Birds on a Cell Site

I saw several birds happily sitting on a cell phone tower yesterday. They
were sitting right on the antenna panels! Why didn't they fry and fall-over
dead? Don't these cell phone panels radiate about 100 watts of power?

"Mij Adyaw" <mij@TheBitBucket.com> wrote in message news:7bIIg.2002$AP2.1143@fed1read10...
>I saw several birds happily sitting on a cell phone tower yesterday. They
> were sitting right on the antenna panels! Why didn't they fry and fall-over
> dead? Don't these cell phone panels radiate about 100 watts of power?
>

Birds evolving radiation resistance?
Darwin vindicated! :-)

"Mij Adyaw" <mij@TheBitBucket.com> wrote in
news:7bIIg.2002$AP2.1143@fed1read10:

> I saw several birds happily sitting on a cell phone tower yesterday.
> They were sitting right on the antenna panels! Why didn't they fry and
> fall-over dead? Don't these cell phone panels radiate about 100 watts
> of power?
>
>

Why? It seems to me(not knowing) that they wouldn't need much more than a
given Cell phone outputs. I mean, if a Cell phone uses anywhere from .06
to .6 watts of power to contact a given Cell tower, why would that tower
need more than that to transmit to that given Cell phone? I wonder. Each of
them only needs to reach out around 4 or 5 miles at the most, don't they?

still learning
buck

I have read in this newsgroup that cell towers radiate about 100 watts. Is
this correct?

"buck rojerz" <inorbit@outerspace.org> wrote in message
news:Xns98303B1B03A41ou812@216.168.3.44...
> "Mij Adyaw" <mij@TheBitBucket.com> wrote in
> news:7bIIg.2002$AP2.1143@fed1read10:
>
>> I saw several birds happily sitting on a cell phone tower yesterday.
>> They were sitting right on the antenna panels! Why didn't they fry and
>> fall-over dead? Don't these cell phone panels radiate about 100 watts
>> of power?
>>
>>
>
> Why? It seems to me(not knowing) that they wouldn't need much more than a
> given Cell phone outputs. I mean, if a Cell phone uses anywhere from .06
> to .6 watts of power to contact a given Cell tower, why would that tower
> need more than that to transmit to that given Cell phone? I wonder. Each
> of
> them only needs to reach out around 4 or 5 miles at the most, don't they?
>
> still learning
> buck

>>> I saw several birds happily sitting on a cell phone tower yesterday.
>>> They were sitting right on the antenna panels! Why didn't they fry and
>>> fall-over dead? Don't these cell phone panels radiate about 100 watts
>>> of power?

I believe it's more like 40W, so you might as well think of it as a bird
sitting very close to a 40W light bulb: That's a small enough power source
that they'll probably feel themselves getting hot (and move!) well before they
"fry." This also assumes birbs absorb heat well at cell phone frequencies,
although this is probably a good assumption.

Pager towers used considerably more power (a couple hundred watts), if I'm
remembering correctly.

>> Why? It seems to me(not knowing) that they wouldn't need much more than a
>> given Cell phone outputs. I mean, if a Cell phone uses anywhere from .06
>> to .6 watts of power to contact a given Cell tower, why would that tower
>> need more than that to transmit to that given Cell phone?

Cell towers transmit far more power than cell phones transmit because the
phone is at a distinct disadvantage when trying to *receive* that signal: They
only have one, small antenna. (Whereas, when the tower has to receive from
the handset, it has *multiple* *large* antennas to do so with.) Hence, as the
tower isn't particularly power constrained, it uses additional transmission
power to make up for the poorer receive abilities of the handset.

---Joel Kolstad

Transmitter power is more likely 10-20W per carrier into one of three 12
dBi sector antennas. This amounts to soumething on the order of 300-400
watts effective radiated power(ERP).

However, the antenna gain which produces the 12 dBi sector pattern
actually means that the 20 watts coming out is spread over a larger,
rather than a smaller (dipole sized or 1.5 by 3 inches at 1900 MHz).
This means that even a bird sitting on the antenna, is potentially
intercepting a much smaller fraction (12 dB would be about a factor of
1/16 ) that it would have seen with a lower gain antenna.

Even if the bird managed to absorb the maximum possible, it wouldn't
be enough power (1 watt territory) to do much. While there might be
several carriers on the one sector antenna, the bird doesn't absorb all
the power and ismore in danger of being seen and eaten by a hawk than
getting injured by RF.

