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The 2nd antenna was the internal antenna of the B593-601
The B593-601 was definitely compatible with the MIMO antenna, provided you selected "external antenna". The only challenge comes in when a B593 has firmware which does not allow one to manually select external antenna.
I am aware that signal strength is not the only guideline, but a massive improvement in signal strength when using the internal antenna, vs external antenna, will certainly give you the first sign as regards whether the antenna is working with the router, or not.
The dc short inside the antennas - I have opened a few antennas now from multiple manufacturers. The dc short is a dead short between signal and ground, at the end of the signal path. it is present on some of our antennas, not all. There is no protection inside the antennas. This dead short appears to be required for routers which have only an "auto" function, for detecting the presence of an external antenna.
The B593-601 was definitely compatible with the MIMO antenna, provided you selected "external antenna". The only challenge comes in when a B593 has firmware which does not allow one to manually select external antenna.
I am aware that signal strength is not the only guideline, but a massive improvement in signal strength when using the internal antenna, vs external antenna, will certainly give you the first sign as regards whether the antenna is working with the router, or not.
The dc short inside the antennas - I have opened a few antennas now from multiple manufacturers. The dc short is a dead short between signal and ground, at the end of the signal path. it is present on some of our antennas, not all. There is no protection inside the antennas. This dead short appears to be required for routers which have only an "auto" function, for detecting the presence of an external antenna.
601 was not working with MIMO antenna in auto selection mode, so calling it compatible is simply not correct. It is a reason behind not liking this antenna. Tower is using 2x2 MIMO mode, router also, but your MIMO antenna (most probably) do not. Technical data published on WEB site indicate it has vertically polarized elements. For 2x2 MIMO operation it would require cross-polarized elements. If you can prove that router was working at this time in 2x2 MIMO mode, then yes, you might say your antenna is compatible with the router.
Not at all. 601 also do not like this antenna. As I wrote before (I see some messages had been deleted) and now there is more evidence from jcheek, DC-short is not used for antenna detection. It must be other factor, most probably 2x2 MIMO compatibily.
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jcheek
Expert Member
Agree 100% with sajunky. On a B593s-601 you can force the unit to use these external antennas, even if the resulting signal conditions are actually worse than with the built-ins. You may still get reasonable signal and throughput, but definitely not optimal.
As a general comment, these discussions will be a lot more meaningful if the relevant RSSI/RSRP/RSRQ figures (as appear when doing a "Wireless Status Check" under System / Diagnosis" on the B593s-601) are quoted.
In my experience, an RSRQ worse than -6dB to -8dB (eg -10dB) in the presence of otherwise good signal strength, is a good indicator that something else is "off".
Again, I agree (mostly) with sajunky.
To operate in 2x2 MIMO mode it would require require cross-polarized elements OR decent separation between the two vertically-polarised elements.
For the modem/router to negotiate a good connection, it wants to see adequate diversity between the two signals arriving on its two ports. That can be obtained either by:
a) Having two orthogonally-polarised elements (here spacing is largely irrelevant - they can be in the same box or on the same boom); OR
b) Having two identically-polarised elements (like two omnis) spaced to give signal diversity (this is spatial diversity). Here spacing is important and must be optimised by experiment, with the basic guideline of "about a metre" outdoors, possibly much less if used indoors.
Looking at the Otto/Chang-Hong PA0727-5MT (dual patch) and the OA0727-5MT (dual omni), they would seem to provide neither of these things : the elements are not orthogonally-polarised (specsheet says both are vertical) and the spacing looks small (like <100mm). To my mind, that is why the B593 does not "like" them - it gets a better signal result with its own built-in antennas.
Referring to jeaninek's situation, I believe (b) above is why she may do much better with the two separated omnis than with the 1-piece dual patch.
As I've said before : I'm prepared to accept that DC continuity might play some role in antenna detection (perhaps more critical on the u-91), but I personally think the detection has more to do with measured signal strength/quality.
I can't say from personal experience how the B593u-12 or 'u-91 behaves (because I don't own or use one). All I can say is that my B593s-601 seems to detect and use my external antenna(s), provided the antenna is in good signal and is properly set up. Interestingly, it is not uncommon to see the '601 use a mixture of antennas when set to "Auto" : an external antenna on one port and a built-in on the other.
Interesting feedback, thanks. How about some photos on the "Antenna installation & alignment thread" ?
Did your autopsies include the PA0727-5MT and the OA0727-5MT, and were you able to confirm if the two elements are indeed, both vertical as the specsheets suggest ?
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It is better to agree with sajunky 100%.
I was refering to this particular antenna design, but not general MIMO antenna options, so above comment do not really apply to my assesment. But thank you for your elaborative post. I have one question regarding highlighted part. Are you saying that antenna with two orthogonally-polarized elements do not need spatial diversity for proper operation?
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jcheek
Expert Member
Well, in this case I happened to agree with what sajunky said about the Chang-Hong antennas.It is better to agree with sajunky 100%.
That is true for the PA-0727 (dual-patch) antenna, yes - it might be more usable if its two elements were orthogonally-polarised.
But remember that other (perhaps less technical) people are reading this thread - the point being made was that one does not necessarily have to have orthogonally-polarised elements (or antennas) if signal diversity can be gained in other ways (like spacing).
Provided the two receiving elements don't interfere with each other - that is my understanding, yes.
If the two receiving elements are orthogonally-polarised, then they provide signal diversity by virtue of picking up signals that were emitted with different polarisation. We have seen quite a few examples on the forum of dual-element, 1-piece receiving antennas that operate on that premise.
jcheek
Expert Member
Before rushing out to buy one, first be sure that you actually need one! As many users' experiences show, the built-in patch antennas on the B593s-601 are already pretty good.
