Sprint 4G roof antenna guidance.

When I connect to Sprint 4G from the roof of my house I get values of -83 to -81 and 9 to 11. I am considering your 4G kit that includes the 16db antenna and will get a 250u modem from Sprint. If I use 50ft of coax my understanding is that I should drop my signal strength into the low -70s. Does that sound correct and also does this sound like a logical move to you? In my situation would there be any advantage to going with a -24db antenna instead?

Additionally if I end up needing a second antenna what separation between the 2 antennas is recommended?

yes. 50ft lmr400 cable has an attenuation of about 3.5dB at around 2600mhz. if you consider pigtail & connector losses your effective antenna gain would be about 12dB or about 9dB above what the internal antennas offer.

You are a good candidate for the 16dBi panels. You probably don't need the 24dBi - these are huge, bulky, more pricey and quite ugly and the extra gain really should be used to offset cable losses for long cable runs >> 100ft or for really remote locations that need the extra gain. Also realize in general too much input power outside the spec dynamic range of the modem would cause more harm than good. Too much EIRP would be frowned upon by the carrier. In any case since you could never really precisely predict your results in all cases without empirical data you would have to test it out which is why we offer a 30-day refund with no restocking fees on these items (unless of course you really brutalize the antennas or leave it out in the rain for 29 days ).

As much separation as possible/ practical. Technically it only needs to be separated by a half wavelength minimum (the wavelength of a 2.6GHz signal is only about 12cm in free space) so a foot separation is sufficient. The idea however with MIMO is that you get maximum benefit when the signal received by each antenna is as uncorrelated as possible. The best way to make these signals very uncorrelated is not to orient them in the same direction and have them spatially isolated. In fact the integrated antennas are typically oriented 180 degrees apart. Again typical way to figure out what works best is sweep the orientation while looking at RSSI/CINR results.

Was working now having problems.

I ordered and installed your kit a couple of weeks ago and all was working well. I had readings in the low 70s and CINR of around 15 and I was happy. Last evening suddenly I couldn't connect with 4g at all. Now when I look at the modem settings they jump around wildly especially the CINR. One second it will be 19 and then -2 and then 5 and then 11 and the -12 and then 0 all within 30 seconds or so. The signal strength is also changing and is in the 80s now instead of the low 70s. Nothing seems to have changed physically about the antenna. Just wondering if you have any ideas?

Have you contact Clearwire support to figure out if there's any issues going on with the network? This is the most likely explanation.

If you had previously taken note of what base-station (BTS) you had been connecting to successfully you can determine if you are now consistently connecting to a different BTS (a change in Base station ID as reported on the modem network diagnostics screen). This would happen if your closest BTS has issues so the modem is having to connect using a more distant BTS and occasionally ping-ponging between BTS's as the the signal strengths fluctuate.

I see no one has responded to my question on this subject of getting info from Clear like this. I seriously can't imagine Clear giving out any useful information like this. I think one has to actually try calling them for such info to know what I'm talking about.

My last conversation with Clear tech support went like this:

" OK, I want you to reboot your computer"

Me: " OK, it's rebooted"

Clear: "OK, go next to a window and sequentially turn your laptop 90 degrees at a time to test for signal with your USB dongle."

That was it, there was no interest from them at all in any kind of diagnostic numbers from the Clear Connection Manager.

I wish it was possible to get them to give info like you suggest, I just don't see anyone there either able or willing to go there.

So, what am I missing?

I have had a similar experience with Clear using my USB dongle like the OP has had here. I was not using any kind of antenna, just the USB devise plugged directly into the laptop. It was working fairly well indoors in a fairly marginal area but in their coverage zone. Then one day it just stopped working and I had to climb on the roof with my laptop to get it to work. Clear customer service told me nothing had changed with their towers or service in the area. But I knew better because it had simply and over night downgraded itself. ( and it wasn't temporary, it continued to stay at this downgraded level to this day)

Clearman

wow sorry to hear that. Honestly so far we have an ok impression of Clear from the feedback we have got. But then again this was before all the financial problems they have recently found themselves in, including the layoffs they just announced (15% of workforce is huge) ...

