Is it normal to lose 15 dB @ 2.4Ghz through double-pane windowglass?
Is it normal to lose 15 dB @ 2.4Ghz through double-pane windowglass?. Discuss Is it normal to lose 15 dB @ 2.4Ghz through double-pane windowglass?, on Wireless Forums.
Re: Is it normal to lose 15 dB @ 2.4Ghz through double-pane window glass?
On Sat, 24 Mar 2012 05:28:39 +0000 (UTC), "Martin C."
<martincella3ca@nospam-gmail.com> wrote:
>Oooops. I hit the send keystroke before I was finished.
>
>Here is the picture of my temporary 2.4Ghz setup:
> http://picturepush.com/public/7867744
>
>OUTSIDE: I get -77 dB received signal on AirOS.
>INSIDE: I get -92 dB received signal on AirOS.
>
>The difference is that it won't work inside; but it works fine outside
>(just a foot or two away) on the deck outside the window.
>
>It's not the screen (as it's cloth and we tested that).
>It's the window (which we tested by opening it up).
>
>Since it's cold and windy on the deck, we would like to use the antenna
>inside. First we have to figure out WHY we lose 15 dB through a simple
>window!
>
>Can someone tell me why?
People more knowledgeable than me will be along shortly, I presume,
but my guess is that the window glass has an energy efficient coating
that blocks much of the signal.
It wouldn't surprise me if you did a lot better by moving the antenna
to either side of the window. That may give you significantly more
signal to work with.
Re: Is it normal to lose 15 dB @ 2.4Ghz through double-pane window glass?
On Sat, 24 Mar 2012 05:28:39 +0000 (UTC), "Martin C."
<martincella3ca@nospam-gmail.com> wrote:
>It's the window (which we tested by opening it up).
Is the glass coated with a titanium nitride or titanium dioxide, Low-E
IR reflective coating? It's blocks RF quite nicely at about 45 ohms
per square resistivity.
Not a great data sheet on the topic, but it does offer some clues:
<http://802.11junk.com/jeffl/crud/Low-E-titanium-nitide-glass.pdf>
Re: Is it normal to lose 15 dB @ 2.4Ghz through double-pane windowglass?
On Sat, 24 Mar 2012 00:36:50 -0700, Jeff Liebermann wrote:
> Is the glass coated with a titanium nitride or titanium dioxide, Low-E
> IR reflective coating?
Hi Jeff,
I have no idea what the window is made of, but you gave me a hint so I
did find this document which says a typical coated (doesn't say which
coating) double-pane window will attenuate by 13 decibels whereas a
'normal' exterior window will only attenuate 7 Db.
Re: Is it normal to lose 15 dB @ 2.4Ghz through double-pane windowglass?
On Sat, 24 Mar 2012 00:36:50 -0700, Jeff Liebermann wrote:
> titanium nitride or titanium dioxide, Low-E
> IR reflective coating?
> It's blocks RF quite nicely at about 45 ohms per square resistivity.
Hi Jeff,
I'm in the Santa Cruz mountains, with more sun than I know what to do
with, so it would make sense the previous owner used a special coated
glass.
Re: Is it normal to lose 15 dB @ 2.4Ghz through double-pane window glass?
On Sat, 24 Mar 2012 15:09:46 +0000 (UTC), "Martin C."
<martincella3ca@nospam-gmail.com> wrote:
>On Sat, 24 Mar 2012 00:36:50 -0700, Jeff Liebermann wrote:
>> Is the glass coated with a titanium nitride or titanium dioxide, Low-E
>> IR reflective coating?
>I have no idea what the window is made of, but you gave me a hint so I
>did find this document which says a typical coated (doesn't say which
>coating) double-pane window will attenuate by 13 decibels whereas a
>'normal' exterior window will only attenuate 7 Db.
