each other. This blows away the signal to noise ratio and the speed plummets. To make matters worse, 802.11N calls for two adjacent bandwidth blocks (e.g. channel 2 and 7 or 1 and 6) when using >150 MBps speeds. Then there are NO completely non-overlapping channels that you can use to avoid interference from the other person's WiFi network.The best advice when there is a strong WiFi nearby, is to use theSAMEchannel as that one. Then all devices WiFi devices on both networks should detect when another device is transmitting and wait for free airtime. Your raw speed can stay high but you will share overall airtime, which isn't nearly as bad as the alternative of having your speed drop from several hundred MBps to single-digit MBps.The other alternative which may require buying hardware, is to use the 5 GHz bands. Depending on where you live, there can be dozens of channels and several completely non-overlapping groups of channels.

author: LaserSteve
author_rank: Super Contributor
timestamp: March 11, 2015, 02:11:26 pm
content: TWTS are so old school unless your doing narrow band EME.... FETs now approach TWTs in power at 3 Ghz.That said,Most handhelds and laptops have crappy low gain antennas by design. Most of them are so crappy that the only way to beat that indoors is to go to MIMO or gain antennas at the AP. Every additional AP raises the noise floor, Most laptops use a pair of ceramic puck low gain antennas buried behind metal, so the Effective Radiated Power (ERP) is minimal.For laptops I've had luck replacing the internal card with a USB stick to get the RF free of the case and improve the radiation pattern. Even those have low gain "F" shaped antennas by design. Some radiate well, but some cheap clones often do not even have impedance matching to the antenna.Relocate the AP up higher, improve the antenna's gain and directivity. Try Adaptive MIMO. Go to 5.6 Ghz or another band.Adding TX power for "Burn Through" only works if you increase TX power on ALL your devices. Even then you need horrific amounts of power to achieve anything. Antennas with a less spherical radiation pattern are a more helpful investment then adding a B52 style 1 Megawatt jamming device pod to the problem. Bi-Directional amplifiers are for out in the country where you need range but have low background noise floor.Do what the cell sites did a long time ago. Switch to sector antennas by using a 3 elememt YAGI. Cover just your sector.One other thing that is common, your upstream ISP may use adaptive throttling on you. Mine certainly does. The more I download per month, the slower my feed gets until the start of the next month. Check for that. I love my data sheet collection, but PDFs do burn bandwidth.Steve

author: Jeroen3
author_rank: Super Contributor
timestamp: March 11, 2015, 02:33:09 pm
content: Quote from: LaserSteve on March 11, 2015, 02:11:26 pmA bit of laptop uses several antennas in the vertical screen edges. My two dell laptops did. WiFirangeis excellent.Handhelds are crappy because you, a big bag of water, are holding it. Microwave, especially around 2.4GHZ, is not getting through water very good. Put the device on a table, and take your hands 20cm away, it's much better.ISP's in the Netherlands don't throttle until you're using terabytes a month. The cable providers are overbooked, during peak hours you'll be capped anyways.As the news said. Get multiple 5 GHz accesspoints. And use cables to interconnect them. PLC will be horrible in just a few more years.You can also try to collaborate with the neighbours to use 1, 6 and 11 alternating. And get to know the antenna types.Such as the dipole donut, which almost every router uses. changing the orientation can do magic!!!http://people.seas.harvard.edu/~jones/es151/prop_models/propagation.html#Balanis

author: LabSpokane
author_rank: Super Contributor
timestamp: March 11, 2015, 03:06:20 pm
content: Quote from: richard.cs on March 11, 2015, 01:59:41 pmThe wire mesh (we call it expanded metal) that is used below stucco is very effective as a 2.4GHz shield.Otherwise, do what is suggested and use a 2.4/5GHz panel antenna to locally improve your EIRP in a non-interfering direction.Here is an example from L-Com:http://www.l-com.com/tabbeditem_mobi.aspx?id=22307

author: DanielS
author_rank: Frequent Contributor
timestamp: March 11, 2015, 03:57:10 pm
content: Quote from: Kjelt on March 11, 2015, 10:38:08 amYou can use 10GBase-T with cat6 up to 55m or cat6a/7 if you need the full 100m. For runs under 20m, even cat5e might still be good enough.Many router and switch manufacturers launched 10GBase-T top-of-rack switches with 40GbE uplinks in the past year or two, so I would expect servers with built-in 10GBase-T to become far more common in the near future. Some of Intel's newest server chipsets have dual 10GBase-T ports built-in, so I would not be surprised to see 10GBase-T trickle down to desktop chipsets in about five years.It is at least three years too early to think of 10GbE on mainstream PCs since most of them do not even have the internal bandwidth between the CPU and IO hub to gracefully handle that without sacrificing something else.

author: Kjelt
author_rank: Super Contributor
timestamp: March 11, 2015, 04:51:34 pm
content: I was more interested in the 10G because I have my some computers, servers and NAS in the attic and they all share a single 1G to the rest of the house. Sometimes when I watch a full blueray rip download and some other stuff it is full.

