Most of the energy coming from a cell phone antenna is directed off to the side, angled slightly downward. Ironically, being directly under the antenna, you are probably getting a lot less RF energy beamed into your apartment than the folks who are across the street from you. Even without the roof in the way, you wouldn’t have anything to worry about.
Unless it’s a metal roof, it probably doesn’t do much to block the signals. The Verizon guy was right, but for the wrong reason. You don’t want to stand directly in front of the antenna because that’s where all of the energy is focused. Whether there’s a roof there or not, there’s nothing to worry about directly under the antenna.
Cell phone antennas are low power anyway. They have to be.
Imagine two people talking. They move farther and farther away, until they can’t hear each other very well. Now, give one person a bullhorn. It doesn’t really help, does it? Sure, it allows the other person to hear their voice, but they still can’t hear the reply, so you don’t get two-way communication.
It’s the same thing with cell phones. You can boost the transmitting power of the antenna on your roof, but it doesn’t really help you because the antenna on the roof won’t be able to hear the quiet replies from cell phones that are further away.
So what you want is for your cell phones and your roof antennas to be fairly closely matched in power. That way, they each start losing the ability to hear each other at about the same time. And, when you reach that point where they are starting to have trouble hearing each other, that’s where you put another cell antenna. That’s why you need cell phone antennas all over the place. They are very low power and only cover a small area.
Your cell phone transmits less than a watt of RF energy. Off the top of my head I don’t know what power levels they use in cell towers these days, but I’m guessing it’s somewhere around 100 watts or so. That may seem a bit like the roof antenna has the bullhorn I mentioned above, but look at the size of your cell phone’s antenna and compare that to the size of the roof antenna. The roof antenna is a lot larger, so it has much better “ears”.
To put this in perspective though, your typical broadcast FM radio station puts out about 50,000 watts. That’s why it can reach an entire city with just one antenna, where puny cell towers with their tiny power levels can only go a few blocks.
And, to put the power levels in perspective, your typical microwave oven puts out somewhere between 600 and 1200 watts, with all of that energy focused into a tiny box.
You don’t want to be directly in front of the roof antenna, or it will start to cook you. That’s why it has that 3 foot warning. Your cell phone puts out less than 1 watt, so you can put it directly up against your head and it’s no biggie.
As far as cancer dangers and the like is concerned, it’s nonexistent. Cell phone radio signals are lower in frequency than visible light, so being blasted by cell phone radiation is safer for you than being blasted by visible light radiation from something like a table lamp. Just like you don’t want to stand in front of a high powered Hollywood spotlight or it will cook you, you don’t want to stand in front of a high powered radio antenna either. And again, just like it is safe to stand underneath the Hollywood spotlight as long as you don’t go in front of it, you are safe standing under your roof’s antenna as well, for basically the same reason. Directly under it isn’t where all of the energy is going.
You don’t have anything to worry about. If you have wifi in your apartment, you are probably getting blasted by as much or more radio wave radiation from that than you are from the cell antenna on your roof.
Cell phones, cell towers, and wifi are everywhere these days. If there was really some kind of danger from it all, we’d be dropping like flies.