>http://www.ci.cumberland.md.us/new_s...tents/view/635
Site seems to be down at this time. Low-E has been required for new
construction in California since about 2002. From your photo, the
window construction looks very recent and will likely use Low-E glass.
The numbers for attenuation through various materials vary wildly
depending on testing methodology. For example, if your test radio is
fairly close to the window, you will get some value. However, if the
window is not much larger than the antenna, and you back off some
distance from the window, it starts to look like an aperature,
complete with edge diffraction and Fresnel zone effects. Size matters
as does angle of incidence. In your photo at:
<http://picturepush.com/public/7867744>
The dish is much too close to the window frame at the top.
Table of attenuations (unfortunately missing Low-E glass.
<http://wireless.navas.us/index.php?title=Wi-Fi#Attenuation>
In the not so distant past, I installed a wireless access point at a
car wash. The router and antenna were inside, while the customers
were mostly outside. In between was a rather large plate glass
picture window. To 2.4/5.7GHz, it was almost like a shielded wall. I
never bothered to measure the loss, but it was sufficiently high to
require installing a 2nd outside wireless access point to give the
customers some coverage.
Meanwhile, the local university installed Low-E glass in several new
buildings, only to find that its micro-cellular rooftop system didn't
work inside the buildings. Indoor radios had to be added in some
buildings.
There are various creative ways to identify Low-E glass:
<http://ths.gardenweb.com/forums/load/remodel/msg101424515094.html>
I use an IR thermometer and anything hot, such as a cigarette igniter.
If the heat from the lighter goes through the glass, it's not Low-E.
If it blocks IR, it's Low-E. If you can't get to both sides of the
glass, check if it reflects IR.
Re: Is it normal to lose 15 dB @ 2.4Ghz through double-pane window glass?
On Sat, 24 Mar 2012 15:25:02 +0000 (UTC), "Martin C."
<martincella3ca@nospam-gmail.com> wrote:
>On Sat, 24 Mar 2012 00:36:50 -0700, Jeff Liebermann wrote:
>> titanium nitride or titanium dioxide, Low-E
>> IR reflective coating?
>> It's blocks RF quite nicely at about 45 ohms per square resistivity.
>I'm in the Santa Cruz mountains, with more sun than I know what to do
>with, so it would make sense the previous owner used a special coated
>glass.
I'm in the trees in Ben Lomond. Send me some of that sun as the deep
dark forest gets to me every winter.
It's not so special. Low-E is has been required for new construction
and permitted remodels for at least 10 years in SCZ county.
>Looking up more details, I found this "Residential Glass Technical Guide":
><http://www.cardinalcorp.com/wp-content/uploads/pdf/residential-brochure.pdf>
>But I can't tell what coating they used.
Most Low-E materials will block RF. The only one that is specifically
designed to NOT block RF are the nano-ceramic coated variety. Those
are rare, expensive, and optically inferior to the more common
sputtered aluminum or sliver, tin dioxide, titanium nitride, and
titanium dioxide flavors.
Are you using Hilltop Internet or SurfnetC? In both cases, methinks
you should install the dish on the roof, mount the radio behind the
dish to reduce coax cable RF losses, use PoE to run the radio, and do
plenty of waterproofing. There was a long thread in this newsgroup on
the subject of getting wireless service in the SCZ mountains from
Hilltop in this newsgroup recently.
Re: Is it normal to lose 15 dB @ 2.4Ghz through double-pane windowglass?
On Sat, 24 Mar 2012 08:54:58 -0700, Jeff Liebermann wrote:
> Are you using Hilltop Internet or SurfnetC?
There are only these WISP providers in the Santa Cruz Mountains that I
know of which serve my area:
HilltopInternet.com
Surfnetc.com
Ridgewireless.com
Ethericnetworks.com
SuperSpeedy.net
For satellite, there are only two:
Viasat Exede
Hughesnet.com
Re: Is it normal to lose 15 dB @ 2.4Ghz through double-pane windowglass?
