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Uses for a TVRO dish antenna?
Anyone have any ideas about what one might do with a television
receive-only (TVRO) antenna? The thing is 10' diameter and it's mine for the price of dismantling it and hauling it out of the present owner's back yard. I'm thinking radio astronomy. Might be nice to make my own radio map of the galaxy. I'm guessing that this would work okay somewhere between 1 and 10 GHz... which means making a feed horn... which is easy enough to do. What else could I do with this antenna? Other than covering it in polyethylene sheet to make a really big bird bath... -- Dave Typinski AJ4CO |
Uses for a TVRO dish antenna?
Dave Typinski wrote:
Anyone have any ideas about what one might do with a television receive-only (TVRO) antenna? The thing is 10' diameter and it's mine for the price of dismantling it and hauling it out of the present owner's back yard. I'm thinking radio astronomy. Might be nice to make my own radio map of the galaxy. I'm guessing that this would work okay somewhere between 1 and 10 GHz... which means making a feed horn... which is easy enough to do. What else could I do with this antenna? Other than covering it in polyethylene sheet to make a really big bird bath... ================================== Possible usage: 1) EME amateur comms 2) WiFi low power experiments (provided there is line of sight freedom) I remember having seen a web site with reports (incl photographs) that some youngsters bridged a 125 km path using off the shelf equipment and dishes having a size like yours. Hopefully you don't have just the dish but also a mounting pedestal and perhaps even a motorised system . Frank GM0CSZ / KN6WH |
Uses for a TVRO dish antenna?
"Dave Typinski" wrote in message
... Anyone have any ideas about what one might do with a television receive-only (TVRO) antenna? The thing is 10' diameter and it's mine for the price of dismantling it and hauling it out of the present owner's back yard. I'm thinking radio astronomy. Might be nice to make my own radio map of the galaxy. I'm guessing that this would work okay somewhere between 1 and 10 GHz... which means making a feed horn... which is easy enough to do. What else could I do with this antenna? Other than covering it in polyethylene sheet to make a really big bird bath... -- Dave Typinski AJ4CO Additional Phase 3 satellites (AMSAT-DL P3E and AMSAT-NA Eagle in the 2009/2010 timeframe) are epected to be lauched in next 24 months -- plenty of leaisurely time to rework and install a BUD for "S' or "C" band -- on a budget. http://www.ultimatecharger.com/dish.html Robert, W0LMD shows you how to build a proper Dish Feed http://www.ultimatecharger.com/Dish_Feed.html |
Uses for a TVRO dish antenna?
"Dave Typinski" wrote in message ... Anyone have any ideas about what one might do with a television receive-only (TVRO) antenna? The thing is 10' diameter and it's mine for the price of dismantling it and hauling it out of the present owner's back yard. I'm thinking radio astronomy. Might be nice to make my own radio map of the galaxy. I'm guessing that this would work okay somewhere between 1 and 10 GHz... which means making a feed horn... which is easy enough to do. What else could I do with this antenna? Other than covering it in polyethylene sheet to make a really big bird bath... -- Dave Typinski AJ4CO Hi Dave NOAAPORT uses a satellite over the Equator, South of Texas to transmit satellite images in near Real Time. You can easily build a station for displaying good images of the Florida as seen from space. Jerry |
Uses for a TVRO dish antenna?
On Sun, 21 Oct 2007 01:01:19 -0400, "Jimmie D"
wrote: "Dave Typinski" wrote in message .. . Anyone have any ideas about what one might do with a television receive-only (TVRO) antenna? The thing is 10' diameter and it's mine for the price of dismantling it and hauling it out of the present owner's back yard. I'm thinking radio astronomy. Might be nice to make my own radio map of the galaxy. I'm guessing that this would work okay somewhere between 1 and 10 GHz... which means making a feed horn... which is easy enough to do. What else could I do with this antenna? Other than covering it in polyethylene sheet to make a really big bird bath... -- Dave Typinski AJ4CO I know of a couple of guys that took two of them, one for rx and one for tx, tx was a microwave oven mgnetron. He and his frined talked to each other via troposcatter. I do know if a maggie operates within a ham band or not but it didnt matter too much for these guys because they didnt have a ticket anyway. Jimmie I thought about magnetrons... but not for communication. My idea is to set it up as a radar station to measure the distance to the Moon. A microwave oven magnetron operates at 2450 MHz, which is right at the upper edge of the 13cm ham band. Unfortunately, magnetrons produce a really dirty, wide output. Worse, being right at the edge of the band, half the RF energy would be out of band. I don't know if one can re-tune a magnetron by the addition of external components; I'd like to get the thing down to 2.42 GHz to put the emission in the center of the 13cm band. There are such things as tunable magnetrons; but, they aren't found in microwave ovens, which means they won't likely be had for free. That said, I'd sure like to look at the output from an oven magnetron with a spectrum analyzer. Maybe the output isn't as dirty and wide as I think it is. -- Dave Typinski AJ4CO |
Uses for a TVRO dish antenna?
