P
Piglet
Guest
On 09/06/2019 08:15, Jan Panteltje wrote:
Why are you worried by 2.4GHz?
piglet
Why are you worried by 2.4GHz?
piglet
J
Jan Panteltje
Guest
On a sunny day (Sun, 9 Jun 2019 10:33:42 +0100) it happened Piglet
<erichpwagner@hotmail.com> wrote in <qdijpl$cgl$1@dont-email.me>:
It is close to the same frequency that heats stuff in your microwave.
<erichpwagner@hotmail.com> wrote in <qdijpl$cgl$1@dont-email.me>:
It is close to the same frequency that heats stuff in your microwave.
J
Jan Panteltje
Guest
On a sunny day (Sun, 09 Jun 2019 11:55:21 +0300) it happened
upsidedown@downunder.com wrote in
<aghpfe17ecgbss0arvffh4921kqnksnu60@4ax.com>:
Come on ;-)
I a did hang out one level lower for almost an hour without problems
before going up to the dishes.
Yes, and beaming 2.4 GHz up to oscar 100 I have about 75 Watts max available,
will be experimenting with several feeds.
It is circular polarized so will also try to point a helical
at the offset dish, large part of it goes past the dish ..
Many different waveguide types possible, This is a nice site:
https://rfantennas.wordpress.com/author/hb9pzk/
No space for a large prime focus dish here, wind load would blow it away anyways.
Now when weather gets better an some much needed parts coming in, i tis more fun.
Just put the garden furniture back in place, some blew away in the storm yesterday.
Even the sun shines here today ...
Coming week rain rain rain predicted.. that is good weather to test that coil project stuff.
upsidedown@downunder.com wrote in
<aghpfe17ecgbss0arvffh4921kqnksnu60@4ax.com>:
Come on ;-)
I a did hang out one level lower for almost an hour without problems
before going up to the dishes.
Anyway, why would a metallic paraboloid have any significant back
lobe?
The interesting thing is that people seem to be more afraid the larger
the dish is. With constant transmitter power, the larger the dish, the
lower the near filed power density. Admittedly, the near field
extends a few wavelengths further out. The most dangerous part of a
big dish antenna is the feedhorn at the focal point. Never look into
the waveguide, unless you are absolutely sure (remove mains fuses
that there are no RF-power or you might loose your sight.
Yes, and beaming 2.4 GHz up to oscar 100 I have about 75 Watts max available,
will be experimenting with several feeds.
It is circular polarized so will also try to point a helical
at the offset dish, large part of it goes past the dish ..
Many different waveguide types possible, This is a nice site:
https://rfantennas.wordpress.com/author/hb9pzk/
No space for a large prime focus dish here, wind load would blow it away anyways.
Now when weather gets better an some much needed parts coming in, i tis more fun.
Just put the garden furniture back in place, some blew away in the storm yesterday.
Even the sun shines here today ...
Coming week rain rain rain predicted.. that is good weather to test that coil project stuff.
P
Piglet
Guest
On 09/06/2019 11:26, Jan Panteltje wrote:
It is more the power that causes the heating than hitting the "right
frequency". Industrial microwave ovens use other frequencies too. I'd be
just as worried being near 800W at L or C band.
<https://en.wikipedia.org/wiki/Electromagnetic_absorption_by_water#/media/File
ielectric_loss_water.png>
piglet
It is more the power that causes the heating than hitting the "right
frequency". Industrial microwave ovens use other frequencies too. I'd be
just as worried being near 800W at L or C band.
<https://en.wikipedia.org/wiki/Electromagnetic_absorption_by_water#/media/File
ielectric_loss_water.png>piglet
Guest
On Saturday, June 8, 2019 at 12:37:56 PM UTC-4, Banders wrote:
The tower may get taller or perhaps turn into multiple units. So the terms should be subject to re-negotiation with changes to the tower(s). What about an access route? Will the phone company take care of the taxes for the tower? Talk with a realtor about how this will affect your property value and desireability in future markets.
