IRC log for #qi-hardware on 20150315

00:06.04Mike25226hmmmm... Do you think researching/making an amplifier would be a better option since, like you said, PCB antennas are fairly standard
00:07.11whitequarkno
00:07.26whitequarkthese are commodity hardware
00:09.48Mike25226Not sure I'm following.  If the design is fairly standard... how else can you improve such an antenna, if not with some sort of amplifier
00:14.26whitequarkwhat exactly do you want to achieve
00:14.52Mike25226better range
00:15.31Mike25226as well as good signal level
00:18.13whitequarkand you want an omnidirectional antenna with an amplifier?
00:19.30Mike25226yeah
00:19.48whitequarkpointless
00:19.52whitequarkand illegal, too
00:20.51whitequarkpointless because signal drops off as 1/r^2 (for a more powerful transmitter), in addition to receiver picking up garbage on the same channel from afar (for a more sensitive receiver)
00:21.40whitequarkyou could a) use a directional antenna b) set up a network out of several routers
00:24.14Mike25226Inverse square law?
00:24.30whitequarkyes
00:26.20DocScrutinizer05generally an antenna with good gain would help. Hardly feasible as PCB antenna though
00:27.12DocScrutinizer05decen ground plane antenna has quite a bit of gain from 2D (omni)directional
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00:28.34DocScrutinizer05however will fail when you want to go vertical between AP and client
00:29.39DocScrutinizer05I.E. a ground plane antenna in attic is rather contraproductive for clients inhouse "under" the antenna
00:30.22DocScrutinizer05use MIMO
00:31.01DocScrutinizer05it basically acts like an adaptive virtual directional antenna
00:31.36Mike25226hmmm
00:31.50Mike25226MIMO is a multiple antenna design right?
00:31.56DocScrutinizer05yes
00:32.29DocScrutinizer05http://en.wikipedia.org/wiki/Mimo
00:33.37DocScrutinizer05also see http://en.wikipedia.org/wiki/Smart_Antennas
00:37.18Mike25226Wouldn't a wireless card have to support it? I'm guessing it's not as simple as  MAIN--= ,   AUX--=  , = is 2 antennas
00:37.38DocScrutinizer05yes, and many wireless cards _do_ support MIMO
00:38.11whitequarkactually, you would frequently encounter cards with literally these ports
00:38.13DocScrutinizer05and it is like they have 2 antenna connectors
00:38.14whitequarkmy latop has one
00:39.44DocScrutinizer05recently I've seen APs with even 3 or 4 antennas
00:39.54Mike25226http://sishardware.com/imgs/a/a/l/o/a/intel_7260ngw_m___2_ngff_wireless___ac_card_867mbps_802___11ac_bt4___0_1_lgw.jpg
00:40.16DocScrutinizer05:nod:
00:41.06DocScrutinizer05unclear if that's one antenna for 2.4 and one for 5, or MIMO-2 with 2 multiband antenna connectors
00:41.51DocScrutinizer05often it's even configurable in vard's registers
00:41.55DocScrutinizer05card's*
00:42.08whitequarkI think 2.4 and 5 usually use the same antenna
00:42.20Mike25226there is only one PCB antenna and both MAIN and AUX go to it
00:42.21DocScrutinizer05usually, but not generally
00:42.22whitequarkread some appnotes, they say it's good enough
00:44.11DocScrutinizer05http://www.intel.com/content/dam/www/public/us/en/documents/product-briefs/dual-band-wireless-ac-7260-bluetooth-brief.pdf
00:46.45DocScrutinizer052x2
00:47.12DocScrutinizer05suggests MIMO
00:48.33DocScrutinizer05http://www.ebay.co.uk/itm/Genuine-Intel-Dual-Band-7260NGW-AN-WiFi-module-802-11abgn-2x2-MIMO-NGFF-M-2-/251849854651  >>Genuine Intel Dual Band 7260NGW AN WiFi module 802.11abgn 2x2 MIMO NGFF M.2<<
00:49.00Mike25226interesting....
00:49.10Mike25226my laptop only uses 1
00:54.23Mike25226watching a disassembly video to verify
00:55.09whitequarkcrack it oopen
00:58.49DocScrutinizer05wMIMO only makes sense with multiple physically distinct antennas. When your laptop only has one, it can't do MIMO
00:59.00DocScrutinizer05-w
00:59.55DocScrutinizer05conecting both antenna jacks of a mimo card to same antenna is contraproductive
01:00.22Mike25226I've opened it before, and was 90% certain it only had one (twice actually).  But I always feel the need to assure myself when i have the smallest bit of doubt.  Guess you could say I lack confidence
01:01.31Mike25226only has one
01:01.45DocScrutinizer05which btw is the reason to call one "main" and one "aux". The "aux" is the one to leave unconnected when only one antenna is used
01:02.36Mike25226Can a PCB antenna act as 2?