On Sun, 21 Oct 2007 11:39:12 +0100, Highland Ham
wrote: Dave Typinski wrote: Anyone have any ideas about what one might do with a television receive-only (TVRO) antenna? The thing is 10' diameter and it's mine for the price of dismantling it and hauling it out of the present owner's back yard. I'm thinking radio astronomy. Might be nice to make my own radio map of the galaxy. I'm guessing that this would work okay somewhere between 1 and 10 GHz... which means making a feed horn... which is easy enough to do. What else could I do with this antenna? Other than covering it in polyethylene sheet to make a really big bird bath... ================================== Possible usage: 1) EME amateur comms 2) WiFi low power experiments (provided there is line of sight freedom) I remember having seen a web site with reports (incl photographs) that some youngsters bridged a 125 km path using off the shelf equipment and dishes having a size like yours. Hopefully you don't have just the dish but also a mounting pedestal and perhaps even a motorised system . Frank GM0CSZ / KN6WH Yep, got the pedestal and the azimuth drive motor. 125 km at 2.4 GHz? How's that work? What were they bouncing the signal off of? That's definitely further than line of sight. -- Dave Typinski AJ4CO |
Uses for a TVRO dish antenna?
On Sun, 21 Oct 2007 06:00:35 -0500, "gb"
wrote: "Dave Typinski" wrote in message .. . Anyone have any ideas about what one might do with a television receive-only (TVRO) antenna? The thing is 10' diameter and it's mine for the price of dismantling it and hauling it out of the present owner's back yard. I'm thinking radio astronomy. Might be nice to make my own radio map of the galaxy. I'm guessing that this would work okay somewhere between 1 and 10 GHz... which means making a feed horn... which is easy enough to do. What else could I do with this antenna? Other than covering it in polyethylene sheet to make a really big bird bath... -- Dave Typinski AJ4CO Additional Phase 3 satellites (AMSAT-DL P3E and AMSAT-NA Eagle in the 2009/2010 timeframe) are epected to be lauched in next 24 months -- plenty of leaisurely time to rework and install a BUD for "S' or "C" band -- on a budget. http://www.ultimatecharger.com/dish.html Robert, W0LMD shows you how to build a proper Dish Feed http://www.ultimatecharger.com/Dish_Feed.html Heh - I had bumped into that web site a coupla months ago, which is what got me thinking about this project. Then I lost the link - so thanks for posting it! -- Dave Typinski AJ4CO |
Uses for a TVRO dish antenna?
On Sun, 21 Oct 2007 16:48:28 GMT, "Jerry Martes"
wrote: "Dave Typinski" wrote in message .. . Anyone have any ideas about what one might do with a television receive-only (TVRO) antenna? The thing is 10' diameter and it's mine for the price of dismantling it and hauling it out of the present owner's back yard. I'm thinking radio astronomy. Might be nice to make my own radio map of the galaxy. I'm guessing that this would work okay somewhere between 1 and 10 GHz... which means making a feed horn... which is easy enough to do. What else could I do with this antenna? Other than covering it in polyethylene sheet to make a really big bird bath... -- Dave Typinski AJ4CO Hi Dave NOAAPORT uses a satellite over the Equator, South of Texas to transmit satellite images in near Real Time. You can easily build a station for displaying good images of the Florida as seen from space. Jerry Now /that/ would be a cool project! Thanks, Jerry. -- Dave Typinski AJ4CO |
Uses for a TVRO dish antenna?
"Dave Typinski" wrote in message ... On Sun, 21 Oct 2007 16:48:28 GMT, "Jerry Martes" wrote: "Dave Typinski" wrote in message . .. Anyone have any ideas about what one might do with a television receive-only (TVRO) antenna? The thing is 10' diameter and it's mine for the price of dismantling it and hauling it out of the present owner's back yard. I'm thinking radio astronomy. Might be nice to make my own radio map of the galaxy. I'm guessing that this would work okay somewhere between 1 and 10 GHz... which means making a feed horn... which is easy enough to do. What else could I do with this antenna? Other than covering it in polyethylene sheet to make a really big bird bath... -- Dave Typinski AJ4CO Hi Dave NOAAPORT uses a satellite over the Equator, South of Texas to transmit satellite images in near Real Time. You can easily build a station for displaying good images of the Florida as seen from space. Jerry Now /that/ would be a cool project! Thanks, Jerry. -- Dave Typinski AJ4CO Hi Dave If you do build a system for receiving the NOAAPORT images, please keep me informed about your progress. I too got my dish free. The PCI card TV receiver was low cost. The rest is computer and software. eBay is a good source of very good antenna parts at low cost. I am presently stuck due to my poor Linux skills, and Linux is used by the guys who write the software (free). Jerry |
Uses for a TVRO dish antenna?