The tower may get taller or perhaps turn into multiple units. So the terms should be subject to re-negotiation with changes to the tower(s). What about an access route? Will the phone company take care of the taxes for the tower? Talk with a realtor about how this will affect your property value and desireability in future markets.
M
mpm
Guest
On Sunday, June 9, 2019 at 6:44:21 AM UTC-4, piglet wrote:
Um... microwave ovens have a lot higher peak power, and the energy is concentrated into a cavity. Not exactly the same thing as an outdoor cell site. Plus, the distances involved from emitter to absorber are magnitudes apart in these two scenarios. Again, non-issue.
Microwave ovens typically operate on ISM band frequencies (FCC Rules Part-18).
On 09/06/2019 11:26, Jan Panteltje wrote:
On a sunny day (Sun, 9 Jun 2019 10:33:42 +0100) it happened Piglet
wrote in >:
On 09/06/2019 08:15, Jan Panteltje wrote:
That does not bother me, but anything near 2.4 GHz you better watch out for.
Why are you worried by 2.4GHz?
piglet
It is close to the same frequency that heats stuff in your microwave.
It is more the power that causes the heating than hitting the "right
frequency". Industrial microwave ovens use other frequencies too. I'd be
just as worried being near 800W at L or C band.
https://en.wikipedia.org/wiki/Electromagnetic_absorption_by_water#/media/File
piglet
Um... microwave ovens have a lot higher peak power, and the energy is concentrated into a cavity. Not exactly the same thing as an outdoor cell site. Plus, the distances involved from emitter to absorber are magnitudes apart in these two scenarios. Again, non-issue.
Microwave ovens typically operate on ISM band frequencies (FCC Rules Part-18).
M
mpm
Guest
On Sunday, June 9, 2019 at 6:44:21 AM UTC-4, piglet wrote:
Actually, it's more about resonance.
The average adult human body is a reasonably good RF absorber at frequencies about 80 to 100 MHz. And nothing beats resonance, and proximity, for good power transfer!
So keep your distance from 100 kW ERP FM broadcast antenna arrays.
And even then, the safe distance is something on the order of 20-feet under the typical antenna for occupational exposure.
Short towers with high-power broadcast (FM & TV), with homes built nearby, are a legitimate concern for RF exposure (although the vast majority are fine). But it's rare (I've never heard of a legitimate case) involving a monopole & cellular / PCS configuration being a problem. Other than a hyped-up, baseless one, that is. It's a non-issue.
Actually, it's more about resonance.
The average adult human body is a reasonably good RF absorber at frequencies about 80 to 100 MHz. And nothing beats resonance, and proximity, for good power transfer!
So keep your distance from 100 kW ERP FM broadcast antenna arrays.
And even then, the safe distance is something on the order of 20-feet under the typical antenna for occupational exposure.
Short towers with high-power broadcast (FM & TV), with homes built nearby, are a legitimate concern for RF exposure (although the vast majority are fine). But it's rare (I've never heard of a legitimate case) involving a monopole & cellular / PCS configuration being a problem. Other than a hyped-up, baseless one, that is. It's a non-issue.
M
mpm
Guest
On Sunday, June 9, 2019 at 2:56:37 AM UTC-4, upsid...@downunder.com wrote:
With all due respect, these two statements demonstrate a fundamental misunderstanding of how modern-day LTE networks operate in the downlink.
With all due respect, these two statements demonstrate a fundamental misunderstanding of how modern-day LTE networks operate in the downlink.
M
mpm
Guest
On Sunday, June 9, 2019 at 2:56:37 AM UTC-4, upsid...@downunder.com wrote:
None of this radiation exposure stuff matters.
In the United States, FCC Licensee, including AT&T and all the other carriers, are REQUIRED BY LAW to protect the public from the potential effects of human exposure to non-ionizing RF radiation.
Furthermore, the carriers have risk management departments in place that would make sure the public is never exposed beyond what the regulations mandate.
