Replacement antennas for 2.4 and 5.8GHz wireless routers - Page 1
Forum section: electronics / rf-microwave

author: rrinker
author_rank: Super Contributor
timestamp: January 27, 2016, 12:17:52 am
content: Does anyone have any experience with these? I see on eBay any number, not all from China even, although I'm sure at the prices they all are and some just ship from US locations. Anyway, they are advertised as 5, 7, and even 9dBi gain - is this just wishful thinking or do any of them actually give a decent amount of gain? I don't need a huge boost, just a bit stronger signal to the living room and if I can do it for a few dollar's worth of antennas instead of a full on repeater, it would be a bonus.

author: TheSteve
author_rank: Unknown
timestamp: January 27, 2016, 12:31:58 am
content: You might get a bigger improvement by moving the existing router antenna(s) around a little and/or changing channels. I tried some higher rated gain antennas one time and they didn't work as well as the factory originals. I am sure there are some that will work better depending on design, available ground plane etc. Technically as you increase gain performance will improve in one plane while being reduced in another, so if you're covering multiple floors they may work against you.

author: rrinker
author_rank: Super Contributor
timestamp: January 27, 2016, 01:03:35 am
content: My router has 4 antennas, so I have them all oriented differently - it helps with my iPad and iPhone. What's killing me is my Roku Stick, with the changed placement of the TV, LOS is now almost diagonally through the screen and (possibly, not sure of the internal arrangement) circuit board. It's also some 10 feet further away. Former location had a nice direct path (through some interior walls) with no metal or electronic devices between them, and it worked great. It connects, but with too poor a signal strength to actually operate. I'm pretty sure the only way I can fix this is to get a repeater and put it in a position with clear LOS to both the router and the Roku. I actually get decent signal out back on the patio with my ipad, and that's MUCH further distance, through 2 interior and one external walls. All on the same level - I haven't experimented with the basement yet, but the rest of my house is all one floor. My other option is to just ditch the Roku Stick and get a Roku 2 or 3 and run an Ethernet cable through my basement and up to one of the gig ports on my router.Edit - the TV itself gets a nice solid signal - but it only uses 2.4GHz G and has insufficient bandwidth for HD streaming - not to mention no handy app (I use Plex on the Roku)

author: G7PSK
author_rank: Super Contributor
timestamp: January 27, 2016, 10:02:49 am
content: I used one some time ago, found that the extra gain was at the expense of being highly directional to the point that moving a few feet either side of the antenna when close reduced the signal to the point that it dropped out it did enable me to get a signal the other end of the house though. The router I now have dose not allow for external antennas so I no longer have the unit.

author: Delta
author_rank: Super Contributor
timestamp: January 27, 2016, 01:20:37 pm
content: I recently made one of these for use on a 2.4GHz (analogue) video link, and was AMAZED with the results!WindsurferMight even get a Blue Peter badge out of it! :-)

author: cdev
author_rank: Super Contributor
timestamp: January 27, 2016, 01:46:41 pm
content: The long add on antennas people buy for extending router ranges are usually collinear antennas which means they should be placed straight up or that gain is totally wasted. They have an omnidirectional, doughnut shaped pattern, which is good for coverage over a wide area because typically one wants it all at the horizon.But that's not your specific problem. It sounds like something is quite wrong if your router cannot function properly at such a close range. Maybe there is interference or something is blocking or breaking the receiver antenna. Or perhaps as you said the 2.4 GHz band is just not adequate for the bandwidth and S/N your application requires (that kind of makes sense but it also means that youre sending a lot of signal around over the airwaves when a wired connection would make a lot more sense)I would not waste money on an add on antenna unless its really cheap as higher gain at the horizon likely isn't what you need right now.That said, if all else fails, perhaps locating the AP/base station in another room to get around the placement of stuff around the TV would help.Another experiment which could help is adding some kind of reflector behind the antennae, maybe.Or make an antenna and pigtail. (antenna easy, pigtail is more critical and harder to get right without the right connectors, crimper, etc)Start with putting some kind of reflector behind the router antennas - Aluminum foil would be fine for that.

