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Linksys High Gain Antennas Reviewed

Discussion in 'Wireless Article Discussions' started by azazel1024, Jul 9, 2015.

  1. azazel1024

    azazel1024 Very Senior Member

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    http://www.smallnetbuilder.com/wireless/wireless-reviews/32774-linksys-high-gain-antennas-reviewed
    More than anything I can't grok how Linksys thinks anyone will spend >$100 on 4 antennas that probably cost them $5. Heck, looking on many an ecommerce website will turn up plenty of fairly reputable antenna manufacturers who charge less than half that.

    Let alone the little known ones...that still have dozens to hundreds of feed back and make pretty decent antennas (considering that I have half a dozen of them laying around and tested extensively, I can vouch for that).

    I will say that the far distance 5GHz improvement is more than I've ever seen out of an Omni. Then again, I've been generally swapping 3-5dBi antennas with 5-7dBi. I have seen similar behavior with 2.4GHz, there are just very tiny gains to be had, unless stepping up the gain SIGNIFICANTLY. It just seems like all you can really get is somewhat better range...which then again is what a lot are looking for.

    Increased range on 5GHz is harder to get, but better performance tends to abound.

    All of my ~2-3dBi increased gain antenna swaps typically have only netted at most 5% increased 2.4GHz performance and generally only at longer ranges (exception, my outdoors AP where moving from 5 to 7dBi seems to have increased performance at medium-far out to extreme ranges by a fair amount, about 8-12% in all locations and I can keep 10Mbps out about 20% further than before (which is around an increase of 50 feet)).

    5GHz just seems to love bigger antennas, especially on ac routers, and pretty much any distance. All of my ac routers see around a 10% gain on the low end up to about 20% in transfer performance just my a nice modest 2-3dBi increase in antenna gain.

    I haven't seen many 200+% increases though (though at extreme range I do see pretty big increases, but the performance is generally so crappy there, I'd never be using 5GHz. So going from an inconsistent 0-700Kb/s (IE transfer just stop for whole seconds at a time) up to about 0-2MB/sec, with transfers only periodically stopping for a second before resuming). I guess if you were to jump several more dB in gain it might make those kinds of locations actually viable for 5GHz, but by comparison I can get about 8.5MB/sec down, constant and smooth on 2.4GHz at that location....
     
  2. Razor512

    Razor512 Senior Member

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    I would love to see him test some of the cheaper $5 "high gain" antennas.

    Also, is it possible to remove some of the plastic casing to see the internals of the antenna?

    I want to compare its build quality to a 5dBi gain antenna that I got from ebay ($1.50 for a pack of 2 and free shipping from China :) around 3 years ago ) (bought a bunch for some WiFi enabled IP cameras (they performed better than the stock antenna on the foscam IP cameras)

    Pic uploaded to dropbox since imgur appears to be in the middle of a DDOS at the moment. https://dl.dropbox.com/s/v3d9ltbxj3qpkn3/Antenna.jpg?dl=0
    sorry for potato quality. I used a flashlight aimed at a sheet of paper for lighting.

    edit, yay imgur is working again

    [​IMG]
     
    Last edited: Jul 9, 2015
  3. sfx2000

    sfx2000 Part of the Furniture

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    @Razor512 - that's pretty much correct...

    One sees the helical - that's the high band, and the long rod is the low band...
     

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  4. sfx2000

    sfx2000 Part of the Furniture

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    And it's not so cut-and-dried with external antenna's other than what the vendor provides. Each antenna design, the engineer is trying to optimize the impedance match to the antenna for the radio in the AP - this goes into deep RF items like VSWR*, Beam Patterns, and other performance characteristics to make sure that the antenna is the most efficient design posssible - at least this is the mindset of the tier 1 OEM's...

    So buying so called - "High Gain" - antennas from a third party can actually harm your performance, rather that help, as it will more often than not, be a mismatch from the OEM design, which may or may not be optimal to start with, depending on the skill of the OEM...

    * VSWR (Voltage Standing Wave Ratio), is a measure of how efficiently radio-frequency power is transmitted from a power source, through a transmission line, into a load (for example, from a power amplifier through a transmission line, to an antenna).
    FWIW - I've been in the industry for a very long time - but my early coursework in college was Analog RF on the EE track - how I ended up doing SW and Digital HLD, along with my current Networking stuff, well, we go where the career path takes us..
     
  5. stevech

    stevech Part of the Furniture

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    I believe that when most savy WiFi users seek "high gain antennas", their problem's shortcoming is on the order of 20dB or more. And a true 9dB WiFi 2.4GHz omni is inconvenietly large.

    And, there a lot of fraudulent "hi-gain" antennas on the market.
     