It is a matter of fulfilling Ca Title 24. If you don't use low-E glass,
you have to make up the loss elsewhere.
It seems to me the RF shielding of low-e glass is a good thing, given
how the government likes to spy on citizens in the post 9/11 world. ;-)
Also, for us city dwellers, we need all the shielding we can get from
nearby wifi.
Off topic, but I'm about to take a hammer to this f-ing Linksys router.
The wifi portion is locking up. I have to reboot the f-er. I suppose it
can live as an expensive switch.
Re: Is it normal to lose 15 dB @ 2.4Ghz through double-pane window glass?
In <jkoi09$1rj$1@speranza.aioe.org> miso <miso@sushi.com> writes:
>It is a matter of fulfilling Ca Title 24. If you don't use low-E glass,
>you have to make up the loss elsewhere.
>It seems to me the RF shielding of low-e glass is a good thing, given
>how the government likes to spy on citizens in the post 9/11 world. ;-)
>Also, for us city dwellers, we need all the shielding we can get from
>nearby wifi.
>Off topic, but I'm about to take a hammer to this f-ing Linksys router.
>The wifi portion is locking up. I have to reboot the f-er. I suppose it
>can live as an expensive switch.
Before you lose all hope, ye who enter there... see if you've
got another wall wart with a similar rating. Often these
lockups are due to power supply issues.
(Far from always, of course, but it's easy enough to check out).
--
__________________________________________________ ___
Knowledge may be power, but communications is the key dannyb@panix.com
[to foil spammers, my address has been double rot-13 encoded]
Re: Is it normal to lose 15 dB @ 2.4Ghz through double-pane windowglass?
On 3/25/2012 7:54 PM, danny burstein wrote:
> In<jkoi09$1rj$1@speranza.aioe.org> miso<miso@sushi.com> writes:
>
>> It is a matter of fulfilling Ca Title 24. If you don't use low-E glass,
>> you have to make up the loss elsewhere.
>
>> It seems to me the RF shielding of low-e glass is a good thing, given
>> how the government likes to spy on citizens in the post 9/11 world. ;-)
>> Also, for us city dwellers, we need all the shielding we can get from
>> nearby wifi.
>
>> Off topic, but I'm about to take a hammer to this f-ing Linksys router.
>> The wifi portion is locking up. I have to reboot the f-er. I suppose it
>> can live as an expensive switch.
>
> Before you lose all hope, ye who enter there... see if you've
> got another wall wart with a similar rating. Often these
> lockups are due to power supply issues.
>
> (Far from always, of course, but it's easy enough to check out).
>
Unfortunately it is a 12V regulated switcher. I will have to either
bench it or buy another wall wart. [Actually soap on a rope.] The
coaxial connector isn't standard. [I've often wondered what is the
reason behind so many different two pin power connectors.]
Note that the wired portion works just fine. I suspect if I open it upm
the wifi is an OEM board. That would explain one function being flaky
while the rest of the box works.
I'll haul the wall wart with me on the next trip to the surplus shop and
see if I can get a match.
Re: Is it normal to lose 15 dB @ 2.4Ghz through double-pane window glass?
On Saturday, March 24, 2012 1:23:16 AM UTC-4, Martin C. wrote:
> Q: Is it normal to lose 15 decibels through a double-pane window?
>
>
> The storm blew down my 2.4Ghz WISP WiFi antenna ...
>
> So a friend stopped by to lend me his Ubiquiti AirGrid M2 Hi-Power (Tx
> 28dBm, Rx -97dBm) radio & 17x24-inch 20dBi antenna combination.
>
>
>
> He's only about a mile away so he opened up his Internet service to me to
> mooch off of until I could get my WISP antenna back in working order.
>
> The problem
After I installed Low E windows in my house I could no longer use my laptop out on the patio. Bummer that was my favorite Sunday morning retreat.
>On Saturday, March 24, 2012 1:23:16 AM UTC-4, Martin C. wrote:
>> Q: Is it normal to lose 15 decibels through a double-pane window?
