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Has anyone ever designed a SW transmission system using curtan arrays that has a beamwidth of 2.5 to 5 degrees?
Has anyone ever designed a SW transmission system using curtain arrays that
has a beamwidth of 2.5 to 5 degrees? Most standard curtain arrays [HR 4/4/1 to 12/6/1] have 15 to 30 degrees of beamwidth. |
I don't know what a curtain array is for SW (Shortwave)
Transmitting.Perhaps someone else has more information. cuhulin |
Has anyone ever designed a SW transmission system using
curtain arrays that has a beamwidth of 2.5 to 5 degrees? I'd guess that if it were done, it would've been inspired by the cold-war broadcaster vs jammer "contests". If you can find pictures of antenna farms from the 50's/60's/70's (sometimes pictured on QSL cards for example) you might look for patterns indicative of the arrays you're interested in. Tim. |
Curtain Array - Last picture in the series.. http://www.xs4all.nl/~gouwelee/pj4pa2vst.htm - ALSO.. heard on WBCQ that there is someone in Florida who made their antenna(s) Check around.. |
Max Power,
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Bonaire,looks like a nice place.I didn't know those kinds of antennas
are called curtain antennas,but I have seen them before in movies and books and magazines. cuhulin |
Max Power wrote in message ... Has anyone ever designed a SW transmission system using curtain arrays that has a beamwidth of 2.5 to 5 degrees? Most standard curtain arrays [HR 4/4/1 to 12/6/1] have 15 to 30 degrees of beamwidth. Talk about the curtain array... that brings to mind a somewhat recent class I took, that of all students attending, there was the daughter of a VOA engineer responsible for rebuilding a number of stations; she was in my study group and what a nitwit! I played dumb and never let on I knew anything about shortwave broadcast stations or the pecuilar circumstances and delicate political situation regarding one of her father's constructions. RG |
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"Max Power" wrote in message
... Has anyone ever designed a SW transmission system using curtain arrays that has a beamwidth of 2.5 to 5 degrees? Most standard curtain arrays [HR 4/4/1 to 12/6/1] have 15 to 30 degrees of beamwidth. It's gonna be big! A 3 meter diameter dish at 4 GHz has a beanwidth of 1.75 degrees. Scale that to 4 MHz and it will need a diameter of 3 kilometers. For 5 degree beamwidth, probably about 1 kilometer diameter for 4 MHz, and 400 meter diameter at 10 MHz. An array will have similar dimensions for similar results. Tom |
What the hell! What is in the water over there in Colliersville anyway?
I am going to sic all of them mean old Pitt Bulldogs on you.Hey,I don't know everything about Shortwave Radio and Shortwave Antennas and Shortwave Transmitters.I do know what Curtain Antennas are now though.Sheeesh!,,,y'all Tennesseans sure are dense! Memphians don't like Mississippians either.Those Alabama Dumb Asses are far better than y'all Tennesseans and so are those Louisiana Cajun Coon Asses too.I suppose you have always all your life known what Curtain Antennas/Transmitters are eh? Every since the day you was born! cuhulin |
My eight years older brother was an MP over fifty years ago.I have every
right in the World to read alt.military.police news group and post there any time I feel like it.I guess you have a problem with that too,eh? cuhulin |
George Ashley,and then my eight years older brother got in Helicopter
Maintnance.He was a Helicopter Mechanic at Vung Tau,Vietnam in 1964 (his second Tour of Duty in Vietnam following a year in Germany) the same year I was in Vietnam too,in 1964.YOU are the DUMBIST SON OF A BITCH!!!!! IN THE WORLD!!!! cuhulin |