Simply there are three and only three places a wireless system can fail:
1) At the BTS or provider network side
2) In the Wireless RF channel between BTS and mobile client device
3) At the mobile client device

Of these three only 1 & 3 are likely to show an abrupt change.

Problems in the wireless channel as in case (2) are usually gradual - We do have customers who were getting a good signal last winter when leaves had shed and saw their signal deteriorate as foliage or tree canopy increased. Or others who had great speeds when the networks were lightly loaded and saw their speeds degrade as more subscribers were signed on. Also things like channel interference (manifests as poor CINR) are typically sporadic meaning it could work great for a few hours then crap out - in such instances it's nice to identify a pattern since it could be interference in your house (e.g if u got a new wifi router or 2.4GHz device and notice problems only when it's in use). These are however not the most typically failure modes we have seen.

For (3) most likely cause, once you confirm the antenna alignment is unperturbed and cable is still intact, is a lightning strike. Hopefully you have a lightning protector. You would however likely see clear evidence of this on the cabling/connectors/lightning-suppressor.

More often than not culprit is with the BTS/network but what we have seen is that these are usually short-lived issues and go away on their own after a few hours/days. It might be necessary to completely power cycle the device to recover (which for a USB modem is accomplished by a reboot). So if this has been ongoing for several days then it could be your customer premise equipment (CPE/USB modem). If you have a buddy with a Clear device this would be easy to rule out the modem by having them test it out at your house. Also Clear support should be able to run a diagnostic and tell you if everything is configured correctly (yes firmware corruption or misconfiguration do happen - i cant tell you how many times i have had to call tech support on my phone since it started acting funky after pulling an OTA firmware update - same thing is applicable to wimax.

You would need to rule out antenna/cable as the culprit by disconnecting it and using modem on roof or outdoors. If problem goes away it might mean that antenna/cabling is faulty or the signal strength has recently degraded. If you remember what the signal strength used to be then you can determine which is which. The antenna/cables are simple mechanical rugged devices (no active electronics) and other than for a lightning strike they really never just fail arbitrarily.

Unfortunately i doubt tier 1 support has such detailed information. They simply read off their screen if there has been a reported outage and will usually tell you there has been no network changes. You might have more luck with tier 2+. Any provider will constantly evaluate their subscriber base and coverage zone and adjust antenna properties (tilt, beamwidth etc) to provide maximum coverage to maximum users (pure economics) - the unfortunate thing is when you don't geographically fall in the maximum user density coverage zone that they are trying to optimize We have sadly seen this as well although you may get lucky and still manage to pick up a strong signal by re-orienting directional panels/yagis.

(1) I don't unfortunately have a friend with a Clear USB dongle to test to see if his would work better than mine in case the issue is my dongle. It's nearly new, so I have no idea if it is the issue. Gee, maybe this is a service Clear could provide But I understand this isn't your responsibility , of course.

(2) So, when you call Clear, you say, " Could I speak to a tier 2+ technician? " What is your terminology to get to someone who can actually give useful info? I'm sure it helps greatly that you are fluent in this language.

(3) I think this is the closest to what actually happened. And I'm sure it's the last thing Clear is going to admit to me, a paying customer. But this is where an antenna system will come in for me. I need to make the most of the signal I do get. ( I'll remind you I am in their coverage zone)

Unfortunately typically only tier1 support can escalate an issue to tier2 and tier2 to tier3/engineering. Usually if tier1 is able to exhaust all their simple troubleshooting script items like telling you if there's an outage or telling you to reboot your computer or move your dongle around the room (or other trivial things that you would probably have already done before you called them but will just humor them by repeating) then they escalate you to tier2 support. Tier2 are typically the real technicians and/or really experienced folks who will start to make sense.