author: Howardlong
author_rank: Super Contributor
timestamp: March 11, 2015, 06:43:09 pm
content: Quote from: Kjelt on March 11, 2015, 04:51:34 pmI doubt an optical drive can soak up an entire 1Gbps link.The biggest limitation I face is doing cross-network backups and maintaining reasonable LAN utilisation. Typically I am lucky to maintain 50-60% LAN utilisation although there is software compression on the clients. Typically I need to do direct SSD to SSD to get 100% utilisation, the limiting factor now seems to be the physical spindles of the RAID set that I do all my backups to, however it is getting close to considering what to do after 1Gbps, but 10Gbps infrastructure is pretty expensive at the moment.

author: tom66
author_rank: Super Contributor
timestamp: March 11, 2015, 07:07:23 pm
content: Quote from: Kjelt on March 11, 2015, 04:51:34 pmI have a NAS server and tried an experiment. Using only a gigabit link I could stream three simultaneous copies of Avatar (40Mbits peak, 20Mbits average) with no worries. The data was only in bursts on the line, showing me that the program (XBMC) caches the data into a buffer rather than relying on continuous availability.

author: eas
author_rank: Frequent Contributor
timestamp: March 11, 2015, 08:53:47 pm
content: The people advising increasing transmit power aren't thinking very hard.As soon as you do that, your neighbors are going to try to find some way to deal with the increased interference from your AP. If you are lucky, they might switch to 5GHz, but chances are, they have the same issue you do, and need to support 2.4GHz devices, so, they'll either find a way to increase their transmit power, or they add an extender. Either way, more noise.The best thing is almost certainly more, lower power radios, but it might even be enough for everyone to cut their transmit power back.Also, as macboy said, if you can't get a non-overlapping channel with a reasonable noise floor, you are probably better off picking the same channel as the main interfering device so that WiFi's collision detection mediates shared use of the bandwidth.Try using a dual-band extenders Link them to the main AP on 5GHz, and cut the 2.4Gz transmit power back on all the devices.

author: mazurov
author_rank: Frequent Contributor
timestamp: March 11, 2015, 09:22:08 pm
content: Quote from: eas on March 11, 2015, 08:53:47 pmReducing power is a viable solution only when you have total control. I used to design wireless setups and yes, having four business-grade APs with their TX power set to the minimum covering a conference room with 20 people streaming video to their laptops works very well; however, when some of said people brings in a "travel hotspot" or some other poorly designed Chinese gizmo it kills connectivity for everyone in the room and the only way to fix that is to ask the owner of the gizmo to either turn it off or leave the building.In neighborhood/apartment/dorm settings the only remedy is to switch to a-band while supporting b-band devices with a separate (or dual-band) AP.

author: LaserSteve
author_rank: Super Contributor
timestamp: March 12, 2015, 01:57:37 pm
content: Decently priced antennas, but you must use short lengths of low loss coax (no more then 2 meters) to the AP.http://www.wa5vjb.com/products6.htmlDisclaimer, I nearly hired Kent for a project and did buy him lunch on the corporate dime. He's good at what he does....Steve

author: 691175002
author_rank: Regular Contributor
timestamp: March 12, 2015, 02:08:29 pm
content: I recently moved into an apartment that has upwards of 120 visible 2.4GHz networks. It is awful, I have a fairly expensive dual band router that can't get more than 10 feet of range at 2.4GHz.I have to use 5GHz USB dongles to get reception on devices that do not have dual band. There are only 2 visible 5GHz networks so I don't understand how anybody else in the building gets by.

author: Howardlong
author_rank: Super Contributor
timestamp: March 12, 2015, 02:12:26 pm
content: Quote from: LaserSteve on March 12, 2015, 01:57:37 pmHe is indeed, I don't think I've ever known anyone who knows antennas better than him, particularly at VHF through microwave. He's been doing this stuff commercially for a very long time, way before WiFi ever existed.

author: Kjelt
author_rank: Super Contributor
timestamp: March 12, 2015, 02:17:51 pm
content: Quote from: LaserSteve on March 12, 2015, 01:57:37 pmVery interesting! though a low WAF but with some white cloth before it that's not relevant.I have little antenna/rf knowledge, the url you give provides a pdf of the 2,4GHz antenna and it states 11-12dB average gain (sounds good) but then the frequency plot below it shows a dip around those frequencies. Can you explain this in beginners terms what I see here?

author: LabSpokane
author_rank: Super Contributor
timestamp: March 12, 2015, 03:01:18 pm
content: I believe that what he is showing is the plot of where the antenna is resonant. The patch antenna I posted from L-Com is essentially the same, but with a plastic case and connector. And lower gain obviously...You might consider 5GHz if it is allowed where you live. It inherently will have fewer interferers due to the higher attenuation through structures. As long as you don't need to go through walls, it's a great solution.

author: Kjelt
author_rank: Super Contributor
timestamp: March 12, 2015, 03:06:17 pm
content: 5GHz is for all new devices a good alternative although I than probaly better also place my AP inside the livingroom (at the moment it is in the hallway).For my older devices that have no 5GHz it is no solution ofcourse.

