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Behind the times...
Perhaps someone can answer a question or two about synthetic aperture radar
systems. I'm interested in whether or not the flat plate we see as the receiver antenna actually radiates power, or is a separate transmitter antenna used? TIA Ed, NM2K |
#2
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Behind the times...
"Ed" == Ed Cregger writes:
Ed Perhaps someone can answer a question or two about synthetic Ed aperture radar systems. I'm interested in whether or not the Ed flat plate we see as the receiver antenna actually radiates yes it does. Some old design had slotted waveguides and a common transmitter, more modern units have separate transmitters for each dipole, or for a row of dipoles. Ed power, or is a separate transmitter antenna used? TIA no, a separate antenna is not necessary, not at least for "normal" air traffic control/air surveillance radars. Those huge OTH monsters are a different beast of course... The separate thing you see on most radars is the IFF antenna, recognizable because it is turned a few degrees ahead of the main beam. Pf, ik5pvx -- Pierfrancesco Caci |
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Behind the times...
Ed Cregger wrote:
Perhaps someone can answer a question or two about synthetic aperture radar systems. I'm interested in whether or not the flat plate we see as the receiver antenna actually radiates power, or is a separate transmitter antenna used? TIA Ed, NM2K You mean on something like this? http://www.raytheon.com/capabilities..._tpq37_pdf.pdf It would depend on the design, but in general, yes, the flat plate does both. -- Jim Pennino Remove .spam.sux to reply. |
#4
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Behind the times...
On Oct 31, 1:27 pm, "Ed Cregger" wrote:
Perhaps someone can answer a question or two about synthetic aperture radar systems. I'm interested in whether or not the flat plate we see as the receiver antenna actually radiates power, or is a separate transmitter antenna used? TIA Ed, NM2K Synthetic Aperture Radar (SAR) isn't usually the rotating antenna thing. SAR would be on some sort of moving platform (a plane or satellite, for instance, although SARs have been done on cars and boats and balloons) Perhaps what you're thinking about is a phased array antenna? The flat plate thing is the antenna, and might be either totally passive (and can work for both transmit and receive) or active, with lots of T/R modules. |
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Behind the times...
On Fri, 31 Oct 2008 16:27:47 -0400, "Ed Cregger"
wrote: Perhaps someone can answer a question or two about synthetic aperture radar systems. I'm interested in whether or not the flat plate we see as the receiver antenna actually radiates power, or is a separate transmitter antenna used? TIA Ed, NM2K As others have mentioned, that's not synthetic aperture radar. See the article at: http://en.wikipedia.org/wiki/Synthetic_aperture_radar for explanations and references. Note that either the target or the radar has to be moving for SAR to work. A mess of small transmitters, scattered over a wide area, will also work. A rotating radar antenna (phased array, bedspring, or dish) will not work. One example is the SRTM (Shuttle Radar Topography Mission), which used interferometry and a synthetic aperture radar to map the planet. In this case, the shuttle was moving and the ground was relatively motionless. http://fas.org/irp/program/collect/ifsar.htm http://www2.jpl.nasa.gov/srtm/ Since there was only one space shuttle in orbit, the antenna must both xmit and receive. -- # Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060 # 831-336-2558 # http://802.11junk.com # http://www.LearnByDestroying.com AE6KS |
#6
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Behind the times...
wrote in message ... On Oct 31, 1:27 pm, "Ed Cregger" wrote: Perhaps someone can answer a question or two about synthetic aperture radar systems. I'm interested in whether or not the flat plate we see as the receiver antenna actually radiates power, or is a separate transmitter antenna used? TIA Ed, NM2K Synthetic Aperture Radar (SAR) isn't usually the rotating antenna thing. SAR would be on some sort of moving platform (a plane or satellite, for instance, although SARs have been done on cars and boats and balloons) Perhaps what you're thinking about is a phased array antenna? The flat plate thing is the antenna, and might be either totally passive (and can work for both transmit and receive) or active, with lots of T/R modules. ------------ I was thinking of the Aegis class warships. Ed Cregger |
#7
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Behind the times...
"Jeff Liebermann" wrote in message ... On Fri, 31 Oct 2008 16:27:47 -0400, "Ed Cregger" wrote: Perhaps someone can answer a question or two about synthetic aperture radar systems. I'm interested in whether or not the flat plate we see as the receiver antenna actually radiates power, or is a separate transmitter antenna used? TIA Ed, NM2K As others have mentioned, that's not synthetic aperture radar. See the article at: http://en.wikipedia.org/wiki/Synthetic_aperture_radar for explanations and references. Note that either the target or the radar has to be moving for SAR to work. A mess of small transmitters, scattered over a wide area, will also work. A rotating radar antenna (phased array, bedspring, or dish) will not work. One example is the SRTM (Shuttle Radar Topography Mission), which used interferometry and a synthetic aperture radar to map the planet. In this case, the shuttle was moving and the ground was relatively motionless. http://fas.org/irp/program/collect/ifsar.htm http://www2.jpl.nasa.gov/srtm/ Since there was only one space shuttle in orbit, the antenna must both xmit and receive. ----------- Thanks for the explanations, all. Much appreciated. Ed, NM2K |
#8
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Behind the times...
In article ,
Ed Cregger wrote: I was thinking of the Aegis class warships. I believe that the Aegis warship radar is a phased-array system, akin to the PAVE PAWS radars that have been in the ham press lately due to QRM issues on both the east and west coasts of the US (some ham 440 repeater systems have been required to mitigate interference to PAVE PAWS and some have gone off the air as a result). -- Dave Platt AE6EO Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior I do _not_ wish to receive unsolicited commercial email, and I will boycott any company which has the gall to send me such ads! |
#9
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Behind the times...
On Sat, 1 Nov 2008 11:11:32 -0400, "Ed Cregger"
wrote: systems. I'm interested in whether or not the flat plate we see as the receiver antenna actually radiates power, or is a separate transmitter antenna used? TIA I was thinking of the Aegis class warships. Hi Ed, The "flat plate" is acually a mosaic of 4100 phased elements driven by a single RF source. 73's Richard Clark, KB7QHC |
#10
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Behind the times...
On Sat, 1 Nov 2008 11:11:32 -0400, "Ed Cregger"
wrote: I was thinking of the Aegis class warships. See: AN/SPY-1. 4 panels with 4 megawatts in S-band. http://en.wikipedia.org/wiki/AN/SPY-1 http://www.globalsecurity.org/military/systems/ship/systems/an-spy-1.htm https://wrc.navair-rdte.navy.mil/warfighter_enc/weapons/SensElec/RADAR/anspy1.htm Lots of fun when the beam hits an adjacent vessels antenna farm and toasts everything connected to it. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
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