author: rrinker
author_rank: Super Contributor
timestamp: January 28, 2016, 03:07:12 am
content: Somehow we got on 2.4GHz - my router is dual band and the device that is having trouble uses 5.8GHz 802.11ac. As does my ipad - which works all the way out in the back yard by my pool. Problem is most like in the device - the Roku Stick, which is a little dongle that plugs in to the HDMI port on the TV, It's only slightly larger than a classis old USB memory stick - yet in that volume incorporates 802.11AC plus 2.4GHz (maybe) something for the remote control (definitely an RF remote - not sure what frequency) along with the DSP chip that can decode most any video and audio stream. And has at least some general purpose CPU power to run the user interface. It has no option for an external antenna - what is has can't be more than a basic trace on the board sort of thing. Relative to the router, it's behind the mass of the tv - when the tv was on the other side of the room, the Roku was on the side of the TV directly facing the room where the router is located - nothing but the interior wall between them, and it worked great. The TV just helps things along by having 2.4GHz 802.11g built in - it connects fine. I shouldn't have any 5.8Ghz interference in the house - no cordless phones on any frequency, the neighbors closest to the side of the house with the tv do not have any sort of wifi, and the next closest neighbor (that is broadcasting their SSID anyway) is at 2.4GHz and I am far enough away that I can only get a bare minimum signal and then only if I orient my iPad or my phone just right.Like I said - SWMBO is not likely to change the furniture arrangement around just to fix this, so my best solution is probably stop up to a fancier device like the Roku 3 and just run an Ethernet cable and run it wired. That's actually cheaper than any of the active repeaters I've seen, though I do have a place to locate one that would have direct LOS (still an interior wall in the way) to both the router and the Roku Stick. If I had poor reception out on the patio I'd probably do it, but my stuff works fine out there. I only asked because $20 worth of antennas would be the cheapest operation and RF isn't my thing. I understand some of the concept on antenna design but am in no way an expert. Outside of an outstanding op amp course, I took mostly digital courses in college.

author: TheSteve
author_rank: Unknown
timestamp: January 28, 2016, 03:15:37 am
content: How about a 2 foot HDMI extension so you can position the Roku better?

author: rrinker
author_rank: Super Contributor
timestamp: January 28, 2016, 03:26:05 am
content: I thought about that. Plus a longer micro USB cable for power (my TV isn't one of those fancy ones that provides power on the HDMI). I need to order some other cables anyway, might as well throw that in and give it a go. Cheap enough from Monoprice.

author: cdev
author_rank: Super Contributor
timestamp: January 29, 2016, 01:33:28 am
content: A reflector might be useful because it almost always increases gain.It doesn't know what frequency is involved, it just works, usually. So using your USB or HDMI or whatever extension, you could have it go to a cardboard box with aluminum foil glued or stapled to two of its interior sides making a right angle corner reflector, which you then rotate till both sides are "behind" the device, that will give you several DB of gain in the angle described between them. Two sides should be enough.This is a five minute project you can do with stuff you already have. And if you put some covering on the outside of the box hopefully it wont be ugly. My guess is that 5.8 GHz is a short enough wavelength that even a small box would likely be adequate for this task.

author: rrinker
author_rank: Super Contributor
timestamp: January 29, 2016, 03:50:12 am
content: I think once I just move the Roku to the other side of the TV with the extension cable it will be fine. I'm guessing that the shielding in the TV is what's blocking the signal here. Having the device hanging on a piece of cable will also allow me to try various orientations, since I have no idea which way the antenna is aligned inside it - I suppose I could take it apaaaartand see. Couple of days I will have the cable - didn't have an HDMI extension around, never had a need for one. And I wasn't going to pay local store prices for one.

author: cdev
author_rank: Super Contributor
timestamp: January 29, 2016, 05:57:43 am
content: Its likely putting it on a cable will also get it away from RFI, and that may well improve the connection right there, you might also try putting one or two clip on EMI suppression beads on whatever cable you are using.

author: rrinker
author_rank: Super Contributor
timestamp: January 29, 2016, 01:52:04 pm
content: Well, I did hedge my bet a little - in addition to the HDMI extension I grabbed a long enough Ethernet cable. All else fails, hard wire and get a different player - my old one is hard wire only, but it's one of the first media players and can't handle some of the newer encoding. Suppression beads, not a bad idea. I think I have some in my junk box that might work.