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UER Forum > Archived Rookie Forum > Rooftop antenna safety (Viewed 994 times)
Klausius 






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Rooftop antenna safety
< on 8/17/2013 6:35 PM >
Posted on Forum: UER Forum
 
I found an open roof hatch on a local newspaper office building, but as a media building there were several drum shaped antennas which frightened me off as I did not knew what kind and power output they had. No huge sky pointing dishes though.

There was no radiation warning sign anywhere, and it seemed like the only way to access the roof (for people supposed to be there). Safety regulations require these even for non public places, if anybody might be present in the area.

I tried finding some data about minimum safety distance and radiation exposure of this antenna kind as they are very common to rooftops in the vicinity.
Now the uer.ca reference entry in the archive seems to be http://www.uer.ca/...urrpage=1&pp#post0
In there anything concerning microwave stuff is supposed to be very dangerous and keep away. The same applies to a few other posts concerning microwave antennas, not discerning between the antennas pointing to the sky and the ones pointing obviously just right over ground level.

But after googling around a bit I found some FCC data and german workplace safety documentation, both outlining that the drum type antennas are very low power and anything else besides standing right in front and very close is harmless.
http://transition....y/rf-faqs.html#Q19

How do other people handle this kind of antenna on a rooftop? Just keep to the back side of the drum and enjoy the view? Bad experiences?

Evilbunny 


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Re: Rooftop antenna safety
<Reply # 1 on 8/17/2013 6:37 PM >
Posted on Forum: UER Forum
 
I have never had any but I know what rf burns are like. I would never go near one inless I see a cut cable. You can't feel these while its happening not good. I have heard of as little as 5 watts making a finger nail come off. And those roof mounted antennas are usually hundreds of watts. if not thousands
[last edit 8/17/2013 6:44 PM by Evilbunny - edited 1 times]

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Crypton 


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Re: Rooftop antenna safety
<Reply # 2 on 8/17/2013 7:11 PM >
Posted on Forum: UER Forum
 
The drum shaped antennas you encountered are point to point microwave transceivers. Weird that there were no signs posted to indicate at which point RF exposure exceeds minimum safety baseline or background. Best advice is not to stand in front of. There is typically some leakage around the back, but at a much lower ratio. Just don't hang around for too long.

Klausius 






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Re: Rooftop antenna safety
<Reply # 3 on 8/17/2013 9:25 PM >
Posted on Forum: UER Forum
 
Crypton is right, they look like point to point microwave link antennas
http://onegigabit....ntenna_540x447.jpg

Evilbunny is there a source for that hundreds of watts number? I thought these to be very focused and not requiring that much power. I've come across GSM antennas on rooftops, these were clearly signed as 'keep away, unsafe radiation' and are obviously intended to spread out their signals, but these drums were totally unsigned. I wouldn't think about standing in front of them, somebody would at least notice the dropped signal on a sunny day.

Evilbunny 


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Re: Rooftop antenna safety
<Reply # 4 on 8/18/2013 4:42 AM >
Posted on Forum: UER Forum
 
Posted by Klausius
Crypton is right, they look like point to point microwave link antennas
http://onegigabit....ntenna_540x447.jpg

Evilbunny is there a source for that hundreds of watts number? I thought these to be very focused and not requiring that much power. I've come across GSM antennas on rooftops, these were clearly signed as 'keep away, unsafe radiation' and are obviously intended to spread out their signals, but these drums were totally unsigned. I wouldn't think about standing in front of them, somebody would at least notice the dropped signal on a sunny day.
It depends what their being used for as a ham radio operator can transmit on microwave not many do but they still can and they can transmit from 1 watt up to 1500watts but if it was something more important It would be much higher maximum I believe not all of them are required to have signs not sure on that though. Microwave has so many uses that require different things I can't be 100% on the wattage needs but I doubt it is less than 80-100watts

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TeePER 


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Re: Rooftop antenna safety
<Reply # 5 on 8/20/2013 5:37 PM >
Posted on Forum: UER Forum
 
Posted by Evilbunny
... little as 5 watts making a finger nail come off.


5 watts? I dont think you can do much damage with 5W.

source: Just stuck finger in a transmitting 5w portable
[last edit 8/20/2013 8:58 PM by TeePER - edited 1 times]

Evilbunny 


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Re: Rooftop antenna safety
<Reply # 6 on 8/21/2013 1:03 AM >
Posted on Forum: UER Forum
 
Posted by TeePER


5 watts? I dont think you can do much damage with 5W.

source: Just stuck finger in a transmitting 5w portable


I have no clue about that I read it on a ham forum.

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Crypton 


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Re: Rooftop antenna safety
<Reply # 7 on 8/21/2013 5:27 AM >
Posted on Forum: UER Forum
 
Posted by Evilbunny


I have no clue about that I read it on a ham forum.


You should not be regurgitating information you know nothing about, especially giving advice to someone on that information. At least you did not tell him that climbing AM tower was easy as cake.

/-/ooligan 


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Re: Rooftop antenna safety
<Reply # 8 on 8/23/2013 7:28 AM >
Posted on Forum: UER Forum
 
Wow, what a lot of BS!

"As a ham radio operator..." you are clueless about microwave links.

Some microwave "cans" may be for receive only, but unless you know that, just avoid them all within reason.