And at these frequencies, you'd basically have to climb the tower and hug the antenna to exceed the occupational exposure limits. It's a non-issue for wireless towers. Broadcast FM & TV, and high-power radar/microwave are another story.
None of this radiation exposure stuff matters.
In the United States, FCC Licensee, including AT&T and all the other carriers, are REQUIRED BY LAW to protect the public from the potential effects of human exposure to non-ionizing RF radiation.
Furthermore, the carriers have risk management departments in place that would make sure the public is never exposed beyond what the regulations mandate.
And at these frequencies, you'd basically have to climb the tower and hug the antenna to exceed the occupational exposure limits. It's a non-issue for wireless towers. Broadcast FM & TV, and high-power radar/microwave are another story.
J
Jan Panteltje
Guest
On a sunny day (Sun, 9 Jun 2019 11:44:18 +0100) it happened Piglet
<erichpwagner@hotmail.com> wrote in <qdinu0$137$1@dont-email.me>:
Interesting,
so better stay away from those dishes!
<erichpwagner@hotmail.com> wrote in <qdinu0$137$1@dont-email.me>:
On 09/06/2019 11:26, Jan Panteltje wrote:
On a sunny day (Sun, 9 Jun 2019 10:33:42 +0100) it happened Piglet
erichpwagner@hotmail.com> wrote in <qdijpl$cgl$1@dont-email.me>:
On 09/06/2019 08:15, Jan Panteltje wrote:
That does not bother me, but anything near 2.4 GHz you better watch out for.
Why are you worried by 2.4GHz?
piglet
It is close to the same frequency that heats stuff in your microwave.
It is more the power that causes the heating than hitting the "right
frequency". Industrial microwave ovens use other frequencies too. I'd be
just as worried being near 800W at L or C band.
https://en.wikipedia.org/wiki/Electromagnetic_absorption_by_water#/media/File
Interesting,
so better stay away from those dishes!
P
Piglet
Guest
On 09/06/2019 12:24, mpm wrote:
Does that mean avoid vertical polarized VHF when standing and horizontal
polarized VHF when lying down ?
piglet
Does that mean avoid vertical polarized VHF when standing and horizontal
polarized VHF when lying down ?
piglet
Guest
Jan Panteltje <pNaOnStPeAlMtje@yahoo.com> wrote in
news:qdimtv$rqc$1@dont-email.me:
But nowhere near the power level or proximity.
news:qdimtv$rqc$1@dont-email.me:
But nowhere near the power level or proximity.
Guest
On Sun, 9 Jun 2019 04:15:05 -0700 (PDT), mpm <mpmillard@aol.com>
wrote:
Apparently that US figures refers to some general public IEEE
radiation limits of 27,5 V/m or 2 W/m˛ for 6 min average exposure at
10-400 MHz. At lower and higher frequencies, the limits are higher.
It is interesting to note that while Russian standards allow similar
power densities for 6 minutes, the limit for 8 hour occupational
exposure is only 0.25 W/m˛
I saw an interview with a former antenna installer who was climbing
the tower containing a high power UHF TV antenna. The transmitter was
supposed to be off during the installation, but it was on. The
installer was able to climb down but was unable to continue his job as
a tower installer.
wrote:
Apparently that US figures refers to some general public IEEE
radiation limits of 27,5 V/m or 2 W/m˛ for 6 min average exposure at
10-400 MHz. At lower and higher frequencies, the limits are higher.
It is interesting to note that while Russian standards allow similar
power densities for 6 minutes, the limit for 8 hour occupational
exposure is only 0.25 W/m˛
I saw an interview with a former antenna installer who was climbing
the tower containing a high power UHF TV antenna. The transmitter was
supposed to be off during the installation, but it was on. The
installer was able to climb down but was unable to continue his job as
a tower installer.
