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627 online
Server Time:
2024-05-12 09:04:20
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 Fubster
  
Location: Tampa Bay Area, Florida
Gender: Male
Though highly intelligent, guide dogs cannot interpret street signs.
 |  |  |  | Re: RF Towers, and Roof Tops
<Reply # 20 on 6/23/2005 11:31 PM >
|  | | | INCOMING TRANSMISSION
I was staying at a hotel in Boston about a week ago, and I got onto the roof. On the roof was some sort of antennae, and a sign warning of RF exposure. I decided not to risk it, but I still got a headache. That is all.
END TRANSMISSION
Sometimes, you need to march right in and demand your rights, even if you don't know what your rights are, or who it is you're talking to. Then, on your way out, slam the door. |
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Explorer Zero
    
| | | Re: RF Towers, and Roof Tops
<Reply # 21 on 6/24/2005 1:39 AM >
| | | | here is one I cant ID but see a lot some sort of network maybe telecom
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PoT.
Location: Vancouver Area, BC
Gender: Male
What? I'm not supposed to be here?
| | Re: RF Towers, and Roof Tops
<Reply # 22 on 6/24/2005 2:01 AM >
| | | | Posted by 2Xtreme
here is one I cant ID but see a lot some sort of network maybe telecom
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Appears to be a microwave line of sight array. Communications companies use them frequently rather than spend the expense of laying cable or fiber.
Cheers!
-PoT
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ArmchairExplorer
Location: Vancouver
| | Re: RF Towers, and Roof Tops
<Reply # 23 on 6/24/2005 4:02 AM >
| | | | Posted by drainpunk
Sh*t.. Gotta be extra careful.. Approaching from the direction they are not pointing is safe(r)..?
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Yes, it's safer to approach a directional antenna from behind. I'm not prepared to put anyone's health (including my own) on the line by estimating a danger radius. Safety ranges will vary considerably depending on the type of transmitter. One could get a lot closer to the back of a terrestrial microwave link than a Pave Paws early warning radar, for instance.
My inclination is to honor barriers around RF isntallations to the same degree as barriers around high voltage electrical equipment. RF can be at least as dangerous as high voltage and both risks should be treated with similar respect.
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rz350
This member has been banned. See the banlist for more information.
Location: toronto
Gender: Male
The looniest, zaniest, spontaneous, sporadic Impulsive thinker, compulsive drinker, addict
| | Re: RF Towers, and Roof Tops
<Reply # 24 on 6/24/2005 4:27 AM >
| | | | IM going to say just avoid Dish and Horn antennas all together from the front. The focused beam off of them can pack alot of power into a small area (not a good thing at all)_ that and since horn antennas tend to be used in the microwave freqs the RF heating should be quite pronounced.
ducky 999 |
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ArmchairExplorer
Location: Vancouver
| | Re: RF Towers, and Roof Tops
<Reply # 25 on 6/25/2005 7:06 AM >
| | | | Another type of antenna to add to the collection:
This is a phased array. They are most commonly used in government and military radar applications but will likely become more prevalent for commercial use as time goes on. Phased arrays are steerable directional antennas mounted on a flat plane. Unlike dishes, the beam from a phased array could be pointing in any (forward) direction from the array: if you can see the array, it could be directing a beam right at you.
With regard to approaching any kind of directional antenna from the rear, the safety issue is with the beam sidelobes. While a directional antenna kicks most of the transmitter power forwards, a fair bit of energy leaks into sidelobes at the rear and sides of the antenna. If the main beam is strong enough to, e.g. cause blindness or otherwise ruin your life, the sidelobes could pack enough punch to ruin your day.
Here is an overview of the sidelobe topology of two antennas located at the same position. One transmitter's footprint is shown in red while the other is shown in blue. Areas of mutual coverrage are violet.
The longer ellipses are the main beams while the smaller ellipses are the beam sidelobes.
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Roadwolf
  