The cell transmitters run more power than handsets because for voice
calls, they are serving ~60 or so users and for data calls, they have to
get more signal to the handset in order to be able to deliver higher
data rates in the voice-only coverage area. For a loaded CDMA carrier,
the base power could be as low as 20/60 = .33 watts which is about the
same as the handset would max out at. This makes sense since for a
voice call, the 10 kbps data to support voice has to be fully
bi-directional. For a data call, most systems are assymetric and offer,
for example, 600 kbps down and 100 kbps up.

g

>>>> I saw several birds happily sitting on a cell phone tower yesterday.
>>>> They were sitting right on the antenna panels! Why didn't they fry and
>>>> fall-over dead? Don't these cell phone panels radiate about 100 watts
>>>> of power?
>
> I believe it's more like 40W, so you might as well think of it as a bird
> sitting very close to a 40W light bulb: That's a small enough power source
> that they'll probably feel themselves getting hot (and move!) well before they
> "fry." This also assumes birbs absorb heat well at cell phone frequencies,
> although this is probably a good assumption.
>
> Pager towers used considerably more power (a couple hundred watts), if I'm
> remembering correctly.
>
>>> Why? It seems to me(not knowing) that they wouldn't need much more than a
>>> given Cell phone outputs. I mean, if a Cell phone uses anywhere from .06
>>> to .6 watts of power to contact a given Cell tower, why would that tower
>>> need more than that to transmit to that given Cell phone?
>
> Cell towers transmit far more power than cell phones transmit because the
> phone is at a distinct disadvantage when trying to *receive* that signal: They
> only have one, small antenna. (Whereas, when the tower has to receive from
> the handset, it has *multiple* *large* antennas to do so with.) Hence, as the
> tower isn't particularly power constrained, it uses additional transmission
> power to make up for the poorer receive abilities of the handset.

>

"g" <wh@t.me.worry> wrote in message
news:44f73bbd$0$34524$742ec2ed@news.sonic.net...
> Transmitter power is more likely 10-20W per carrier into one of three 12
> dBi sector antennas. This amounts to soumething on the order of 300-400
> watts effective radiated power(ERP).
>
<...> Even if the bird managed to absorb the maximum possible, it
wouldn't
> be enough power (1 watt territory) to do much. While there might be
> several carriers on the one sector antenna, the bird doesn't absorb all
> the power and ismore in danger of being seen and eaten by a hawk than
> getting injured by RF.
<Snip>

I think you have solved the problem of dropped calls. All this time people
thought it was poor technology, not birds blocking/absorbing the signal;

hence the phrase "bird droppings"!

In alt.cellular.sprintpcs Mij Adyaw <mij@thebitbucket.com> wrote:
> I saw several birds happily sitting on a cell phone tower yesterday. They
> were sitting right on the antenna panels! Why didn't they fry and fall-over
> dead? Don't these cell phone panels radiate about 100 watts of power?
>

Unless all 100 watts are absorbed by a single bird, I doubt you will kill it
.... it will probably just pant to cool itself ;-)

Much of the energy will bounce right off of the bird, and that which is
absorbed will only be a few watts ... much less than what you would ever feel
when you step out into the sunshine. You do realize that people have been
climbing fully energized transmission towers for years? FM radio broadcasts
at 100,000 watts! In that case, it is probably best not to wear a watch, or
smile if you have braces ;-) BTW ... I have never seen any birds dropping
around FM or TV antennas either.

--
Thomas T. Veldhouse
Key Fingerprint: 2DB9 813F F510 82C2 E1AE 34D0 D69D 1EDC D5EC AED1

"Thomas T. Veldhouse" <veldy71@yahoo.com> wrote in message
news:ddHJg.1434$Yy1.921@textfe.usenetserver.com...
> In alt.cellular.sprintpcs Mij Adyaw <mij@thebitbucket.com> wrote:
>> I saw several birds happily sitting on a cell phone tower yesterday. They
>> were sitting right on the antenna panels! Why didn't they fry and
>> fall-over
>> dead? Don't these cell phone panels radiate about 100 watts of power?
>>
>
> Unless all 100 watts are absorbed by a single bird, I doubt you will kill
> it
> ... it will probably just pant to cool itself ;-)

I seem to remember a caution by Wilson electronics about positioning the
yaggi antenna close to where children would be playing or people would be
located for extended periods of time when I was looking into the cellular
repeater.

Were they being overly cautious?

EOO wrote:
>
> "Thomas T. Veldhouse" <veldy71@yahoo.com> wrote in message
> news:ddHJg.1434$Yy1.921@textfe.usenetserver.com...
> > In alt.cellular.sprintpcs Mij Adyaw <mij@thebitbucket.com> wrote:
> >> I saw several birds happily sitting on a cell phone tower yesterday. They
> >> were sitting right on the antenna panels! Why didn't they fry and
> >> fall-over
> >> dead? Don't these cell phone panels radiate about 100 watts of power?
> >>
> >
> > Unless all 100 watts are absorbed by a single bird, I doubt you will kill
> > it
> > ... it will probably just pant to cool itself ;-)
>
> I seem to remember a caution by Wilson electronics about positioning the
> yaggi antenna close to where children would be playing or people would be
> located for extended periods of time when I was looking into the cellular
> repeater.
>
> Were they being overly cautious?

Impalement.

Notan