Guest
On Sun, 9 Jun 2019 04:24:05 -0700 (PDT), mpm <mpmillard@aol.com>
wrote:
Yes, the human length or limb length are at 1/4, 1/2 or 1/1 wavelength
resonance and this is the reason why the IEEE standard specifies 27.5
V/m for 10 to 400 MHz. The IEEE standard is also used by a multitude
of national standards.
wrote:
Yes, the human length or limb length are at 1/4, 1/2 or 1/1 wavelength
resonance and this is the reason why the IEEE standard specifies 27.5
V/m for 10 to 400 MHz. The IEEE standard is also used by a multitude
of national standards.
A
amdx
Guest
On 6/8/2019 9:35 PM, Jeff Liebermann wrote:
compounded $538,316. 30 years $1,475,529. That's not accounting for
taxes or any inflation increase or loss of value because of inflation.
Mikek
I like investing the $9600 a year, Stock Market say 9% over 20 years
compounded $538,316. 30 years $1,475,529. That's not accounting for
taxes or any inflation increase or loss of value because of inflation.
Mikek
J
Jeff Liebermann
Guest
On 8 Jun 2019 10:55:09 -0700, Winfield Hill <winfieldhill@yahoo.com>
wrote:
Nope. What you want is an RF absorber, not a reflector. Tin foil and
aluminum are reflectors and simply reflect the signal in another
direction. While that would be effective if the entire house were
shielded on all sides, it doesn't do much good if RF leaks into the
house through an opening, such as a door or window, and then bounces
around. At microwave frequencies, such the new 5G 24 to 40GHz
frequencies, RF can wiggle through small (half wave) cracks in the
metal wall. Incidentally, AT&T is testing at 38GHz. At best,
reflective shielding only extends the path loss by the distance of
each reflection. At worst, if one lives in a circular house,
reflections concentrate the RF.
What he really needs is an RF absorber as used in an anechoic RF test
chamber:
<https://www.google.com/search?q=RF+anechoic+chamber&tbm=isch>
The pyramid shaped structures are made from carbon impregnated foam.
The pyramid shape avoids any resonances and allows the foam to absorb
a wide range of frequencies.
<https://www.theemcshop.com/561-foam-rf-absorber-anechoic-chamber>
As an added bonus, if there's any nearby street noise, the foam cones
really quiet down the house. Most anechoic RF test chambers use both
metal reflective shielding and absorbers as well as metal finger stock
around all the doors to totally seal the chamber. If the home owner
has lots of money, such overkill might be appropriate.
Incidentally, the predicted useful range of mm wave 5G is rather
short. See table at:
<https://en.wikipedia.org/wiki/5G#FR2_Network_coverage>
Drivel:
If the owner really wants to reduce RF exposure inside his house, he
should ask AT&T to build a macrocell monster tower that straddles his
house. Directly under the antenna has the lowest RF exposure.
Typical RF exposure report required for building a cell site.
<http://www.learnbydestroying.com/jeffl/coverage/VZW-water-plant/205061-%20RF%20EME%20Compliance%20Report-2.4.13.pdf>
Associated lease agreement (for $1,752/mo plus 4% annual increases).
<http://www.learnbydestroying.com/jeffl/coverage/VZW-water-plant/Lease-Agreement.pdf>
Proposed site plan:
<http://www.learnbydestroying.com/jeffl/coverage/VZW-water-plant/VZW.Brookdale.Drawings.pdf>
"FIELD INTENSITY and POWER DENSITY"
<http://www.learnbydestroying.com/jeffl/coverage/VZW-water-plant/Field%20Intensity%20and%20Power%20Density.pdf>
--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
wrote:
Nope. What you want is an RF absorber, not a reflector. Tin foil and
aluminum are reflectors and simply reflect the signal in another
direction. While that would be effective if the entire house were
shielded on all sides, it doesn't do much good if RF leaks into the
house through an opening, such as a door or window, and then bounces
around. At microwave frequencies, such the new 5G 24 to 40GHz
frequencies, RF can wiggle through small (half wave) cracks in the
metal wall. Incidentally, AT&T is testing at 38GHz. At best,
reflective shielding only extends the path loss by the distance of
each reflection. At worst, if one lives in a circular house,
reflections concentrate the RF.
