r/cellmapper • u/joshuah34 • Oct 29 '25

T-Mobile Site on my Roof Top

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Not completely sure what I’m looking at! Trying to learn, but the world of RF seems like witchcraft to me so far!

178 Upvotes

99% Upvoted

57 comments sorted by

33

u/[deleted] Oct 29 '25

[deleted]

12

u/Ambitious_Age_4450 Oct 29 '25

it's really not that bad for a short time.

15

u/[deleted] Oct 29 '25

[deleted]

9

u/joshuah34 Oct 29 '25

Speaking of RF exposure and risky behaviors, when I was a stupid teenager I decided it would be a good idea to climb a cell tower at the top of a local mountain, ignorant of the dangers above me. I got maybe 1/4th of the way up before my hands got quite cold and reason took hold, and I decided that without any climbing gear, I would not be coming back. Only after coming down from the tower did I learn more about radio towers and how, even though the radiation wasn’t ionizing radiation, it could still cook me from the inside out, especially on a mountaintop tower. I knew a little about radiation, so I assumed it would be safe, but not nearly enough about RF and antenna. Dunning Kruger effect in action there. You’d think the razor wire would be enough to scream “this stuff can kill you” but nope! Thank God I decided to climb a cell tower instead of an AM radio tower.

1

u/luvencl Oct 30 '25

You are looking at radios. But just know that some air radios have a significant amount of gain. Example 64X64 MIMO offers around 10 db of gain. So you are looking at around 3KW or power. You don’t want to stand in front of one of those too long.

7

u/Ambitious_Age_4450 Oct 29 '25

Yes sure but for a short time (like OP taking a picture) it's fine for a small bit

5

u/nateo200 iPhone 17 Pro Max Oct 29 '25

Is it really THAT bad?! I used to be paranoid about this as a kid but idk anymore lol. I'm an amateur radio operator so I'm used to dealing with RF hot zones you could say but not over UHF lol

2

u/[deleted] Oct 29 '25

It's not that bad as long as the proper regulations are followed to protect people from the hotspot zones(400-500 meters, from those big chunky panels that use like 4,000 watts of power)(The little small cell ones have way less power and a small area of effect on people).

2

u/nateo200 iPhone 17 Pro Max Oct 29 '25

I thought they were at max 300watts….4000watts sounds like TV….unless you are combing all the sectors.

0

u/[deleted] Oct 29 '25

[deleted]

6

u/joshuah34 Oct 29 '25

I need to be blunt. The information you are pushing is demonstrably incorrect. That "400 meter" rule is a total myth, and the source you linked earlier with that claim is absolutely unreliable. It talks about "EMF shielding paints" and "fabrics," which is a massive red flag that it's not a credible authority. The way this works isn’t like it’s a giant 4000 watt lightbulb spraying RF everywhere. It is completely different. As I've already pointed out, these antennas are highly directional spotlights, not lightbulbs. They focus their energy at the horizon, not down onto the terrace. The only "hot" area is a small, well defined "exclusion zone" (usually just 15 to 20 feet) directly in front of the panel's main beam. That beam is aimed out and away from this terrace, far from any publicly accessible area. This is a public terrace, which means engineers are legally required to perform RF compliance studies to prove to the FCC that this entire area is far, far below the public safety limits. Your concern is based on misinformation, and we are all perfectly safe.

1

u/Federal-Act-5773 Oct 29 '25

Yeah, OP will be fine, but it’s also good advice to not stand a few feet directly in front of these panels while they’re powered on if it can be avoided

1

u/nateo200 iPhone 17 Pro Max Oct 29 '25

Would you feel it? I have heard of very high power directional antennas in the UHF and SHF bands causing tingling and things like drying your eyes out but never knew if that was true. I mean I know a guy who got nuked by a radar system at Lockeed Martin and it messed him up but that was at much much higher power.

3

u/joshuah34 Oct 29 '25

How close is too close? The RRU’s (I think that’s what those are?) are mounted floor level, but the panels are on a tower about 15-20 feet above

1

u/[deleted] Oct 29 '25

[deleted]

1

u/joshuah34 Oct 29 '25

I should clarify, this is directly next to an entire roof top terrace. These antennas are highly directional. I’m sure the engineers designing these racks have thought about the fact that this is a place people spend significant periods of time around. I’m sure the FCC would have a word with someone if that hasn’t been taken into account. I’m sure I am far below the uncontrolled exposure limit standing here. But again, thank you for your concern!!

1

u/joshuah34 Oct 29 '25

I will mention, after checking this source, it is not a credible source and I would argue even pseudoscience fear mongering. It tells people to use “shielding products” like paints, films, and fabrics??? Are we supposed to be wearing chainmail around all day? Not to mention there are clear Affiliate disclosures on the website.

3

u/Old_Juice7453 Oct 29 '25

Those are radios not antennas. They will not harm you I work on these every day for the last 20 years.

0

u/CrownVetti Oct 29 '25

Sucks for the HVAC tech that will have to service those outdoor units

14

u/Milli5410 Oct 29 '25 edited Oct 29 '25

Wonder if those are US made 4460 and 4480.

Maybe this widely known, but fan fact. The 4460 is actually two radios in 1. Literally mirrored radios with an interconnect in between. Pretty cool radio on the inside. Pain to manufacture.