01:02.46DocScrutinizer05the card will (either automatically or by config) shut down the "aux" antenna and use only one
01:02.59Mike25226I imagine that would cause issues being that close
01:03.02DocScrutinizer05no, no antenna can act "as 2"
01:03.40Mike25226well, with a PCB... couldn't it be done?
01:03.49DocScrutinizer05sorry?
01:03.56Mike25226just tracing on back and front of PCB
01:04.09DocScrutinizer05that's two antennas, not one
01:04.55DocScrutinizer05however you must keep the antenna area clear of all conducting objects and traces, also of a second antenna
01:05.28DocScrutinizer05IOW one antenna per dedicated area
01:05.30Mike25226This image as an example: http://www.sequoia.co.uk/images/product/png/3364.png   so the front could be lets say antenna 1, and back be antenna 2?
01:06.05DocScrutinizer05this is one antenna in that picture
01:06.30DocScrutinizer05the bottom side of the PCB MUST kept clear of *all* traces and conducting objects
01:06.41Mike25226ahhh, gotcha
01:07.20DocScrutinizer05of course you can have two of those on one PCB, with a small distance between them
01:07.26Mike25226so that confirms that my laptop is only using one antenna, even though both main and aux connect to it
01:07.45Mike25226you mean side by side?
01:08.15DocScrutinizer05I guess that's pretty wrong a thing to do. Unless the data sheet of the card *explicitly* states to do so
01:08.24DocScrutinizer05yes, side by side
01:09.40DocScrutinizer05ideally in more than 1/2 the length of antenna as distance between them
01:09.52Mike25226hmmm, guess I need to take a closer look.  Since it would be pointless to have aux connected if it isn't the case (side by side).
01:10.22DocScrutinizer05you MUST NOT split antenna cables
01:10.28DocScrutinizer05like Y-cable
01:10.40DocScrutinizer05this is generally absolutely forbidden
01:11.06DocScrutinizer05so when your laptop has two antenna connectors, it quite likely has two antennas
01:14.44DocScrutinizer05unless some jackass retrofitted the WLAN DIY without having faintest clue
01:19.09kristianpaulwpwrak: had you had tiem for trying docker?
01:25.47Mike25226Made this picture with 3 figures.  Figure 1 is how my laptop is setup http://oi61.tinypic.com/402uw.jpg
01:26.15Mike25226Figure 2 is what I am thinking I can do.  Figure 3..... I doubt
01:30.34DocScrutinizer05figure1 is BS, done by somebody with no clue about RF basics. Figure2 is the standard setup. Fig3 is obscure, no idea what it means
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01:32.19DocScrutinizer05adamnt rule of RF: one connector, one cable, one antenna
01:32.45DocScrutinizer05you cannot do Y-cables
01:33.39Mike25226hmmm... then lenovo really messed up.... which might explain why my signal isn't better
01:33.49DocScrutinizer05you could add a band splitter to attach two antennas (one 2.4, one 5GHz) to one antenna input. Which would indeed look like fig3 then
01:35.51DocScrutinizer05ech of the "small PCB" in fig3 would need to be a band splitter then, basically a special filter that routes 2.4GHz signals to and from one antenna and 5GHz signal to and from the other
01:36.34DocScrutinizer05and of course this only makes sense when the antennas are actually made for only one band and can't handle the other
01:36.36Mike25226would that be better? (I could be wrong, but it would then use a different antenna when probing/scanning for networks while connected to a network)
01:37.10DocScrutinizer05no, that's not exactly how it works
01:37.56Mike25226do cards only probe when requested to do so?
01:38.03DocScrutinizer05the "advantage" is that the antennas get the signal they can handle.
01:38.36DocScrutinizer05for the antenna it's irrelevant if the card is "probing" or talking or listening
01:43.39Mike25226Is proximity of the 2.4GHz and 5GHz antennas important? Should they be some what distanced?
01:55.59DocScrutinizer05do you even have 2.4 and 5GHz antennas?
01:57.38DocScrutinizer05look, I'm not looking forward to discussing all possible permutations of configuring a multiband MIMO system, with all the gotchas this introduces
01:58.48DocScrutinizer05when your PC has ony one antenna, connect it to "main" and leave "aux" open. When it actually has 2 antennas, you connect one to "main" and one to "aux"
01:59.45DocScrutinizer05antenna *design* is an art rather than a science. Some even say it's voodoo
01:59.55Mike25226I plan to purchase 2 new antennas
02:00.01Mike25226or make them myself for fun
02:00.18DocScrutinizer05and where do you plan to place those?