What he really needs is an RF absorber as used in an anechoic RF test
chamber:
<https://www.google.com/search?q=RF+anechoic+chamber&tbm=isch>
The pyramid shaped structures are made from carbon impregnated foam.
The pyramid shape avoids any resonances and allows the foam to absorb
a wide range of frequencies.
<https://www.theemcshop.com/561-foam-rf-absorber-anechoic-chamber>
As an added bonus, if there's any nearby street noise, the foam cones
really quiet down the house. Most anechoic RF test chambers use both
metal reflective shielding and absorbers as well as metal finger stock
around all the doors to totally seal the chamber. If the home owner
has lots of money, such overkill might be appropriate.
Incidentally, the predicted useful range of mm wave 5G is rather
short. See table at:
<https://en.wikipedia.org/wiki/5G#FR2_Network_coverage>
Drivel:
If the owner really wants to reduce RF exposure inside his house, he
should ask AT&T to build a macrocell monster tower that straddles his
house. Directly under the antenna has the lowest RF exposure.
Typical RF exposure report required for building a cell site.
<http://www.learnbydestroying.com/jeffl/coverage/VZW-water-plant/205061-%20RF%20EME%20Compliance%20Report-2.4.13.pdf>
Associated lease agreement (for $1,752/mo plus 4% annual increases).
<http://www.learnbydestroying.com/jeffl/coverage/VZW-water-plant/Lease-Agreement.pdf>
Proposed site plan:
<http://www.learnbydestroying.com/jeffl/coverage/VZW-water-plant/VZW.Brookdale.Drawings.pdf>
"FIELD INTENSITY and POWER DENSITY"
<http://www.learnbydestroying.com/jeffl/coverage/VZW-water-plant/Field%20Intensity%20and%20Power%20Density.pdf>
--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
J
Jeff Liebermann
Guest
On Sun, 09 Jun 2019 11:03:09 GMT, Jan Panteltje
<pNaOnStPeAlMtje@yahoo.com> wrote:
Perhaps purchasing a "personal RF safety monitor"
<https://en.wikipedia.org/wiki/Personal_RF_safety_monitor>
such as:
<https://www.fieldsense.com>
Version 2 is only $600. Carry one of these and you don't need to
guess if that nearby antenna will turn your brain to mush. I don't
climb towers any more, but if I did today, I would probably purchase
or build something similar.
You can probably use a much cheaper 3 axis RF field strength meter:
<https://www.google.com/search?q=3+axis+rf+field+strength+meter&tbm=isch>
However, you might need to do some calculations and graph reading to
determine if you're safe. You will also need to know the frequencies
involved in order to make the determination.
--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
<pNaOnStPeAlMtje@yahoo.com> wrote:
Perhaps purchasing a "personal RF safety monitor"
<https://en.wikipedia.org/wiki/Personal_RF_safety_monitor>
such as:
<https://www.fieldsense.com>
Version 2 is only $600. Carry one of these and you don't need to
guess if that nearby antenna will turn your brain to mush. I don't
climb towers any more, but if I did today, I would probably purchase
or build something similar.
You can probably use a much cheaper 3 axis RF field strength meter:
<https://www.google.com/search?q=3+axis+rf+field+strength+meter&tbm=isch>
However, you might need to do some calculations and graph reading to
determine if you're safe. You will also need to know the frequencies
involved in order to make the determination.
--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
A
amdx
Guest
On 6/9/2019 10:37 AM, Jeff Liebermann wrote:
Hey Jeff, how would I find out where my local 5G tower fits in the chart
you posted here,> https://en.wikipedia.org/wiki/5G#FR2_Network_coverage
the pole,
The Building permit,
> https://www.dropbox.com/s/g5sq29hlzlcrq2l/5G%20Permit.jpg?dl=0
Not worried about RF, just want to know if it will be of use to me.