"Tom Holden" wrote in message .. . "Max Power" wrote in message ... Has anyone ever designed a SW transmission system using curtain arrays that has a beamwidth of 2.5 to 5 degrees? Most standard curtain arrays [HR 4/4/1 to 12/6/1] have 15 to 30 degrees of beamwidth. It's gonna be big! A 3 meter diameter dish at 4 GHz has a beanwidth of 1.75 degrees. Scale that to 4 MHz and it will need a diameter of 3 kilometers. For 5 degree beamwidth, probably about 1 kilometer diameter for 4 MHz, and 400 meter diameter at 10 MHz. An array will have similar dimensions for similar results. Tom An excellent analogy Tom. Narrower beamwidths come about as a result of increased gain. Increased gain comes from larger arrays. Those kinds of beamwidths are practical at microwave freqs, not HF. The gain of the 1M dish (2.5 degree conical beamwidth) at 4 GHz is around 40dBi. A rough esrtimate tells me an array of 4000-8000 1 wavelength dipoles could achieve this. Then again, I could be wrong. Dale W4OP |
On Wed, 06 Apr 2005 02:52:41 GMT, "Dale Parfitt"
wrote: "Tom Holden" wrote in message . .. "Max Power" wrote in message ... Has anyone ever designed a SW transmission system using curtain arrays that has a beamwidth of 2.5 to 5 degrees? Most standard curtain arrays [HR 4/4/1 to 12/6/1] have 15 to 30 degrees of beamwidth. It's gonna be big! A 3 meter diameter dish at 4 GHz has a beanwidth of 1.75 degrees. Scale that to 4 MHz and it will need a diameter of 3 kilometers. For 5 degree beamwidth, probably about 1 kilometer diameter for 4 MHz, and 400 meter diameter at 10 MHz. An array will have similar dimensions for similar results. Tom An excellent analogy Tom. Narrower beamwidths come about as a result of increased gain. Increased gain comes from larger arrays. Those kinds of beamwidths are practical at microwave freqs, not HF. The gain of the 1M dish (2.5 degree conical beamwidth) at 4 GHz is around 40dBi. A rough esrtimate tells me an array of 4000-8000 1 wavelength dipoles could achieve this. Then again, I could be wrong. Dale W4OP Well, our Telefunken curtain arrays have a typical gain of 20-23 dB. TeleSource has just installed two TCI (Technology for Communications International) 611VS curtains at 270 and 305 degrees for the low band (6-12 MHz) here on Tinian. 3db azimuthal beamwidth is variable between 20-36 degrees, and they are vertically slewable in 4x4 and 4x6 mode. Gain is between 16.6 to 24.1 dBi, and tower height is about 470 feet. I would daresay if a 3-5 degree beamwidth had ever been made, it is probably experimental. The physical size makes it prohibitively expensive as well as mechanically improbable. Al in CNMI IBB Station engineer (contract) ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups ----= East and West-Coast Server Farms - Total Privacy via Encryption =---- |
I sort of know a guy in Hattiesburg,Mississippi.He is about 73 years old
and he was at Kagnew Station in Africa. www.kagnewstation.com He worked in decyphering radio signals at Kagnew Station,U.S.Army.I bet they had a really good radio and antenna setup there. cuhulin |
"Dale Parfitt" wrote:
A rough esrtimate tells me an array of 4000-8000 1 wavelength dipoles could achieve this. Heh. I'd like to see the phasing harness! |
Not likely. Such an array would be about twenty wavelengths wide (and still
have reasonable side lobes). It is improbable that one could keep the required elements' current close enough in phase to be able to realize a 2.5 degree beamwidth. Too expensive. If used on a path that is longer than something like 10Mm, the narrow beam will occasionally miss the target (unless one adds skewing, which would be expensive in this case). In other words, a SW broadcast system would not want such an antenna. Less expensive and more reliable to buy a larger transmitter. Why do you ask? Mac N8TT -- J. Mc Laughlin; Michigan U.S.A. Home: "Max Power" wrote in message ... Has anyone ever designed a SW transmission system using curtain arrays that has a beamwidth of 2.5 to 5 degrees? Most standard curtain arrays [HR 4/4/1 to 12/6/1] have 15 to 30 degrees of beamwidth. |
"Tebojockey" wrote in message