"Dave Typinski" wrote in message ... On Sun, 21 Oct 2007 11:39:12 +0100, Highland Ham wrote: Dave Typinski wrote: Anyone have any ideas about what one might do with a television receive-only (TVRO) antenna? The thing is 10' diameter and it's mine for the price of dismantling it and hauling it out of the present owner's back yard. I'm thinking radio astronomy. Might be nice to make my own radio map of the galaxy. I'm guessing that this would work okay somewhere between 1 and 10 GHz... which means making a feed horn... which is easy enough to do. What else could I do with this antenna? Other than covering it in polyethylene sheet to make a really big bird bath... ================================== Possible usage: 1) EME amateur comms 2) WiFi low power experiments (provided there is line of sight freedom) I remember having seen a web site with reports (incl photographs) that some youngsters bridged a 125 km path using off the shelf equipment and dishes having a size like yours. Hopefully you don't have just the dish but also a mounting pedestal and perhaps even a motorised system . Frank GM0CSZ / KN6WH Yep, got the pedestal and the azimuth drive motor. 125 km at 2.4 GHz? How's that work? What were they bouncing the signal off of? That's definitely further than line of sight. -- Dave Typinski AJ4CO Hi Dave Evidently there are places in or near Venezuela that have line of sight adequate to get WiFi over 380 km. Jerry |
Uses for a TVRO dish antenna?
Anyone have any ideas about what one might do with a television receive-only (TVRO) antenna? The thing is 10' diameter and it's mine for the price of dismantling it and hauling it out of the present owner's back yard. First thing that comes to my mind is EME. Ed K7AAT |
Uses for a TVRO dish antenna?
"Dave Typinski" wrote in message ... On Sun, 21 Oct 2007 11:39:12 +0100, Highland Ham wrote: Dave Typinski wrote: Anyone have any ideas about what one might do with a television receive-only (TVRO) antenna? The thing is 10' diameter and it's mine for the price of dismantling it and hauling it out of the present owner's back yard. I'm thinking radio astronomy. Might be nice to make my own radio map of the galaxy. I'm guessing that this would work okay somewhere between 1 and 10 GHz... which means making a feed horn... which is easy enough to do. What else could I do with this antenna? Other than covering it in polyethylene sheet to make a really big bird bath... ================================== Possible usage: 1) EME amateur comms 2) WiFi low power experiments (provided there is line of sight freedom) I remember having seen a web site with reports (incl photographs) that some youngsters bridged a 125 km path using off the shelf equipment and dishes having a size like yours. Hopefully you don't have just the dish but also a mounting pedestal and perhaps even a motorised system . Frank GM0CSZ / KN6WH Yep, got the pedestal and the azimuth drive motor. 125 km at 2.4 GHz? How's that work? What were they bouncing the signal off of? That's definitely further than line of sight. -- Dave Typinski AJ4CO Hi, here is link: http://hardware.slashdot.org/article...13218&from=rss |
Uses for a TVRO dish antenna?
"Dave Typinski" wrote in message ... On Sun, 21 Oct 2007 16:48:28 GMT, "Jerry Martes" wrote: "Dave Typinski" wrote in message . .. Anyone have any ideas about what one might do with a television receive-only (TVRO) antenna? The thing is 10' diameter and it's mine for the price of dismantling it and hauling it out of the present owner's back yard. I'm thinking radio astronomy. Might be nice to make my own radio map of the galaxy. I'm guessing that this would work okay somewhere between 1 and 10 GHz... which means making a feed horn... which is easy enough to do. What else could I do with this antenna? Other than covering it in polyethylene sheet to make a really big bird bath... -- Dave Typinski AJ4CO Hi Dave NOAAPORT uses a satellite over the Equator, South of Texas to transmit satellite images in near Real Time. You can easily build a station for displaying good images of the Florida as seen from space. Jerry Now /that/ would be a cool project! Thanks, Jerry. -- Dave Typinski AJ4CO http://hardware.slashdot.org/article.../09/23/1233219 |
Uses for a TVRO dish antenna?