>>
>>
>> The storm blew down my 2.4Ghz WISP WiFi antenna ...
>>
>> So a friend stopped by to lend me his Ubiquiti AirGrid M2 Hi-Power (Tx
>> 28dBm, Rx -97dBm) radio & 17x24-inch 20dBi antenna combination.
>>
>>
>>
>> He's only about a mile away so he opened up his Internet service to me to
>> mooch off of until I could get my WISP antenna back in working order.
>>
>> The problem
>
>After I installed Low E windows in my house I could no longer use my laptop out on the patio. Bummer that was my favorite Sunday morning retreat.
It should be pretty simple to add an access point to service that
area.
Re: Is it normal to lose 15 dB @ 2.4Ghz through double-pane window glass?
JIMMIE <jimmie68@gmail.com> wrote:
> On Saturday, March 24, 2012 1:23:16 AM UTC-4, Martin C. wrote:
>> Q: Is it normal to lose 15 decibels through a double-pane window?
>>
>>
>> The storm blew down my 2.4Ghz WISP WiFi antenna ...
>>
>> So a friend stopped by to lend me his Ubiquiti AirGrid M2 Hi-Power (Tx
>> 28dBm, Rx -97dBm) radio & 17x24-inch 20dBi antenna combination.
>>
>>
>>
>> He's only about a mile away so he opened up his Internet service to me to
>> mooch off of until I could get my WISP antenna back in working order.
>>
>> The problem
>
> After I installed Low E windows in my house I could no longer use my
> laptop out on the patio. Bummer that was my favorite Sunday morning retreat.
>
> Jimmie
When the weather warms up, open the window, unless yo got aluminum screen.
Re: Is it normal to lose 15 dB @ 2.4Ghz through double-pane window glass?
"Martin C." <martincella3ca@nospam-gmail.com> wrote:
> On Wed, 04 Apr 2012 01:37:59 +0000, gregz wrote:
>
>> When the weather warms up, open the window,
>> unless yo got aluminum screen.
>
> Screen is cloth. The antenna that was damaged in the storm is fixed.
> I learned a lot.
> Coated glass can block RF dead!
>
> It's all good now!
>
> Thanks to everyone!
Re: Is it normal to lose 15 dB @ 2.4Ghz through double-pane window glass?
On Thu, 05 Apr 2012 21:08:09 -0700, miso <miso@sushi.com> wrote:
>> A black screen cloth could have attenuation.
>>
>> Greg
>
>Do you think they use carbon?
<http://www.hindawi.com/journals/ijfr/2010/836278/>
See section 1.2:
"A similar cage was constructed as a control, with fiberglass
screen, which is not conductive and which does not block RF
signals, instead of aluminum."
Re: Is it normal to lose 15 dB @ 2.4Ghz through double-pane windowglass?
On 4/6/2012 5:59 PM, Jeff Liebermann wrote:
> On Thu, 05 Apr 2012 21:08:09 -0700, miso<miso@sushi.com> wrote:
>
>>> A black screen cloth could have attenuation.
>>>
>>> Greg
>>
>> Do you think they use carbon?
>
> <http://www.hindawi.com/journals/ijfr/2010/836278/>
> See section 1.2:
> "A similar cage was constructed as a control, with fiberglass
> screen, which is not conductive and which does not block RF
> signals, instead of aluminum."
>
Wow, that is tin foil hat territory. [Yes, I know the foil isn't tin
anymore.] However, the Faraday cage test is probaly OK.
I have some near IR CCDs (response to 1um) and R72 filters. Looking at
black stuff, you find black often isn't black under IR. Some black is
completely transparent to IR, so I have to presume there are different
ways to produce black items. Maybe the black that isn't transparent to
IR has carbon in it.
Is it normal to lose 15 dB @ 2.4Ghz through double-pane windowglass? 
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