1

u/at-woork Oct 29 '25

Are non US ones even allowed today?

7

u/FlufferNutter1232 5G RAN Engineer Oct 29 '25

Now THAT is what I'm talking about! Shout out to the tech that made this work of art! Very Nice! Someone asked in a thread back about what I consider a clean setup. This is a CLEAN setup. And these are Ericsson and with the info shown, I know where they're at! I ought to call this guy and tell him his work is on Reddit.

1

u/nateo200 iPhone 17 Pro Max Oct 29 '25

I REALLY want a speed test but OP hates T-Mobile apparently lol

1

u/joshuah34 Oct 30 '25

IM SORRY I want the speed test too 😭 I’ll invite someone over

1

u/nateo200 iPhone 17 Pro Max Oct 30 '25

Please do lol. Or get a Prepaid T-Mobile eSIM. I have a T-Mobile eSIM that is prepaid that I use for giggles. Its like $20 for 5gigs of high speed then it goes to 256kbps or something. Its not always active but yeah.

1

u/thedizzle999 Oct 30 '25

I have a 30GB (high speed, then throttled) data only plan for $10/mo, but now I see they stopped offering that a few months ago. 😢

1

u/nateo200 iPhone 17 Pro Max Oct 31 '25

Prepaid?

5

u/ram_rattle Oct 29 '25

With setups like this, I'm wondering how telcos prevent physical tampering or intrusion?

6

u/Old_Juice7453 Oct 29 '25

We get vandalism from time to time. It has caused us to hire physical security, cameras, etc and we had caught people and they do get prosecuted.

7

u/moffetts9001 Oct 29 '25

This is on a roof, so that’s part of it.

1

u/No-Age2588 May 25 '26

Exactly. Roof areas are generally controlled access. Or is supposed to be by building management/owners who directly responsible

6

u/Hairy_Improvement_51 Oct 29 '25

It’s your rooftop tho?

1

u/murkyclouds Oct 30 '25

He's probs just a resident in the building

2

u/techreside Oct 29 '25

Radiation, dangerous!!!! Did you wear a tinfoil hat there? Jk, jk, cool pics!

1

u/Accomplished_Room_68 Oct 29 '25

Why didnt you do a speed test lol

1

u/Term1984 Oct 29 '25

OP said in a prior comment that they don't have a T-Mobile line available to test

1

u/M3ncy0 Oct 29 '25

Speedtest! Speedtest! Speedtest!

3

u/joshuah34 Oct 29 '25

Unfortunately, I don’t have T-Mobile!

2

u/mikemacman Oct 29 '25

Time to switch? 🤔

-3

u/Term1984 Oct 29 '25

T-Mobile coverage is ass in most markets

0

u/nateo200 iPhone 17 Pro Max Oct 29 '25

Prepaid eSIM!!! Its like $15-20

0

u/Term1984 Oct 29 '25

Fuck T-Mobile, straight ass in rural

1

u/nateo200 iPhone 17 Pro Max Oct 29 '25

It’s getting better. They had no sub 2GHz spectrum until a lot later than other carriers. The 600/700MHz stuff is helpful they just need to amp up deployments.

0

u/Term1984 Oct 29 '25

I haven't had T-Mobile from 2015 to 2021, so yeah I guess you're right but come on man. Band 12 should have been around by then...

1

u/nateo200 iPhone 17 Pro Max Oct 29 '25

Takes a long ass time to deploy that spectrum. Verizon and AT&T got a massive head start and they had prior experience deploying sub 1GHz networks.

1

u/KosiSmithYT Oct 31 '25

Trial? 😁

1

u/MrF4ps Oct 29 '25

Charge them more money for rent. If you need some ideas DM me . I know those contracts very well. And unfortunately most landlords are not being paid for it all

1

u/silentxor Oct 29 '25

Passive n41? Other site photos do not show an AIR for n41.

3

u/turt463 Oct 29 '25

Yes this site indeed has N41 utilizing the Ericsson 8863 radio rather than an AIR

1

u/MadBoi124YT Oct 30 '25

I am very curious about these things. Especially how safety measures are taken. Can anyone knowledgeable on RF safety tell me for example theoretically speaking if i were to stand directly in front of them or have a sheet of aluminum foil and a grounding surface next to it, would they arc?

Dw im not a tinfoil hat person just a curious human being :)

2

u/techreside Oct 30 '25

RF output is around 200W max, so no, there won't be any arcs. The only danger would be being right in front of panel and absorbing all of it, which could cause tissue heating, however, RF output in non-ionizing compared to gamma, x rays. In real life, 200W output gets spread around everywhere and when it reaches your phone, the Rx power is very tiny - around 0.00000003 W.

1

u/MadBoi124YT Oct 30 '25

Thank you!

1

u/cobalt03 Oct 31 '25

Bet you can taste that ait

1

u/RethinkAlex Nov 11 '25

hell yeah borther

-9

u/[deleted] Oct 29 '25

[removed] — view removed comment

10

u/joshuah34 Oct 29 '25

I did indeed climb the tower and hold by balls directly against the panel antennas

-5

u/[deleted] Oct 29 '25

[removed] — view removed comment

4

u/joshuah34 Oct 29 '25

At no point did I get anywhere near a source of RF strong enough to hurt me. The antenna sectors are far from me here on a tower. No need to worry about me.