Biologic damage due to intense radio frequency/non-ionizing radiation depends on a lot of factors -- the tissue being exposed, length of exposure, intensity of the field (which depends more on distance from the emitter, antenna beam focus & it's effective radiated power than it does on pure wattage), and frequency. The Radio Frequency is the factor that makes it OK for our ham radio pal to stick his VHF radio antenna up his ass while transmitting all day at 5 watts power output, yet holding a handheld PCS cellphone (putting out less than a watt transmit power) up to your head for a couple hours each day or cop in close proximity to an X, K or Ka-band traffic radar antenna are definitely frowned-upon as being a health hazard.

The MW antennas on the newspaper office may be a link between the offices & the printing plant(s) -- they use the MW circuit to send the media to the plant that will then print it, etc. Yes, most MW circuits use very little RF power (like a watt or less), relying on a clear line of site path, high-gain antennas on both ends, and very sensitive receivers, digital signal processing, minimizing terrestrial interference by using circular polarization, etc.


The best answer anyone can offer is to stay as far away as reasonably possible from them, though yes, you're "probably" safe if you're at least 10 or 15' away from the front of the antennas. Sometimes it is possible that if you have a piece of metal similar in length to the radio wavelength of the signal, that metal item (such as a pen) may absorb & resonate some of that radio frequency energy & heat up. I knew a few military comms guys that would cook hot dogs in the field by putting a certain length of coat hangar or straightened paper-clip into a hot dog & then using a piece of wood to hold that hot dog up in front of a troposcatter antenna.


Just stay away from pretty much any antenna that may be transmitting. Also stay away from the jackasses that response to a vague question about RF with very specific instructions, especially if it boils down to "Don't worry about it," and ignore anyone that starts their RF treatise with "As a ham radio operator" -- most hams, and definitely the one who already replied here, are clueless but they think that just because they got their ham license, they're RF engineers. I think TeePer's amateur radio callsign might be KB0ZO.


/-/ooligan

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Evilbunny 


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Re: Rooftop antenna safety
<Reply # 9 on 8/23/2013 8:05 AM >
Posted on Forum: UER Forum
 
Posted by /-/ooligan
Wow, what a lot of BS!

"As a ham radio operator..." you are clueless about microwave links.

Some microwave "cans" may be for receive only, but unless you know that, just avoid them all within reason.

Biologic damage due to intense radio frequency/non-ionizing radiation depends on a lot of factors -- the tissue being exposed, length of exposure, intensity of the field (which depends more on distance from the emitter, antenna beam focus & it's effective radiated power than it does on pure wattage), and frequency. The Radio Frequency is the factor that makes it OK for our ham radio pal to stick his VHF radio antenna up his ass while transmitting all day at 5 watts power output, yet holding a handheld PCS cellphone (putting out less than a watt transmit power) up to your head for a couple hours each day or cop in close proximity to an X, K or Ka-band traffic radar antenna are definitely frowned-upon as being a health hazard.

The MW antennas on the newspaper office may be a link between the offices & the printing plant(s) -- they use the MW circuit to send the media to the plant that will then print it, etc. Yes, most MW circuits use very little RF power (like a watt or less), relying on a clear line of site path, high-gain antennas on both ends, and very sensitive receivers, digital signal processing, minimizing terrestrial interference by using circular polarization, etc.


The best answer anyone can offer is to stay as far away as reasonably possible from them, though yes, you're "probably" safe if you're at least 10 or 15' away from the front of the antennas. Sometimes it is possible that if you have a piece of metal similar in length to the radio wavelength of the signal, that metal item (such as a pen) may absorb & resonate some of that radio frequency energy & heat up. I knew a few military comms guys that would cook hot dogs in the field by putting a certain length of coat hangar or straightened paper-clip into a hot dog & then using a piece of wood to hold that hot dog up in front of a troposcatter antenna.


Just stay away from pretty much any antenna that may be transmitting. Also stay away from the jackasses that response to a vague question about RF with very specific instructions, especially if it boils down to "Don't worry about it," and ignore anyone that starts their RF treatise with "As a ham radio operator" -- most hams, and definitely the one who already replied here, are clueless but they think that just because they got their ham license, they're RF engineers. I think TeePer's amateur radio callsign might be KB0ZO.


/-/ooligan

As I know you are replying to me I never said I was a ham radio operator I was trying to help. And that is a dick move putting someones callsign up.


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Crypton 


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Re: Rooftop antenna safety
<Reply # 10 on 8/23/2013 2:41 PM >
Posted on Forum: UER Forum
 
Posted by /-/ooligan
[redacted]

/-/ooligan


If I could donate to you, I would

Post by Evilbunny
As I know you are replying to me I never said I was a ham radio operator I was trying to help. And that is a dick move putting someones callsign up.


Callsigns are public.

Pravus 


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Re: Rooftop antenna safety
<Reply # 11 on 9/8/2013 10:41 PM >
Posted on Forum: UER Forum
 
I used to work on cell towers, and even though it was osha "law" that the site had to be shut down entirely while people were on a tower it never happened.. "Generally" most of the ones that look like a dish or are big rectangular boxes are pretty directional.. One job we had to change out the mounts on an active array on a rooftop, I don't recall any RF warning signs anywhere up there, but I kinda ignored them at that point.. For the most part you should be generally safe if you stay behind them (the side that the mounts are on) you should likely be safe if you are next to many of them as well, but unless you have to be there really isn't any reason to do so.. Also if they are on a rooftop I somewhat doubt (not fact, just opinion) they won't have the antennas beaming across the roof when they could just put it on the other side or in a place where someone is less likely to get fried and limit their liability from someone wandering up there to do maintenance on the roof.. Just my 2 cents on the subject..

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UER Forum > Archived Rookie Forum > Rooftop antenna safety (Viewed 994 times)



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