Dave Typinski ) writes:
On Sun, 21 Oct 2007 01:01:19 -0400, "Jimmie D" wrote: "Dave Typinski" wrote in message . .. Anyone have any ideas about what one might do with a television receive-only (TVRO) antenna? The thing is 10' diameter and it's mine for the price of dismantling it and hauling it out of the present owner's back yard. I'm thinking radio astronomy. Might be nice to make my own radio map of the galaxy. I'm guessing that this would work okay somewhere between 1 and 10 GHz... which means making a feed horn... which is easy enough to do. What else could I do with this antenna? Other than covering it in polyethylene sheet to make a really big bird bath... -- Dave Typinski AJ4CO I know of a couple of guys that took two of them, one for rx and one for tx, tx was a microwave oven mgnetron. He and his frined talked to each other via troposcatter. I do know if a maggie operates within a ham band or not but it didnt matter too much for these guys because they didnt have a ticket anyway. Jimmie I thought about magnetrons... but not for communication. My idea is to set it up as a radar station to measure the distance to the Moon. A microwave oven magnetron operates at 2450 MHz, which is right at the upper edge of the 13cm ham band. Unfortunately, magnetrons produce a really dirty, wide output. Worse, being right at the edge of the band, half the RF energy would be out of band. How do you think the higher bands were conquered? It was always with simple equipment that was cheap and easy (relative speaking), with the more serious work coming later. So before WWII, it was modulated oscillators and superregen receivers on 56MHz and 112MHz. After the war, new equipment was available, and there was a desire for pushing the limits (and laws came in at some point to require better signals), and there was a move to crystal controlled transmitters and better receivers. Well, they really went together, since if you changed one, the other had to follow. So that equipment got pushed up further, helping to stake out 220MHz and 420MHz. A lot of work was done on the 1215MHz band after WWII and even through the early sixties with the venerable APX/6 (I suddenly realize I may have gotten that wrong), which was a modulated oscillator for the transmitter, and it was often debated whether it was amplitude of requency modulated. The receiver was a superhet, but had a nice broad IF bandwidth, so it didn't matter how much the transmitter drifted. I seem to recall that the APX/6 was intended as an IFF unit, it gets triggered by radar and identifies itself as a friend, so nobody shoots at the airplane. Newer techniques came along, more desire to push the limits, and that sort of thing was slowly phased out on the band. But hey, it moved further up. In the late seventies, a lot of hams played with the 10,000MHz, using garage door openers, modulated oscillators and broadband receivers. The further you go up in frequency, the more such cheap and simple equipment can be tolerated, since the bands get wider (well, until they get narrowed as bits are allocated away from amateur radio). So there is long history of both wideband simple equipment and narrowband DX'ing going on at the same time, albeit at opposite ends of the band. But in reality, you dig up that article that was in "73" years ago that was about adding a phase locked loop to a microwave oven, which gives a nice narrow signal. Michael VE2BVW |
Uses for a TVRO dish antenna?
On Sun, 21 Oct 2007 17:07:10 -0400, "Bob"
wrote: "Dave Typinski" wrote in message .. . On Sun, 21 Oct 2007 11:39:12 +0100, Highland Ham wrote: Dave Typinski wrote: Anyone have any ideas about what one might do with a television receive-only (TVRO) antenna? The thing is 10' diameter and it's mine for the price of dismantling it and hauling it out of the present owner's back yard. I'm thinking radio astronomy. Might be nice to make my own radio map of the galaxy. I'm guessing that this would work okay somewhere between 1 and 10 GHz... which means making a feed horn... which is easy enough to do. What else could I do with this antenna? Other than covering it in polyethylene sheet to make a really big bird bath... ================================== Possible usage: 1) EME amateur comms 2) WiFi low power experiments (provided there is line of sight freedom) I remember having seen a web site with reports (incl photographs) that some youngsters bridged a 125 km path using off the shelf equipment and dishes having a size like yours. Hopefully you don't have just the dish but also a mounting pedestal and perhaps even a motorised system . Frank GM0CSZ / KN6WH Yep, got the pedestal and the azimuth drive motor. 125 km at 2.4 GHz? How's that work? What were they bouncing the signal off of? That's definitely further than line of sight. -- Dave Typinski AJ4CO Hi, here is link: http://hardware.slashdot.org/article...13218&from=rss Aha! Living in Florida for the last 15 years has made me forget about the mountains out west. Yes, you can definitely go line of sight up to a few hundred miles if you have at your disposal an assortment of mile-high piles of rocks upon which to mount the antennas. http://www.wifi-toys.com/wi-fi.php?a=articles&id=91 -- Dave Typinski AJ4CO |
Uses for a TVRO dish antenna?
On Sun, 21 Oct 2007 18:15:48 GMT, "Jerry Martes"
wrote: "Dave Typinski" wrote in message .. . On Sun, 21 Oct 2007 16:48:28 GMT, "Jerry Martes" wrote: "Dave Typinski" wrote in message ... Anyone have any ideas about what one might do with a television receive-only (TVRO) antenna? The thing is 10' diameter and it's mine for the price of dismantling it and hauling it out of the present owner's back yard. I'm thinking radio astronomy. Might be nice to make my own radio map of the galaxy. I'm guessing that this would work okay somewhere between 1 and 10 GHz... which means making a feed horn... which is easy enough to do. What else could I do with this antenna? Other than covering it in polyethylene sheet to make a really big bird bath... -- Dave Typinski AJ4CO Hi Dave NOAAPORT uses a satellite over the Equator, South of Texas to transmit satellite images in near Real Time. You can easily build a station for displaying good images of the Florida as seen from space. Jerry Now /that/ would be a cool project! Thanks, Jerry. -- Dave Typinski AJ4CO Hi Dave If you do build a system for receiving the NOAAPORT images, please keep me informed about your progress. I too got my dish free. The PCI card TV receiver was low cost. The rest is computer and software. eBay is a good source of very good antenna parts at low cost. I am presently stuck due to my poor Linux skills, and Linux is used by the guys who write the software (free). Jerry I briefly went over the NOAAPORT web site. Looks like they have a Windows flavor for the software, or maybe that's just a port to a version that runs under a Windows emulator for Linux. Dunno. The site wasn't too user-friendly - which just makes me want to build the thing even more. If you have any other online references handy for this project, I'd be much obliged if you'd post them. For instance, in my review of the site, I didn't notice anything about having to use a video capture / TV tuner card - although I do have a USB version of one of those. I shall post my progress, if and when. It's a project that's not at the top of the list. First up is launching a weather balloon to 100,000 feet with a camera and a few sensors. Thanks, Jerry. -- Dave Typinski AJ4CO |
Uses for a TVRO dish antenna?