But assuming that you've determined that you need one, you can choose external antennas (omni- or directional) from a variety of manufacturers or importers, with Otto Wireless and Poynting being two examples.
In the case of the Poynting products specifically, Azimuth has made an excellent summary in Post#2 of the Antenna Installation and Alignment Thread.
If you look at other user's experiences, it would be wise to get an actual demo of the antenna you intend to buy, preferably using your own B593 (or one like it), before you commit. Failing that, be guided by actual user experiences as reported on threads like Antenna installation and alignment.
If you can't do either of those things, then rather start small!
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Thank you.
I understand, but my question was specifically formulated in terms of LTE transmission. It is dynamic industry and many camps use the same terms for different purpose. I think we should focus on LTE, not generic "spatial diversity". So I repeat question specifically to the LTE transmission:
Edit 18th of March: I see no response. A hint: search for "spatial multiplexing", it is a proper term in LTE. When you finally understand a rubbish you wrote, I expect embarassment.
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Thank you, and huge respect for Azimuth!
just a question from a noob on the subject: why would one want a "omni directional" antenna? Surely their gain is less than a directional? Would that be if one has to switch between various towers?
PS: sorry, this probably should be in the antenna thread :-(
@CPTBoy appreciated man, thank you.
@Bundu to be technically correct, it's either one or the other. If you have Line of Sight (LOS) or near LOS, go directional. If not, go with an omni. And yes, an Omni will (still) allow polling of nearby cells and dynamically selecting an "appropriate" one to use. However, I've demonstrated before how leaving the choice to polling can screw up your LTE experience completely.
No worries about posting here, I'll have a mod move posts to the relevant sections soon.
@Bundu to be technically correct, it's either one or the other. If you have Line of Sight (LOS) or near LOS, go directional. If not, go with an omni. And yes, an Omni will (still) allow polling of nearby cells and dynamically selecting an "appropriate" one to use. However, I've demonstrated before how leaving the choice to polling can screw up your LTE experience completely.
No worries about posting here, I'll have a mod move posts to the relevant sections soon.
Don't worry, it is about B593 as well.just a question from a noob on the subject: why would one want a "omni directional" antenna? Surely their gain is less than a directional? Would that be if one has to switch between various towers?
PS: sorry, this probably should be in the antenna thread
MIMO works the best in conditions of high SNR with minimal line of sight (LOS).
- For high SNR you look for LOS (on the roof), but you are limited to choices of the antenna. Cross-polarized one gives good channel separation, but do not benefit from advanced LTE techniques combining MIMO with transmit diversity. Former increase bit rate (speed), the later helps improving error rate (reliability). Dual OMNI antenna is not optimal here, but if one element can pickup reflections it will work. Dual OMNI will work with Co-MIMO, while directional one is dedicated to a single tower.
- Indoor enviroments are particularly well suited for MIMO due to the high degree of multipath, but SNR is not favourable.
- Hybrid indoor/outdoor channel configuration rarely works, as both channels should deliver balanced signal strenght, SNR and error rate. Tower is able to adjust power for each channel, but SNR is not under control. However when such configuration is favourable, B593 is able to detect and use it.
These are mutually exclusive requirements which cause that typically internal B593 antenna works very well and adding external antenna don't give expected results. As B593 prefers MIMO configuration, these are challenges cellular antenna installators have never experienced before.
Don't worry, it is about B593 as well.
MIMO works the best in conditions of high SNR with minimal line of sight (LOS).
- For high SNR you look for LOS (on the roof), but you are limited to choices of the antenna. Cross-polarized one gives good channel separation, but do not benefit from advanced LTE techniques combining MIMO with transmit diversity. Former increase bit rate (speed), the later helps improving error rate (reliability). Dual OMNI antenna is not optimal here, but if one element can pickup reflections it will work. Dual OMNI will work with Co-MIMO, while directional one is dedicated to a single tower.
- Indoor enviroments are particularly well suited for MIMO due to the high degree of multipath, but SNR is not favourable.
- Hybrid indoor/outdoor channel configuration rarely works, as both channels should deliver balanced signal strenght, SNR and error rate. Tower is able to adjust power for each channel, but SNR is not under control. However when such configuration is favourable, B593 is able to detect and use it.
These are mutually exclusive requirements which cause that typically internal B593 antenna works very well and adding external antenna don't give expected results. As B593 prefers MIMO configuration, these are challenges cellular antenna installators have never experienced before.
thanks sajunky, most of that went a bit over my head, but I get the idea
Hi there. I can give you 2 reasons why many of our customers are opting for omnidirectional antennas. Firstly ease of installation, as there is no need to "point" it in the direction of a chosen tower. Secondly, with the load shedding, I have personally seen towers go offline. This is a massive pain when you are using a directional antenna, as has happened to me. I then need to go and turn my directional antennas towards the next best tower, and for some people it may not be practical to do so. So the pain factor during load shedding is also one reason why some of our customers have gone for omnidirectional. In terms of gain, we now have a really nice one in stock, which is expensive but compatible with B593. It gets correctly detected by the router. See this link: http://www.otto.co.za/products/ante...omni-directional-lte-antenna-with-12dbi-gain/
thanks! makes sense also when one uses more than one sim card from different ISPs, i.e. different towers - You spoke about your antenna installation "manual" in an earlier post - do you perhaps have a link where we can download it?
There is a MIMO omnidirectional antenna for R590 at Otto.
http://www.otto.co.za/products/antennas/gsm-3g-4g-lte/lte-3g-4g-mimo-omnidirectional-dual-antenna-7-db-with-5-meter-cables/
http://www.otto.co.za/products/antennas/gsm-3g-4g-lte/lte-3g-4g-mimo-omnidirectional-dual-antenna-7-db-with-5-meter-cables/