Why do TMAs have to be mounted near the antenna of the basestation? Is there any technical restrictions for mounting the TMA near the BTS?

I have never seen a TMA inside the shelter near the BTS; all are mounted high on the mast next to the antenna. This way, they are difficult to service, especially in bad weather.

  • I have to say, when I read your question, I had no idea what a TMA or BTS was. But after 30 seconds of quality time with Google, I could figure out the answer. – Ron Trunk Mar 9 '15 at 0:55
  • @Ron this is great. I was searching for more than an hour and couldn't find it. Can you tell me what you have found? – vladiz Mar 9 '15 at 8:08
  • The longer the cabling between, the more loss. What equipment are you specifically talking about? Brand? Product line? Cellular or ISP? – user14320 Mar 12 '15 at 3:57
  • @it_monkey I think the the equipment brand doesn't matter, they mount it on different cellular equipment, I think I have seen TMAs on Huawei, Nokia-Siemens and Alcatel-Lucent 2G and 3G. But I don't know the brand of the TMA. – vladiz Mar 12 '15 at 7:25
  • Did any answer help you? if so, you should accept the answer so that the question doesn't keep popping up forever, looking for an answer. Alternatively, you could provide and accept your own answer. – Ron Maupin Aug 10 '17 at 3:52

In theory the TMA can be mounted near the BTS, but you risk that the signal is attenuated too much by the cable. Also most BTS have a amplifier built in, which makes a TMA mounted next to it redundant.

As the name Tower Mounted Amplifier implies, the whole point is to amplify the signal as close to the source as possible.

See http://en.wikipedia.org/wiki/Tower_Mounted_Amplifier

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Like every receiving amplifier, it is better put it near antenna. Total power budget is the same whether put it near antenna or near BTS, BUT - if you put it down it collects and amplifies noise which appears in cable. If you put it up it doesn't amplify noise from cable, so noise figure is better when receiving amplifier is near antenna. It's general principle, also applies with classic TV VHF and UHF antenna amplifiers.

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to avoid cable loss caused by feeder

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    You could improve your answer by editing it to add more details to make it more useful both for the original poster and future users. Typically short answers like this could provide more explanation about the concepts mentioned, references/links to supporting resources, or applicable examples. – YLearn May 28 '15 at 17:57

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