SAR Satellites

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SAR Satellites

sailplane
This post was updated on .
https://en.wikipedia.org/wiki/Synthetic-aperture_radar
"To create a SAR image, successive pulses of radio waves are transmitted to "illuminate" a target scene, and the echo of each pulse is received and recorded. The pulses are transmitted and the echoes received using a single beam-forming antenna, with wavelengths of a meter down to several millimeters. "

https://spacenews.com/capella-space-raises-19-million-for-radar-constellation/
36 satellites, to "photograph" every space on earth, every hour... First one launching Nov 19.

There are already quite a bunch of SAR Satellites, but likely pointed at areas of interest.. These ones will point to all areas eventually..

Some numbers and frequencies are given here:
https://upcommons.upc.edu/bitstream/handle/2099.1/6631/Final.pdf

360Watts, from 500km away.. sounds like it's not really strong at all.. but it will be interesting, as the most remote areas on earth will slowly get more and more satellite transmissions and there will not be any place left that is 'quiet'..
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Re: SAR Satellites

casper
This post was updated on .
sailplane wrote
360Watts, from 500km away.. sounds like it's not really strong at all.. but it will be interesting, as the most remote areas on earth will slowly get more and more satellite transmissions and there will not be any place left that is 'quiet'..
Don't be fooled by this. You have to understand that there is something called "antenna gain". It basically describes how directional an antenna is. So in theory you could have all this 360 watts directed onto a small 1x1m square at the surface of the earth. Then you'd have theoretical power density of 360W/m2 at the surface. This fill fry everything.

One of the satellites in the PDF had an antenna gain of 42 dB.

If you then go to this page:
http://sss-mag.com/calcdb.html

And you input 360W and 42 dB, you will get an EIRP (effective power of an equivalent point source) of 5705622 watts. That's not peanuts any more. This is a very directional antenna.

To calculate the power density at the earth's surface though is above my skills, but this should give some idea about how antennas interact with transmitter power. It's all about directionality, and that means in addition to power, the antenna gain is important to know too.
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Re: SAR Satellites

sailplane
casper wrote
sailplane wrote
360Watts, from 500km away.. sounds like it's not really strong at all.. but it will be interesting, as the most remote areas on earth will slowly get more and more satellite transmissions and there will not be any place left that is 'quiet'..
Don't be fooled by this. You have to understand that there is something called "antenna gain". It basically describes how directional an antenna is. So in theory you could have all this 360 watts directed onto a small 1x1m square at the surface of the earth. Then you'd have theoretical power density of 360W/m2 at the surface. This fill fry everything.

One of the satellites in the PDF had an antenna gain of 42 dB.

If you then go to this page:
http://sss-mag.com/calcdb.html

And you input 360W and 42 dB, you will get an EIRP (effective power of an equivalent point source) of 5705622 watts. That's not peanuts any more. This is a very directional antenna.

To calculate the power density at the earth's surface though is above my skills, but this should give some idea about how antennas interact with transmitter power. It's all about directionality, and that means in addition to power, the antenna gain is important to know too.
Thanks for the info.. Yes I saw 42dB, but I didn't know how to calculate it in. 42db is huge. Looks like these antennas are similar to airport radar, they are very directional but fly past at a very high speed, so the burst would only last maybe 100th of a second.  But once they fully implement this system it will do that 24 times a day.  I would think the  power should be quite strong if it has the ability to bounce off the ground and back up so many kilometers.  It's not merely two antennas talking to each other, it's relying on reflectivity.. Cars would be good reflectors..

It's interesting, they can probably see people inside their homes with this.. roofs are made of wood and shingles here, not very good at blocking much RF. The human body would probably reflect more than the wood..

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Re: SAR Satellites

casper
sailplane wrote
Looks like these antennas are similar to airport radar, they are very directional but fly past at a very high speed, so the burst would only last maybe 100th of a second.  But once they fully implement this system it will do that 24 times a day.
Yes, I think it's quite scary how they are continuously adding more RF pollution. Even if it's 100th of a second, it's probably still not a good idea. And now we have the SpaceX project coming up also.