"Dave Typinski" wrote in message ... On Sun, 21 Oct 2007 18:15:48 GMT, "Jerry Martes" wrote: "Dave Typinski" wrote in message . .. On Sun, 21 Oct 2007 16:48:28 GMT, "Jerry Martes" wrote: "Dave Typinski" wrote in message m... Anyone have any ideas about what one might do with a television receive-only (TVRO) antenna? The thing is 10' diameter and it's mine for the price of dismantling it and hauling it out of the present owner's back yard. I'm thinking radio astronomy. Might be nice to make my own radio map of the galaxy. I'm guessing that this would work okay somewhere between 1 and 10 GHz... which means making a feed horn... which is easy enough to do. What else could I do with this antenna? Other than covering it in polyethylene sheet to make a really big bird bath... -- Dave Typinski AJ4CO Hi Dave NOAAPORT uses a satellite over the Equator, South of Texas to transmit satellite images in near Real Time. You can easily build a station for displaying good images of the Florida as seen from space. Jerry Now /that/ would be a cool project! Thanks, Jerry. -- Dave Typinski AJ4CO Hi Dave If you do build a system for receiving the NOAAPORT images, please keep me informed about your progress. I too got my dish free. The PCI card TV receiver was low cost. The rest is computer and software. eBay is a good source of very good antenna parts at low cost. I am presently stuck due to my poor Linux skills, and Linux is used by the guys who write the software (free). Jerry I briefly went over the NOAAPORT web site. Looks like they have a Windows flavor for the software, or maybe that's just a port to a version that runs under a Windows emulator for Linux. Dunno. The site wasn't too user-friendly - which just makes me want to build the thing even more. If you have any other online references handy for this project, I'd be much obliged if you'd post them. For instance, in my review of the site, I didn't notice anything about having to use a video capture / TV tuner card - although I do have a USB version of one of those. I shall post my progress, if and when. It's a project that's not at the top of the list. First up is launching a weather balloon to 100,000 feet with a camera and a few sensors. Thanks, Jerry. -- Dave Typinski AJ4CO Hi Dave Hector has most of what is needed to make a low cost PCI TV receiver work for NOAAPORT. The Twinhan PCI cards are affordable thru eBay and etc. I thought I'd get more help from the "regulars" on the Yahoo NOAAPORT site, but am now disappointed. And, I am slow to learn the Linux (Fedora) that is used to reduce the data. I want you to learn how to make images so you can teach me. I did go out and buy parts and assembled a computer for Fedora. Now I have to learn how to navigate in it. I too have found the"instructions" a bit difficult for me to understand. But, Hector's instructions (http://www.hwic.net/projects/weather/noaaport/) are quite direct and easy to understand. Jerry |
Uses for a TVRO dish antenna?
Dave Typinski wrote:
On Sun, 21 Oct 2007 01:01:19 -0400, "Jimmie D" wrote: "Dave Typinski" wrote in message . .. Anyone have any ideas about what one might do with a television receive-only (TVRO) antenna? The thing is 10' diameter and it's mine for the price of dismantling it and hauling it out of the present owner's back yard. I'm thinking radio astronomy. Might be nice to make my own radio map of the galaxy. I'm guessing that this would work okay somewhere between 1 and 10 GHz... which means making a feed horn... which is easy enough to do. What else could I do with this antenna? Other than covering it in polyethylene sheet to make a really big bird bath... -- Dave Typinski AJ4CO I know of a couple of guys that took two of them, one for rx and one for tx, tx was a microwave oven mgnetron. He and his frined talked to each other via troposcatter. I do know if a maggie operates within a ham band or not but it didnt matter too much for these guys because they didnt have a ticket anyway. Jimmie I thought about magnetrons... but not for communication. My idea is to set it up as a radar station to measure the distance to the Moon. A microwave oven magnetron operates at 2450 MHz, which is right at the upper edge of the 13cm ham band. Unfortunately, magnetrons produce a really dirty, wide output. Worse, being right at the edge of the band, half the RF energy would be out of band. Just how precise a measurement do you want to make? You could do quite well using a 100W 2m SSB rig and a decent yagi antenna and some signal processing software. See, e.g. http://home.earthlink.net/~n5bf/eme2.html I don't know if one can re-tune a magnetron by the addition of external components; I'd like to get the thing down to 2.42 GHz to put the emission in the center of the 13cm band. There are such things as tunable magnetrons; but, they aren't found in microwave ovens, which means they won't likely be had for free. That said, I'd sure like to look at the output from an oven magnetron with a spectrum analyzer. Maybe the output isn't as dirty and wide as I think it is. it is quite dirty, even more so in an oven because: 1) it's fed by a half wave voltage doubler, so it's pulsed at line frequency 2) the voltage waveform is hardly nice and regulated 3) the