  6. sfx2000

    sfx2000 Part of the Furniture

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    I think the Linksys kit is pretty much optimized for the WRT1900ac/WRT1200ac family only, so results on other devices could be actually worse...

    Note that the device under test in the article is - yep, Linksys WRT1900ac

    The WRT1900ac is an interesting device for an AC1900 class AP - it's the extra radio - it's 4*4:3, and that extra radio is a 3dB improvement right there, even at the same Tx power, and that extra radio buys at least 3dB on the Rx side as well, and this goes both bands...

    Goes without saying, and I'm not the only one, higher gain has a tighter pattern, and if you're in that pattern, all is good, but that gain turns into a deficit when you're outside of the primary beam pattern - test results are concurrent with my expectations..
     
  7. sfx2000

    sfx2000 Part of the Furniture

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    Agree - and it's high gain compared to what???

    SteveCH - you're probably one of the few that know this stuff - we talk about antennas and lamda, and matching, you get it as well as I can - and you're probably better at it in a practical perspective :D
     
  8. sfx2000

    sfx2000 Part of the Furniture

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    One of the coolest antenna's I've seen recently, and one can tell, this was computer designed and noodled by an expert... it's the business end of the Airport Extreme AC...

    AC1900 3*3:3, with beam-forming, and it's a PIFA with an interesting ground plane... and it performs quite well for a SOHO router...

    This one is art, based in science, but from my perspective, Apple or not, someone spent a lot of time sorting this one out for a dual-band antenna...

    AP_Extreme_AC.jpg
     
  9. stevech

    stevech Part of the Furniture

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    Sorry, I'm in the camp that says beam-forming can work on a cell tower, but not on small and cheap platforms.
    This opinion is based on field experience (not 802.11).

    Happy to defer to hard science if it can be found in WiFi.
     
  10. azazel1024

    azazel1024 Very Senior Member

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    Dunno, beamforming certainly seems to work with Wifi. I cannot disable it on my TP-Link routers, so I can't compare it's impact with and without. However, there seem to be a fair few tests floating around on the internet with routers where you CAN disable beamforming to test. The results seem to indicate that it does provide a pretty favorable bump of about 10-20% in the mid signal range for real world performance (in the 55-75dBm original signal range). It isn't huge, but every bit helps.

    MU:MIMO requires beamforming too.

    Also every radio chain you have, the greater the potential increase in gain from beamforming (plus you have the gain from the extra radio chain itself too).

    Antennas certainly should be optimized, but in my limited testing (Archer C5, Archer C8 and WDR3600, 841nd) all of the routers I have tried have shown an AVERAGED increase in performance over their coverage area ON THE SAME VERTICAL PLANE as the router with as little as a 2dBi increase using decent quality, but relatively "unknown" antenna manufacturers (powersupply anntenas). 2.4GHz just doesn't seem to benefit a whole lot, but does some at medium far to extreme range. 5GHz seems to benefit a lot at all ranges (though 11n doesn't seem to benefit on 5GHz at close range, probably because both 2.4GHz and 5GHz close to the router is easily capable of SINRs for 64 QAM, but at close ranges current electronics have a harder time maintaining the SINR to support 256 QAM as well as 80MHz wide with 11ac, at least that is my guess).

    Above the plane of the antenna you do see a drop, sometimes a big one. There you are in to a multiple AP scenario.

    Then again my house I have my router fairly high up on a shelf in my basement on one side of the house with the antennas canted back at about 10 degrees. Then on my main level I have a router in AP mode on the other side of the house with the antennas straight up and down. Then a router in AP mode in my garage with the antennas run to the outside with them straight up and down. The basement router is running 5dBi and does an awesome job covering the basement and the couple of rooms closest to it above it. The main level AP has 7dBi with the 2.4GHz radio set to low power and does an awesome job covering the rest of the main level and most of the front yard (though not great for the front yard) as well as the garage. The garage AP counter-intuitively doesn't cover the garage and only covers the backyard, but it covers it with awesome coverage (I can get an okay signal in my next door neighbors backyard about 200 feet away through a row of pine trees. With 2.4GHz I speedtested it at 12Mbps down and 5Mbps up on my phone. I was playing beer pong with them and was curious, yes, it is set to a different channel than what he has his router set to).

    If money and power consumption where no objects, an ideal setup to me would be zero hand-off roaming and a 5GHz only 11ac dual stream AP with 3dBi Omni's in an outlet format AP (hardwired) in every room. Not going to happen though.

    I am considering moving to 9dBi antennas outside at some point to test them out.
     