Time to start building houses with RF blocking roofs.
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Re: SAR Satellites

sailplane
Metal roof, it's more expensive but it lasts forever.. some people have it.
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Re: SAR Satellites

Canaree2018
You don't want a metal roof ,trust me. I had to leave my nice home near the water because I have a metal roof and a nearby weather/ cell pj
hone  antenna was literally attaching to it and the home became unlivable.
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Re: SAR Satellites

casper
Canaree2018 wrote
You don't want a metal roof ,trust me.
I had to leave my nice home near the water because I have a metal roof and a nearby weather/ cell pj
hone antenna was literally attaching to it and the home became unlivable.
Did you ever try to ground the roof? I wonder if that would have helped...
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Re: SAR Satellites

BeyondThreshold
In reply to this post by casper
casper wrote
sailplane wrote
Looks like these antennas are similar to airport radar, they are very directional but fly past at a very high speed, so the burst would only last maybe 100th of a second.  But once they fully implement this system it will do that 24 times a day.
Yes, I think it's quite scary how they are continuously adding more RF pollution. Even if it's 100th of a second, it's probably still not a good idea. And now we have the SpaceX project coming up also.

Time to start building houses with RF blocking roofs.
Building houses wish a RF faraday cage might be a better option?  By the way, more RF pollution is not are only problem.  "Currently, there are about 1,500 satellites orbiting Earth and that will change to 15,000 within massive risks of using mercury as the propellant in thousands of communication satellites slated for launch in the next few years".  https://www.peer.org/news/press-releases/mercury-may-reach-orbit-through-regulatory-blindspot.html
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Re: SAR Satellites

Marc Martin
Administrator
> "Currently, there are about
> 1,500 satellites orbiting Earth and that will change to 15,000 within
> massive risks of using mercury as the propellant in thousands of
> communication satellites slated for launch in the next few years".

So in the past 60 years, all of mankind has managed to get 1,500 satellites up.  
And someone thinks they they alone can launch 10 times that many satellites
in only a few years?  

Having once worked in the satellite launch industry, that sounds completely
absurd.  Most likely they will go out of business.

Marc
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Re: SAR Satellites

BeyondThreshold
Marc Martin wrote
> "Currently, there are about
> 1,500 satellites orbiting Earth and that will change to 15,000 within
> massive risks of using mercury as the propellant in thousands of
> communication satellites slated for launch in the next few years".

So in the past 60 years, all of mankind has managed to get 1,500 satellites up.  
And someone thinks they they alone can launch 10 times that many satellites
in only a few years?  

Having once worked in the satellite launch industry, that sounds completely
absurd.  Most likely they will go out of business.

Marc
Don't underestimate the wireless industries pockets.  The telecommunications & tech industry has the highest number of lobbyist in Washington D.C..  The use of Mercury as a propulsion is a cheaper route than the conventional rockets and currently there is a robust market for wireless everything (which seems to be a low risk investment?).  Apollo Fusion is the company launching these rockets and I believe it's SpaceX, OneWeb, and other major communication companies are flipping the bill?  According to the PEER complaint to the FCC, Apollo Fusion (a Silicon Valley company) will be launching as mush as 198 tonnes of Mercury into orbit with 20 tonnes of Mercury falling into the atmosphere/year, w/ the majority emitted for the initial orbital.  A 2018 study shows that U.S. & Canada combined emitted only 40 tonnes of Mercury into the air in 2015 alone.

As for radiation emissions, we have seen nothing yet, with the coming of 5G, these newer Satellites emitting RF down on us, newer cars with visual scanning cameras, laser sensors, and lots of microwave radar systems, etc!
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Re: SAR Satellites

BeyondThreshold
And of course, the tech and wireless industry also has captured the FCC, Congress, President, Supreme Court, and other U.S. Agencies.