temperature of the tube changes during operation Why not build/buy some small no-tune transverters for 3.4 or 5.7 GHz and use those. At least then, you can do coherent processing over some reasonable time span, and what you lose in raw pulse power, you pick up in processing gain. The beamwidth of your 10ft dish at 2.4 GHz is going to be pretty wide, so you're illuminating a lot more than the moon (which is wasted power). In absolute terms, on receive, the fraction of the signal power received from that power which hits the moon will be the same (same physical aperture.. gain in dBi is larger, but that's just because an isotrope has smaller aperture at higher frequencies). So, your goal should be to illuminate JUST the moon (and a bit more to cover pointing errors). Beamwidth is approximately = 70*wavelength/d. So GHz m deg dBi 2.4 0.125 2.9 35 3.4 0.088 2.0 38 5.7 0.053 1.2 43 Given that you want to light up the moon with the same power, at 2.4 GHz it will take 8 dB more than 5.7 GHz. Since the moon is about 1/2 degree wide, even 5.7 GHz is a bit low for a 10 foot reflector. There's a little more than this to the whole problem, but, in general, if what you want to do is measure the distance to the moon, a radar built with an oven magnetron probably isn't the best way to go about doing it. |
Uses for a TVRO dish antenna?
Dave Typinski wrote:
On Sun, 21 Oct 2007 11:39:12 +0100, Highland Ham wrote: Dave Typinski wrote: Anyone have any ideas about what one might do with a television receive-only (TVRO) antenna? The thing is 10' diameter and it's mine for the price of dismantling it and hauling it out of the present owner's back yard. I'm thinking radio astronomy. Might be nice to make my own radio map of the galaxy. I'm guessing that this would work okay somewhere between 1 and 10 GHz... which means making a feed horn... which is easy enough to do. What else could I do with this antenna? Other than covering it in polyethylene sheet to make a really big bird bath... ================================== Possible usage: 1) EME amateur comms 2) WiFi low power experiments (provided there is line of sight freedom) I remember having seen a web site with reports (incl photographs) that some youngsters bridged a 125 km path using off the shelf equipment and dishes having a size like yours. Hopefully you don't have just the dish but also a mounting pedestal and perhaps even a motorised system . Frank GM0CSZ / KN6WH Yep, got the pedestal and the azimuth drive motor. 125 km at 2.4 GHz? How's that work? What were they bouncing the signal off of? That's definitely further than line of sight. Not if the two endpoints are up on mountains.... |
Uses for a TVRO dish antenna?
On Mon, 22 Oct 2007 10:02:57 -0700, Jim Lux
wrote: Dave Typinski wrote: On Sun, 21 Oct 2007 01:01:19 -0400, "Jimmie D" wrote: "Dave Typinski" wrote in message ... Anyone have any ideas about what one might do with a television receive-only (TVRO) antenna? The thing is 10' diameter and it's mine for the price of dismantling it and hauling it out of the present owner's back yard. I'm thinking radio astronomy. Might be nice to make my own radio map of the galaxy. I'm guessing that this would work okay somewhere between 1 and 10 GHz... which means making a feed horn... which is easy enough to do. What else could I do with this antenna? Other than covering it in polyethylene sheet to make a really big bird bath... -- Dave Typinski AJ4CO I know of a couple of guys that took two of them, one for rx and one for tx, tx was a microwave oven mgnetron. He and his frined talked to each other via troposcatter. I do know if a maggie operates within a ham band or not but it didnt matter too much for these guys because they didnt have a ticket anyway. Jimmie I thought about magnetrons... but not for communication. My idea is to set it up as a radar station to measure the distance to the Moon. A microwave oven magnetron operates at 2450 MHz, which is right at the upper edge of the 13cm ham band. Unfortunately, magnetrons produce a really dirty, wide output. Worse, being right at the edge of the band, half the RF energy would be out of band. Just how precise a measurement do you want to make? You could do quite well using a 100W 2m SSB rig and a decent yagi antenna and some signal processing software. See, e.g. http://home.earthlink.net/~n5bf/eme2.html I don't know if one can re-tune a magnetron by the addition of external components; I'd like to get the thing down to 2.42 GHz to put the emission in the center of the 13cm band. There are such things as tunable magnetrons; but, they aren't found in microwave ovens, which means they won't likely be had for free. That said, I'd sure like to look at the output from an oven magnetron with a spectrum analyzer. Maybe the output isn't as dirty and wide as I think it is. it is quite dirty, even more so in an oven because: 1) it's fed by a half wave voltage doubler, so it's pulsed at line frequency 2) the voltage waveform is hardly nice and regulated 3) the temperature of the tube changes during operation Why not build/buy some small no-tune transverters for 3.4 or 5.7 GHz and use those. At least then, you can do coherent processing over some reasonable time span, and what you lose