  11. sfx2000

    sfx2000 Part of the Furniture

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    You and I have both done a fair amount of work on beam-forming - my experience with iBurst and 16e (Wimax) - that company did go on to develop the technology further on LTE...

    With beam-forming, the devil is in the details, and implementation is sometimes pretty difficult - even on a single node, but when one goes into a plurality of nodes, RF planning becomes a big challenge...

    802.11ac's beamforming is fairly simple compared to what has to be done on a wide-area basis - and I've actually seen it work fairly well, even cross vendor (Marvell AP to Broadcom/Realtek, Broadcom AP to Atheros/Marvell/Broadcom) which indicates not a lot of inbreeding/proprietary stuff in there..

    MU-MIMO on the other hand, that's a lot more work... but I've been impressed with what Qualcomm/Atheros has done there - and that's only the first of many.
     
  12. System Error Message

    System Error Message Part of the Furniture

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    That does not look like an antenna, still looks pretty cool. with a really large antenna like that perhaps you can use an amplifier?

    I think the laws apply differently for directional antennas
     
  13. sfx2000

    sfx2000 Part of the Furniture

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    There's no active stuff underneath that plate - I got a dead one for free (lightning hit), and took it apart...

    The radiated elements are the traces around the edge, the plate is a passive reflector...
     
  14. sfx2000

    sfx2000 Part of the Furniture

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    And if one thinks the Airport Extreme AC antenna is fairly different, one can check out the WiFi/BT antenna module on the Mac Pro over on iFixit - Most people don't see Apple as an RF design leader, but after iPhone4 and the AntennaGate mess, they got dead serious about RF, and invested huge in RF design and testing, and hired some really, really smart people, and we're seeing the results now..
     
  15. red_pope

    red_pope Regular Contributor

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    Ill have to admit, that on my working experience with WiFi "Generic Antennas" antennas some times is a good option. 5 years ago, My team was assigned to fix the WiFi problem in one of the mail distribution centers, Even do the routers they were using was branded one, the 3dbi antennas was the biggest suspect.

    Their range was weak and losing a lot of data-packets, because those government routers were not talking to each other. After verifying the settings on both routers were correct, we got down and dirty to prove our RF suspicion. Our budget was very tight, we opt to change the antennas to 9dbi, but that was causing more headaches than results, later we swap them to a 5dbi antennas, and that solved our headaches just in 5 hours of labor.

    The over all cost of improving the RF gain was very cheap to the government, a total expenditure of 50 dollars and not like some other independent contractor was trying to milk the government on thousand of dollars.

    Using our test software, a laptop, the through-put was excellent. No lost data. My team earn a spot of better trust with our senior Inspector, knowing the WiFi was not our expertise field. But RF was our strong side, Just 3 guys thinking all the time, how to fix the problem. Automation is big in United States Postal Service. Yet, we still do a lot of manual work, either rain, snow or shine your mail will be deliver.
     
    Last edited: Jul 11, 2015
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  16. red_pope

    red_pope Regular Contributor

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    sfx2000

    I saw the link that you post it, and it is an impressive machine of workmanship and it is a manufacture 100% in the USA.
    I have question?
    Knowing that Apple is notorious to be proprietary, Will their WiFi binary code compatibility with other non-apple products?
    In other words,
    Will this 3000 thousand dollars router work well with others?.
    Is this router consider an Industrial router?

    Thank You
     
  17. red_pope

    red_pope Regular Contributor

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    The soldering points has to be almost perfect and protected properly,(Sleeve rubber cover). Either non-quality and quality product will make you smile or mentally insane trouble shooting, In my opinion that very top antenna is an excellent product has its own design and purpose.
     
    Last edited: Jul 11, 2015
  18. stevech

    stevech Part of the Furniture

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    5dBi antenna versus 2-3dBi stock antenna... negligible
     
  19. azazel1024

    azazel1024 Very Senior Member

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    Uh, well yes of course it will. It is a WiFi router, not a 2.4GHz/5GHz proprietary RF networking device.

    The only "issue" that Apple products really have is that they are fat-channel intolerant on 2.4GHz, no ifs ands or buts about it. 20MHz on 2.4GHz only.

    Beyond that they work very well, if not exactly terribly cheap. I've tried out my older dual band (NOT concurrent) Airport Express. It works very well. I only use it wired through for air play, but I did play around with it as a wired AP and for 100Mbps max ports, it has nice range and performance. My father's new extreme (11ac) works very, very well.
     
    red_pope likes this.
  20. TonyH

    TonyH Very Senior Member

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    And also placebo effect, LOL! Many are snake oil variant. Good ones cost good money. Not only on WiFi, see how many fancy Digital TV antennas for cheap. I 'll never understand digital in front of TV antenna. A marketing ploy!