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Thread: Band 71 vs Band 12

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    Band 71 vs Band 12

    Noticing on a local site that have both band 12 and 71 even in the lowest signal I rarely see band 71. Band 71 is always weaker than band 12 so it rarely appears. What would cause lower signal on 71 than 12. Placement of panels? Or signal level etc? hardware specs?

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    Band 71 may have lower priority than band 12. The two bands don't CA with each other so you won't see them at the same time.
    Donald Newcomb

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    Quote Originally Posted by DRNewcomb View Post
    Band 71 may have lower priority than band 12. The two bands don't CA with each other so you won't see them at the same time.
    Yeah true, I have seen in Philadelphia and some of the suburbs where band 71 is top priority speeds are very fast on LTE. Also I saw a band 71 where it said Clearwire was the carrier yesterday on 71 in northern suburbs near Doylestown

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    Could be many reasons. Antenna height, RRU transmit power, power spectral density of each channel, RF receiver sensitivity of your phone, etc.
    Want to learn more about how LTE works?
    https://productioncommunity.publicmo...ls/td-p/130581

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    Quote Originally Posted by DRNewcomb View Post
    Band 71 may have lower priority than band 12. The two bands don't CA with each other so you won't see them at the same time.
    Had an interesting talk with one of the T-Mobile techs on Friday. She had mentioned that many of the recent phones have had bad antenna for B12 and worse for B71. Good enough to pass FCC, but not much else. She had told me that pretty much anything prior to 5G phones (S20 5G, V60) were not good. I have no real way to validate this, outside of stating that B71/B12 typically are lower priority on my device, and typically don't get much use.
    As far as 'rural' coverage, where it would make a real difference.. I couldn't say (LG G7).
    AT&T... your world, throttled.

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    Quote Originally Posted by formercanuck View Post
    .... She had mentioned that many of the recent phones have had bad antenna for B12 and worse for B71. Good enough to pass FCC, but not much else. .....
    Entirely possible. Since no phones have a way to attach a real antenna, it's hard to test.

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    Quote Originally Posted by DRNewcomb View Post
    Entirely possible. Since no phones have a way to attach a real antenna, it's hard to test.
    I have read that the higher the SAR levels are, the worse the antennas are.

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    Quote Originally Posted by Joeybutts View Post
    I have read that the higher the SAR levels are, the worse the antennas are.

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    I don't understand this comment at all.

    Specific Absorption Rate is a measurement of RF that is absorbed by the human body. There may be instances of certain devices that emit or leak RF due to poor antenna implementation, but there isn't a relationship between RF output and "quality" of antenna. Device testing by the FCC demonstrate that the device remains within acceptable parameters for RF output under all possible scenarios. In other words, they don't let manufacturers just boost the transmit power way up so that you get a better connection, that would cause the device to exceed SAR parameters.

    So perhaps there are some leaky or poorly designed antennas that require the transmit power to be lowered in order to keep within specific SAR requirements.

    Generally speaking, it becomes more difficult to design and manufacturer quality antenna implementations the lower the frequency band. Lower frequencies have longer wavelengths so the antenna must be larger. That said, it would hardly be surprising if some phones had poor reception on low band frequencies but were otherwise fine. Often the antennas share multiple frequencies and there is complex RF filtering in the RF frontend that makes it all work. My guess is that some phones have great reception with low band and others are very poor...

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    Double post, can delete

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    Quote Originally Posted by formercanuck View Post
    ...As far as 'rural' coverage, where it would make a real difference.. I couldn't say (LG G7).
    I can say. Until T-Mo turned on band 71 here I had no, nada, zip, zero, zilch T-Mo signal at home. Now it is there and solid, but not fast. I think they used most of the spectrum on 5G.

    Before band 71 there was some band 12 around town, like 5x5. It never got to my residence. Maybe it wasn't pointed in my direction.

    Verizon still rules here. I expect T-Mo to continue getting better, but they still have a long way to go here.

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    I've mentioned this before in other threads:
    I've lived in and driven through many band 71 areas for months and I've only seen my phone connect to a band 71 tower once. Maybe with a 5g phone, things may be different but band 71 is just not a priority on any 4g phone I have used at all.

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    Depends on the area. Seeing band 71 more than expected in rural/semi-rural areas here. (Manassas, Gainesville & Catharpin, Va) Only had T-Mobile for 2 weeks & it is pretty close to AT&T. Verizon is still king for call reliability where tested so far.

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    I mapped some B71 (and B2/4) on my bike ride today. No B12 here so B71 is definitely utilized on sites that have been upgraded with it and B2/4 won't reach. YMMV and other standard disclaimer apply, of course.

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    On the showing B71 weaker than B12, I can show that B12 was better than B71, but I'm also comparing 10MHz of B71 to 5MHz of B12... So not all things are equal. On a similar note, I can get service inside on B71 from a further away tower... Did similarly when B12 was deployed... But better signal on B71.

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