in raw pulse power, you pick up in processing gain. A nice idea, thank you. The beamwidth of your 10ft dish at 2.4 GHz is going to be pretty wide, so you're illuminating a lot more than the moon (which is wasted power). In absolute terms, on receive, the fraction of the signal power received from that power which hits the moon will be the same (same physical aperture.. gain in dBi is larger, but that's just because an isotrope has smaller aperture at higher frequencies). So, your goal should be to illuminate JUST the moon (and a bit more to cover pointing errors). Beamwidth is approximately = 70*wavelength/d. So GHz m deg dBi 2.4 0.125 2.9 35 3.4 0.088 2.0 38 5.7 0.053 1.2 43 Given that you want to light up the moon with the same power, at 2.4 GHz it will take 8 dB more than 5.7 GHz. Since the moon is about 1/2 degree wide, even 5.7 GHz is a bit low for a 10 foot reflector. Thanks a bunch for pointing that out. I'd wondered about the relationship between beam width, reflector diameter, and frequency. Now that I think about it, doesn't focal length or focal ratio play a part as well? I don't suppose you could point me at a decent reference for this stuff, could you? I've found that Google (i.e., the web) is somewhat lacking when it comes to explanations - especially accurate ones - of where those nifty approximation equations come from. There's a little more than this to the whole problem, but, in general, if what you want to do is measure the distance to the moon, a radar built with an oven magnetron probably isn't the best way to go about doing it. So noted. The goal here is not so much to do it the best way possible, but rather to see what kind of results I can obtain using the scrap (i.e., free) materials I have available. If I were after accuracy, I'd point a laser at the corner reflectors left by the Apollo missions. 8^) -- Dave Typinski AJ4CO |
Uses for a TVRO dish antenna?
Thanks a bunch for pointing that out. I'd wondered about the relationship between beam width, reflector diameter, and frequency. Now that I think about it, doesn't focal length or focal ratio play a part as well? I don't suppose you could point me at a decent reference for this stuff, could you? I've found that Google (i.e., the web) is somewhat lacking when it comes to explanations - especially accurate ones - of where those nifty approximation equations come from. Depends on the level of detail and backup you want. There's a EW Handbook at Point Mugu Naval Air Station, you might be able to find it with google. W1GHZs online book is at: http://www.w1ghz.org/antbook/preface.htm There's a little more than this to the whole problem, but, in general, if what you want to do is measure the distance to the moon, a radar built with an oven magnetron probably isn't the best way to go about doing it. So noted. The goal here is not so much to do it the best way possible, but rather to see what kind of results I can obtain using the scrap (i.e., free) materials I have available. Sure, I understand.. It's just that MO Magnetrons are such ragged edge cost sensitive items that they spend absolutely nothing on making them good transmitter components. After all, all they have to do is heat stuff, cheaply. Even if you have a design from, say, 20-30 years ago, I suspect that modern tubes aren't going to be as suitable. I did see a clever design where they took a whole array of MO magnetrons and injection locked them to build a microwave weed killer. Microwave Journal, October 2005. http://www.mwjournal.com/journal/art...p?HH_ID=AR_113 Enjoy... If I were after accuracy, I'd point a laser at the corner reflectors left by the Apollo missions. 8^) Hmmm.. That's a nontrivial thing.. BUT, you could do (maybe the first) optical EME contact on the 470 THz band. |
Uses for a TVRO dish antenna?
Here are two sites that might be of interest to you...
http://www.wa1mba.org/ http://www.w1ghz.org/ and the link here to the online microwave antenna book provides some good reading. Scott Dave Typinski wrote: I don't suppose you could point me at a decent reference for this stuff, could you? I've found that Google (i.e., the web) is somewhat lacking when it comes to explanations - especially accurate ones - of where those nifty approximation equations come from. |
Uses for a TVRO dish antenna?
"Dave Typinski" wrote in message ... snip 125 km at 2.4 GHz? How's that work? What were they bouncing the signal off of? That's definitely further than line of sight. -- Dave Typinski AJ4CO Our local microwave hams like mountaintops. Kansas microwave hams, not so much. "Sal" (California) |
Uses for a TVRO dish antenna?
And up North, we like rain scatter...
Scott N0EDV Sal M. Onella wrote: "Dave Typinski" wrote in message ... snip 125 km at 2.4 GHz? How's that work? What were they bouncing the signal off of? That's definitely further than line of sight. -- Dave Typinski AJ4CO Our local microwave hams like mountaintops. Kansas microwave hams, not so much. "Sal" (California) -- Scott http://corbenflyer.tripod.com/ Gotta Fly or Gonna Die Building RV-4 (Super Slow Build Version) |
Uses for a TVRO dish antenna?
Just think of the salads that you could make in that giant salad bowl!!! G Ed, NM2K |
Uses for a TVRO dish antenna?