I suspect it will be, I'm 1450ft away.
Mikek
PS, the next closest 5G tower I'm aware of, is 1.9 miles away.
Hey Jeff, how would I find out where my local 5G tower fits in the chart
you posted here,> https://en.wikipedia.org/wiki/5G#FR2_Network_coverage
the pole,
The Building permit,
> https://www.dropbox.com/s/g5sq29hlzlcrq2l/5G%20Permit.jpg?dl=0
Not worried about RF, just want to know if it will be of use to me.
I suspect it will be, I'm 1450ft away.
Mikek
PS, the next closest 5G tower I'm aware of, is 1.9 miles away.
J
Jeff Liebermann
Guest
On Sun, 09 Jun 2019 07:15:15 GMT, Jan Panteltje
<pNaOnStPeAlMtje@yahoo.com> wrote:
I don't see a problem:
<http://www.learnbydestroying.com/jeffl/crud/Dish-overload.jpg>
Due to the need for more bandwidth than a point to point microwave
link can provide, and to avoid difficulties with frequency
coordination and FCC licensing, most backhauls are moving to fiber
optic. At this time, my guess(tm) is about 40% use microwave, 40% use
some form of fiber, and the remaining 20% use copper (usually supplied
by the local telco). As additional bandwidth is needed at the larger
sites, the limited throughput microwave radios are being replaced by
fiber. Microwave will still be used where the terrain or lack of
infrastructure makes fiber impractical.
--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
<pNaOnStPeAlMtje@yahoo.com> wrote:
I don't see a problem:
<http://www.learnbydestroying.com/jeffl/crud/Dish-overload.jpg>
Due to the need for more bandwidth than a point to point microwave
link can provide, and to avoid difficulties with frequency
coordination and FCC licensing, most backhauls are moving to fiber
optic. At this time, my guess(tm) is about 40% use microwave, 40% use
some form of fiber, and the remaining 20% use copper (usually supplied
by the local telco). As additional bandwidth is needed at the larger
sites, the limited throughput microwave radios are being replaced by
fiber. Microwave will still be used where the terrain or lack of
infrastructure makes fiber impractical.
--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
J
Jan Panteltje
Guest
On a sunny day (Sun, 09 Jun 2019 09:03:42 -0700) it happened Jeff Liebermann
<jeffl@cruzio.com> wrote in <10aqfe9295ulptso7ahp43o3l56nka09lc@4ax.com>:
Yes, indeed there is a tendency towards fiber,
and the future 5G also needs that
but over here in the country that part of the infrastructure is not there yet.
I do have 3 cellphone towers to chose from at home...
Would not you be just as worried if a 24 GHz antenna was on a street light
next to your bedroom window?
I have a street light on a high pole in front of the house...
Personally I think 5G is largely a hype.
I use internet extensively, and do not feel the need for higher speed really.
OTOH some people think it is cool to put HD movies on youtube with no
other content than them babbling along.
That would be better in a postage stamp size low resolution window...
It is the same with ultra HD TV,
it is the content that counts, not the resolution!
But then a new standard every few year sells new stuff.
<end rant (for now)>
<jeffl@cruzio.com> wrote in <10aqfe9295ulptso7ahp43o3l56nka09lc@4ax.com>:
Yes, indeed there is a tendency towards fiber,
and the future 5G also needs that
but over here in the country that part of the infrastructure is not there yet.
I do have 3 cellphone towers to chose from at home...
Would not you be just as worried if a 24 GHz antenna was on a street light
next to your bedroom window?
I have a street light on a high pole in front of the house...
Personally I think 5G is largely a hype.
I use internet extensively, and do not feel the need for higher speed really.
OTOH some people think it is cool to put HD movies on youtube with no
other content than them babbling along.
That would be better in a postage stamp size low resolution window...
It is the same with ultra HD TV,
it is the content that counts, not the resolution!
But then a new standard every few year sells new stuff.
<end rant (for now)>