author: Howardlong
author_rank: Super Contributor
timestamp: March 12, 2015, 03:16:40 pm
content: If you're referring to thishttp://www.wa5vjb.com/pcb-pdfs/QuadPatch2400.pdfit's the return loss of the array.The network analyser sweeps with signal and reads how much of the signal comes back. The assumption is that what doesn't come back is radiated, so the lower the reading, the better. It is typically used to show the bandwidth of the antenna and how well matched it is or isn't. They are almost always done with a dB scale, so a -20dB return loss means only 1/100th, or 1% of the power is returned, and that's a good match in anyone's book. There's no hard and fast rule as to what is a good or bad return loss for antennas, but generally between -10dB and -14dB might be considered an acceptable target, in that anything better generally isn't worth tweaking.

author: Kjelt
author_rank: Super Contributor
timestamp: March 12, 2015, 03:19:33 pm
content: Quote from: Howardlong on March 12, 2015, 03:16:40 pmA great thanks for the explanation

author: Howardlong
author_rank: Super Contributor
timestamp: March 12, 2015, 03:23:37 pm
content: Folks, remember that 5GHz has significantly different propagation characteristics to 2.4GHz. It struggles dramatically through masonry for example. It is not a universal panacea. Scattering APsisa general solution: as I mentioned before think about inverse square law, and how that affects both the the signal you're after and the interferer, and the distance to,your device. By having a closer AP to your device, the relative interfering noise becomes much less significant.

author: Electro Fan
author_rank: Super Contributor
timestamp: March 12, 2015, 07:50:20 pm
content: Slightly off topic but recently there have been a few threads on spectrum analyzers. Anyone out there with a SA see any practical uses of a spectrum analyzer to help characterize or address the original topic in this thread? Presumably it would require a SA that could reach at least 2.4GHz if not 5GHz. Seems like analyzing wifi conditions would be a reasonable use of a SA.

author: Howardlong
author_rank: Super Contributor
timestamp: March 12, 2015, 08:29:31 pm
content: You can do, but remember that spectrum analysers tend to take a sample of spectrum by sweeping frequency over a finite period of time, so bursty stuff like wifi means they need to be left accumulating repetitve sweeps taking peak samples over a reasonable period to get an idea of the local environment.One big problem now is that with WiFi and other 2.4GHz services being so ubiquitous, they often have automatic channel choosing algorithms embedded in them, often making manual channel selection only valid for a limited period of time.

author: NiHaoMike
author_rank: Super Contributor
timestamp: March 13, 2015, 01:40:29 am
content: Aside from shielding (e.g. aluminum foil behind wallpaper) and getting 5GHz equipment, directional antennas can be very useful. It could even be as simple as a piece of metal next to the AP acting as a reflector. Homeplug is a good solution where routing new wiring is not practical, but only if there aren't already a lot of Homeplug networks. (That, unfortunately, requires getting some Homeplug equipment to check.) Homeplug over phone line (requires modified equipment) and Wifi over coax are two other possibilities. Neither are currently common (and phone lines are generally dedicated) so it's unlikely you'll see much interference on them.If you get a used satellite dish and put a smartphone where the LNB used to be, you can use it with an app to find where the interfering signals are coming from, which can be very helpful for applying shielding and aiming directional antennas. (And then you can use the dish as an antenna by putting the AP on it!)

author: CatalinaWOW
author_rank: Super Contributor
timestamp: March 13, 2015, 04:05:35 am
content: I don't like the idea of getting in a power war with the neighbors. Shielding actually makes a lot of sense, it doesn't have to be a full Faraday cage to help.The first step is to understand your usage. Things like printers, TVs and other common users of WiFi are relatively fixed in location. The interfering neighbors signals are also probably relatively stationary (in the sense of coming from a small range of angles), unless they are a laptop in the flat upstairs. A reflector a meter or two on a side strategically placed can help a lot. Chicken wire, tin foil, foil wallpaper, even conductive paint. Sometimes it can be a piece of art. You are just putting the some of the same effects that make it hard to cover a large dwelling with WiFi to work. It doesn't have to be grounded, you are just reflecting the energy. If you reflect it directly back you may even help your neighbors signal strength (probably won't like it since it will self interfere at least half of the time, but the other half is great.)Moving equipment like a tablet or laptop that moves from desk to table to sofa and then on to the bedroom is a tougher nut to crack, but a little larger shield can do the job.

author: Zucca
author_rank: Unknown
timestamp: March 13, 2015, 10:15:24 am
content: WiFi is for girls and Apples funky people.LAN cables are for real man (the longer, the better).There is no cure when the radio channel is too busy/noisy. Protocols can help but the tumor will survive.The only hope is to change the carrier frequency or to live in a Faraday cage like rats.

author: Kjelt
author_rank: Super Contributor
timestamp: March 21, 2015, 06:20:32 pm
content: Interesting to see what 6 to 12 cm makes a world of difference in receptionhttps://www.eevblog.com/forum/chat/a-guy-makes-3d-maps-of-wifi-signals-the-results-are-very-interesting!/msg633971/#msg633971