WiFi Woes Part 2 – The Antennae

| by Ken | in Technology Add comments

After having resolved some of the glitchy behavior I was seeing with my WiFi in my house, I wanted to go a little further and improve the signal strength.  The easiest way to do that seemed to be to mess around with the antennae on the two routers.

Router5, the new router on my first floor, is a D-Link DIR-880L that comes with 3 removable antennae.  The router lives in a closet (with active cooling provided by a CoolerGuys setup) but the closet is right near the stairs in a central hallway.  So the location is pretty central but the closed door might be blocking some of the signal strength.  And sure enough, simply opening the door does improve the strength somewhat as measured in a nearby room.  So I figured it was worth getting some antenna extension cables and maybe a little plastic box to mount the antenna in the hallway outside of the closet – keep the closet door shut but still have great signal strength.  If it works well, maybe I’ll paint it all white so it blends in with the ceiling and isn’t quite so ugly to my wife.  I ordered the parts from Amazon (extension cables | plastic project box).

When they arrived, before drilling holes in the plastic box or in the wall next to the closet, the first thing to do was take measurements using Acrylic.  All of the measurements here are averaged over time.  With the antennae mounted on the router in the stock way and the door closed, the 2.4 Ghz band was at -35 and the 5.0 Ghz band was at -45.  With the door open, I didn’t see any change.  Disappointing, because I thought I had before ordering the parts.  Perhaps specific location makes a difference.  Anyway, I continued.  I removed the 3 antennae from the router and screwed them into the extension cables, then left the cables and antenna in the closet, still with the door open.  The signal strength for the 2.4 Ghz improved slightly to -30 but the 5.0 Ghz signal dropped to -47.  Okay, so not a big drop and possibly within a margin of error, but wow, that’s disappointing.  And finally, I moved the antenna out of the closet, extending the extension wire to it’s near full length and taped the antenna to the wall in approximately the location that I’d like to mount the antenna box.  The signal strength for the 2.4 Ghz band dropped to -65 and the strength for the 5.0 Ghz band dropped to -83.  And what’s worse is the 2.4 Ghz band had frequent full drops where it just disappeared.

Well, that was a colossal failure.  I thought the signal strength might not improve that much but that it should at least improve somewhat.  I’m shocked that it got noticeably worse the closer I got to what I thought would be the best setup.  Obviously, I removed the antenna and put things back as it was before.  And the signal strength did return to the original values.

Oh, but before I tried putting the antennae back on the router in the original configuration I did try tweaking settings in dd-wrt to see if I could improve the signal strength that way.  No change.  And in one case, increasing the TX power on one of the bands actually worsened the signal strength of the other band.  Super strange.  But suffice to say the standard settings and standard equipment are standard for a reason.  Monkeying didn’t help here.

Even though that didn’t work out, I was pretty sure my plans for router3 would improve things for me.  I actually had planned on modifying router4 which had just been taken out of service and replaced by router5, assuming that if I broke something, no big deal since I wasn’t going to use that router anyway.  So I ordered the kit from eBay to work with router4, a WNDR3700v4.  The eBay kit I found was for v3, but it would work for v4 too.  However the more I thought about that plan after I ordered it, the worse an idea it seemed to take the router that had been acting flaky and modifying that.  Especially if I am right that the flakiness was inside in the hardware and not a result of antennae or firmware.  So I decided to modify router3 – still a WNDR3700 but a v2 instead of v4.  Neither version of the router includes any external antennae which is why I was confident that external antennae would be an improvement.

Before I began the modification, I tested the signal strength with Acrylic again.  Like with router5, I was in an adjacent room and checked various conditions.  All were pretty consistent that the 2.4 Ghz signal was at -42 and the 5.0 Ghz signal was at -50.

I next upgraded the firmware on the router.  It turned out to be a real challenge to do because the dd-wrt version that was on it was really old and was from a different generation.  The flash update didn’t work so I had to load the img instead, then flash it with the bin files.  And somewhere in there I had to do a 30-30-30 reset which meant reloading my settings.  Eventually I got it updated and tested the signal strength again.  The values were the same as before the firmware update.  Guess I could have skipped that – oh well.

Time for the modification.  I was surprised right away when I opened up router3 and discovered that there were only two antenna connectors.  A visit to the seller’s web site turned up instructions for the kit for the v2.  I had ordered the one for the v4 but I needed the instructions for the v2 because it showed the schematic of the inside of the v2.  Apparently there are only 2 antenna for the 5 Ghz band and the antenna for the 2.4 Ghz band are embedded in the main board of the router.  Well, that’s a little disappointing since I could have bought a cheaper kit but it shouldn’t be a functional issue for me since the 2.4 Ghz band signal is actually acceptable for router3.  It’s mostly the 5.0 Ghz band signal that I wanted to improve.  I proceeded with the drilling of the holes in the case which was pretty easy to do (and I’m really glad I tried fitting the pieces together to realize that I would only be able to use two antenna before I drilled 4 holes!).  I discovered that you really need to tighten the screw mounts in the holes of the case because you want them tighter than the antenna collars which are pretty tight.  (Otherwise, when you move the antenna, you end up unscrewing the mount rather than rotating the antenna on its collar.)  The mod was pretty easy and the parts from the eBay seller’s kit fit well.

Now with the mod completed, I powered the router back up and ran the test again.  Not too surprisingly, the signal strength for the 2.4 Ghz band, with the antennae remaining embedded in the board didn’t change.  The signal strength for the 5.0 Ghz band went down to -60!  And to make matters worse, the 2.4 Ghz band had frequent drops to nearly fully cutting out.  Apparently, the change in antennae profile was causing interference of some sort?  Wow, that’s super disappointing.  I had to undo the changes by putting the silly little PCB-style antennae back into the WNDR3700 v2.  I tested again after putting it back together with the original equipment and yep, back to the original values of -42 for 2.4 Ghz and -50 for 5.0 Ghz.

And as I did with router5, I did try tweaking the TX power and other settings for this router.  And as happened with router5, router 3’s signal strength went down or stayed flat regardless of what I did.  The best I could get is the way it started.

So I spent a day playing with lots of settings, trying new ways of setting things up, experimenting with modifications, and watching a network signal strength graph only to arrive at the conclusion that the original hardware and default dd-wrt settings yield the best signal strength.  But there still must be more I can do.

One Response to “WiFi Woes Part 2 – The Antennae”

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