What are you expecting for birds? Condors?? The old TVRO dishes were for
2-4 ghz I think. If you used it for 10 ghz work it would have incredible gain. The surface would have to be extremely smooth as even minor imperfections woulg be bad for 10 ghz use. I saw an article that a group used a 10' 1nd a 12' dish to go 125 miles over the desert with 802.11b wireless (wireless computer network if you're not a computer person like myself). I have a smaller 4'x6' dish I want to mount on my tower someday so I can screw around on the microwave bands. I live on a mountaintop in Vermont which makes it easier to get out on the upper bands that way. Have fun with it and don't stop dreaming of the possibilities. 73's de KA1LHZ Dave Typinski wrote: Anyone have any ideas about what one might do with a television receive-only (TVRO) antenna? The thing is 10' diameter and it's mine for the price of dismantling it and hauling it out of the present owner's back yard. I'm thinking radio astronomy. Might be nice to make my own radio map of the galaxy. I'm guessing that this would work okay somewhere between 1 and 10 GHz... which means making a feed horn... which is easy enough to do. What else could I do with this antenna? Other than covering it in polyethylene sheet to make a really big bird bath... |
Uses for a TVRO dish antenna?
Jim Lux wrote:
Dave Typinski wrote: On Sun, 21 Oct 2007 01:01:19 -0400, "Jimmie D" wrote: "Dave Typinski" wrote in message ... Anyone have any ideas about what one might do with a television receive-only (TVRO) antenna? The thing is 10' diameter and it's mine for the price of dismantling it and hauling it out of the present owner's back yard. I'm thinking radio astronomy. Might be nice to make my own radio map of the galaxy. I'm guessing that this would work okay somewhere between 1 and 10 GHz... which means making a feed horn... which is easy enough to do. What else could I do with this antenna? Other than covering it in polyethylene sheet to make a really big bird bath... -- Dave Typinski AJ4CO I know of a couple of guys that took two of them, one for rx and one for tx, tx was a microwave oven mgnetron. He and his frined talked to each other via troposcatter. I do know if a maggie operates within a ham band or not but it didnt matter too much for these guys because they didnt have a ticket anyway. Jimmie I thought about magnetrons... but not for communication. My idea is to set it up as a radar station to measure the distance to the Moon. A microwave oven magnetron operates at 2450 MHz, which is right at the upper edge of the 13cm ham band. Unfortunately, magnetrons produce a really dirty, wide output. Worse, being right at the edge of the band, half the RF energy would be out of band. Just how precise a measurement do you want to make? You could do quite well using a 100W 2m SSB rig and a decent yagi antenna and some signal processing software. See, e.g. http://home.earthlink.net/~n5bf/eme2.html I don't know if one can re-tune a magnetron by the addition of external components; I'd like to get the thing down to 2.42 GHz to put the emission in the center of the 13cm band. There are such things as tunable magnetrons; but, they aren't found in microwave ovens, which means they won't likely be had for free. That said, I'd sure like to look at the output from an oven magnetron with a spectrum analyzer. Maybe the output isn't as dirty and wide as I think it is. it is quite dirty, even more so in an oven because: 1) it's fed by a half wave voltage doubler, so it's pulsed at line frequency 2) the voltage waveform is hardly nice and regulated 3) the temperature of the tube changes during operation Why not build/buy some small no-tune transverters for 3.4 or 5.7 GHz and use those. At least then, you can do coherent processing over some reasonable time span, and what you lose in raw pulse power, you pick up in processing gain. The beamwidth of your 10ft dish at 2.4 GHz is going to be pretty wide, so you're illuminating a lot more than the moon (which is wasted power). In absolute terms, on receive, the fraction of the signal power received from that power which hits the moon will be the same (same physical aperture.. gain in dBi is larger, but that's just because an isotrope has smaller aperture at higher frequencies). So, your goal should be to illuminate JUST the moon (and a bit more to cover pointing errors). Beamwidth is approximately = 70*wavelength/d. So GHz m deg dBi 2.4 0.125 2.9 35 3.4 0.088 2.0 38 5.7 0.053 1.2 43 Given that you want to light up the moon with the same power, at 2.4 GHz it will take 8 dB more than 5.7 GHz. Since the moon is about 1/2 degree wide, even 5.7 GHz is a bit low for a 10 foot reflector. There's a little more than this to the whole problem, but, in general, if what you want to do is measure the distance to the moon, a radar built with an oven magnetron probably isn't the best way to go about doing it. It's probably cheaper than buying a tape measure long enough to do the trick... KA1LHZ |
Uses for a TVRO dish antenna?
There's a little more than this to the whole problem, but, in general, if what you want to do is measure the distance to the moon, a radar built with an oven magnetron probably isn't the best way to go about doing it. Nobody asked me, but fooling around with oven magnetrons is potentially life threatening, since they are properly shielded only when installed as designed. What's cookin' might be _you_! Most in this group know that, so I'm throwing out the caution for the possible newbie. (There was a rumor years ago about a guy who damaged his internal organs trying to use a magnetron as the LO for a homebrew TVRO satellite downconverter. I looked hard and could not find any sustantiation.) |
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