02:00.45DocScrutinizer05mind you, they need to stay away a few cm from *all* conductive materials
02:01.05DocScrutinizer05even isolated ones
02:01.40whitequarkmy laptop somehow fares fine despite a solid aluminium lid
02:01.53whitequarkwith the antennas at the very bottom of the screen
02:02.27DocScrutinizer05well, when you *know* what you're doing, you can even integrate the antenna into the aluminium case
02:03.01DocScrutinizer05but then user MUST NOT "hold it wrong" X-P
02:04.20DocScrutinizer05the joy of doing RF tests in freefield, without anything resembling sth annoying like a user's hand ;-)
02:05.00DocScrutinizer05"the device works perfectly, unless a planet is near"
02:07.44DocScrutinizer05on a more honest less funny comment: you _can_ design antennas so they work near conducting surfaces. Actually a groundplane is exactly such a design. But you need to know your RF voodoo for that
02:08.30Mike25226I plan to place the antennas flat down on both sides of the keyboard
02:09.07DocScrutinizer05I guess that's about the worst place for antennas you could possibly find in a laptop
02:09.39Mike25226that's where lenovo placed the one antenna lol
02:09.48DocScrutinizer05assuming the kbd has an alu or steel base, and below the antennas would be main PCB, right?
02:09.56Mike25226screen casing is metal
02:10.04DocScrutinizer05see above
02:10.16DocScrutinizer05on a more honest less funny comment: you _can_ design antennas so they work near conducting surfaces. Actually a groundplane is exactly such a design. But you need to know your RF voodoo for that
02:11.23DocScrutinizer05sorry there's no simple answer to your problem
02:12.55DocScrutinizer05odds are whatever you implement DIY in good failth will be inferior than what lenovo implemented
02:14.40DocScrutinizer05so all I can recommend is: get the original service manual for your laptop and check what the manufacturer says how antenna is placed and built and how it shall get connected
02:16.16DocScrutinizer05compare to what you got, and fix any weird "improvements" somebody might have applied (is this a laptop you bought used? was the WLAN card retrofitted by a cheap cheesy repair shop?)
02:16.31Mike25226well, like I said, they use one antenna (or single small PCB).  It is oriented horizontally (flat) to the right of the keyboard
02:17.16Mike25226Whole body is aluminum except the surface with touchpad and keyboard
02:17.39DocScrutinizer05that's all pretty fine but not sufficient info for me to recommend anything better than I already did
02:19.02DocScrutinizer05"there's a small PCB and two cables come from that" is no info an EE can use to give any recommendations
02:20.38DocScrutinizer05for all I know the "small PCB" might even have TWO antennas on it
02:21.08DocScrutinizer05impossible to tell from the available info
02:22.18DocScrutinizer05and "to the right of the keyboard" is not identical to what I understood when you said "flat down on both sides of the keyboard"
02:23.27DocScrutinizer05I understood that as "under the kbd" not as "to the right/left of the kbd"
02:23.59Mike25226Guess I'll just experiment and test.  First like my figure 2 diagram, and then figure 3 after I do some research, using splitters like you said (for fig 3),
02:24.19Mike25226it's to the right of the kbd
02:24.28Mike25226not under the kbd
02:25.09DocScrutinizer05figure3 would only make sense when you had dedicated singleband antennas. Why would you want to do that? it's an inferior solution to a multiband antenna
02:25.11Mike25226Btw, thanks for your help.  Really appreciate it, and I am learning some things I did not know before
02:26.53DocScrutinizer05and excuse when I'm wrong here, but to me it seems you didn't understand what's a band splitter
02:27.29DocScrutinizer05so your "small PCB" in fig3 is pretty unspecific
02:27.31Mike25226Oh, I was under the impression it was advantageous to have them separated  
02:27.47DocScrutinizer05no it isn't
02:28.21DocScrutinizer05sorry afk, busy
02:28.33Mike25226k, thanks again for the help
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03:11.39DocScrutinizer05he's gone, nevertheless prolly the term "band splitter" isn't exactly to the point, rather "frequency-separating filter" or "crossover"
03:32.55DocScrutinizer05or diplexer
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06:32.09wpwrakkristianpaul: hmm no, didn't need to make any mini-VMs yet :)
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07:22.17ahmed89_can you tell me whice psu is better ? this http://i.imgur.com/ntIyCsC.jpg or http://i.imgur.com/RSnEbXM.jpg
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07:40.37ahmed89_m
07:41.09ahmed89_can you tell me whice psu is better ? this http://i.imgur.com/ntIyCsC.jpg or http://i.imgur.com/RSnEbXM.jpg
07:52.24eintopfnormally I would say that with the higher watt value
07:52.35eintopfbut the terminator sounds cool enough
07:53.09eintopf(terminator) has no watt value printed, but it's high enough to burn cables ;)
07:54.07eintopfthe other one has a FAN SENSCACONTROL :D
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