The Wolf!
Location: Buffalo, NY (formerly Toronto, Canada)
Gender: Male
Living on the Road and Rails.
| |  | | Re: RF Towers, and Roof Tops
<Reply # 26 on 6/29/2005 5:40 PM >
| | | | indeed...
i didn't bother getting too much into how directional arrays work, and lobes and all - I was just writing a general info guide... but yea, thanks for that info Armchair. 
its very useful.
smart advice, if you see anything that looks like a dish, or radar, stay away !
Add me on Skype or Steam: Roadwolf611
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drainpunk
| | Re: RF Towers, and Roof Tops
<Reply # 27 on 6/29/2005 11:58 PM >
| | | | | smart advice, if you see anything that looks like a dish, or radar, stay away ! |
Yeah.. Too bad the best spots often have dishes.. GRRRH.
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Citizen
Location: Melbourne, Australia
Gender: Male
| | Re: RF Towers, and Roof Tops
<Reply # 28 on 7/1/2005 4:49 AM >
| | | | Posted by Robz
just an extra safety note...never go inside base buildings or surrounding buildings that house these dishes...as you will suffer a horrible death if its turned on, and if you do go into one, make sure you have one of the fuses/switches/ other name that i cant remember, with you to make sure it cant be turned on with you inside
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Do similar risks apply to the equipment rooms of cellular base-stations? (Both in terms of high voltage and the presence of RF fields...)
The network types I'm concerned about are those that exist here in Australia, so GSM900, GSM1800 (<= most common types) CDMA800 and 3G/UTMS which broadcasts at around 1.9-2.1Ghz and often/always has a ~22Ghz uplink, presumably to the switching centre.
The problem with mobile comms in Oz is that there are four independent, competing, nation-wide networks, plus a few smaller, city-based networks, wholesalers, places I've never heard of, etc. All of which means that base stations are everywhere. I don't think there's a single office block, hospital or shopping centre anywhere in the country that doesn't have a nest of dipoles on the roof, so of course, I can't set foot on them anymore  .
The reason I'm worried about the equipment rooms is that the upper mechanical floor of many office buildings I've seen end up being given over to housing all the transmitters and other equipment for these rooftop arrays. I've gone inside a few, but never stay for more than, say, 30 seconds before I get nervous of near-microwave exposure and bail. Am I just being paranoid?
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Roadwolf
The Wolf!
Location: Buffalo, NY (formerly Toronto, Canada)
Gender: Male
Living on the Road and Rails.
| | | | Re: RF Towers, and Roof Tops
<Reply # 29 on 7/18/2005 3:53 PM >
| | | | Personally, I work in equipment rooms such as this on a daily basis, and I wouldnt be concerned about going in there... however I have no clue if I am sterile or not as I have never actually tried to have a kid yet... so.. I don't know if it has effected me that way.
Add me on Skype or Steam: Roadwolf611
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The Bean
Location: Austin TX
Gender: Male
Some dude with a camera
| | | Re: RF Towers, and Roof Tops
<Reply # 30 on 7/18/2005 7:45 PM >
| | | | For what it's worth..
There's a cell tower (CDMA I believe) within 10 feet of the place I used to work at, and the equipment was placed against the back wall of the building. So everyone routinely passes within 2-3 feet of it every time they go into the cooler or the shitter.
I really don't think there's much risk of going near the equipment for digital cell towers, as long as you stay away from the cabling. The cables are well shielded, but I would assume there's some serious power going through them.
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cpkangaroo
Location: Longmont, CO
Gender: Male
| | | Re: RF Towers, and Roof Tops
<Reply # 31 on 10/25/2005 1:11 PM >
| | | | Posted by ArmchairExplorer
Here is an overview of the sidelobe topology of two antennas located at the same position. One transmitter's footprint is shown in red while the other is shown in blue. Areas of mutual coverrage are violet.
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A completely useless post. But I just realized I'm currently sitting in the violet area. My office is like three blocks from those antennas. 
Buy heroin, it's good! |
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SteamPunk
Location: Sailing the seas of sleaze.
| | Re: RF Towers, and Roof Tops
<Reply # 32 on 10/25/2005 7:03 PM >
|  | | | RF=Bad for you!!
Freebanding is the somewatt foolish art of playing with RF in the 11 meter band, (CB, although it is a good HF band), with high wattages. Check out www.Bigradios.com ,(look at the keydown vidios!) It is doubtful I'll ever be able to have kidlets, and I'll probably die of cancer of something, but it sure is fun!! Think about how much RF is flying through your head, body right now. How much RF is flying around your town/city right now!! Just to show ya'll watt RF can do!
BREAK OUT THE TINFOIL HAT'S FOLKS!!!
[last edit 10/25/2005 7:08 PM by SteamPunk - edited 1 times]
I used to be with it, but then they changed what it was. Now what I'm with isn't it, and what's it seems weird and scary to me, and it'll happen to you, too! |
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