... Well, our Telefunken curtain arrays have a typical gain of 20-23 dB. TeleSource has just installed two TCI (Technology for Communications International) 611VS curtains at 270 and 305 degrees for the low band (6-12 MHz) here on Tinian. 3db azimuthal beamwidth is variable between 20-36 degrees, and they are vertically slewable in 4x4 and 4x6 mode. Gain is between 16.6 to 24.1 dBi, and tower height is about 470 feet. I would daresay if a 3-5 degree beamwidth had ever been made, it is probably experimental. The physical size makes it prohibitively expensive as well as mechanically improbable. Al in CNMI IBB Station engineer (contract) Al, impressive sounding array. I think you mean the 3-5 degree HF array could only have been scale modelled at much higher frequencies. The largest dish antenna is the Arecibo radio telescope at 305 meter (1000') diameter http://www.naic.edu/public/the_telescope.htm. That could give a 5 degree or better beamwidth above 13-15 MHz if it had a suitable antenna at the focal point. I don't know what its lowest frequency of operation might be but this page http://www.naic.edu/techinfo/prcz/prczinfo.htm indicates that 13.36 - 13.41 MHz is protected for radio astronomy. It's possible that its original use for radar back scatter studies of the Ionosphere under the DoD may have had it transmitting near the 20 meter band! With 5 degree beamwidth pointing straight up, it would take a lot of hops to make any decent terrestrial DX! Tom |
Tom Holden wrote:
I think you mean the 3-5 degree HF array could only have been scale modelled at much higher frequencies. The largest dish antenna is the Arecibo radio telescope at 305 meter (1000') diameter http://www.naic.edu/public/the_telescope.htm. That could give a 5 degree or better beamwidth above 13-15 MHz if it had a suitable antenna at the focal point. I don't know what its lowest frequency of operation might be but this page http://www.naic.edu/techinfo/prcz/prczinfo.htm indicates that 13.36 - 13.41 MHz is protected for radio astronomy. It's possible that its original use for radar back scatter studies of the Ionosphere under the DoD may have had it transmitting near the 20 meter band! With 5 degree beamwidth pointing straight up, it would take a lot of hops to make any decent terrestrial DX! Tom Has anyone here ever seen a real curtain antenna while standing underneath? I visited the old VOA plant in Mason, Ohio "Bethany" in the late '60s and got the full tour with my high school's ham radio club. Today its just another golf course for Cincinnati. -- Former professional electron wrangler. Michael A. Terrell Central Florida |
Well, our Telefunken curtain arrays have a typical gain of 20-23 dB.
TeleSource has just installed two TCI (Technology for Communications International) 611VS curtains at 270 and 305 degrees for the low band (6-12 MHz) here on Tinian. 3db azimuthal beamwidth is variable between 20-36 degrees, and they are vertically slewable in 4x4 and 4x6 mode. Gain is between 16.6 to 24.1 dBi, and tower height is about 470 feet. I would daresay if a 3-5 degree beamwidth had ever been made, it is probably experimental. The physical size makes it prohibitively expensive as well as mechanically improbable. Al in CNMI IBB Station engineer (contract) I wonder if shortwave broadcast antennas have been used for signals/communications intelligence? RG |
On Wed, 6 Apr 2005 23:19:21 -0400, "Tom Holden"
wrote: "Tebojockey" wrote in message .. . Well, our Telefunken curtain arrays have a typical gain of 20-23 dB. TeleSource has just installed two TCI (Technology for Communications International) 611VS curtains at 270 and 305 degrees for the low band (6-12 MHz) here on Tinian. 3db azimuthal beamwidth is variable between 20-36 degrees, and they are vertically slewable in 4x4 and 4x6 mode. Gain is between 16.6 to 24.1 dBi, and tower height is about 470 feet. I would daresay if a 3-5 degree beamwidth had ever been made, it is probably experimental. The physical size makes it prohibitively expensive as well as mechanically improbable. Al in CNMI IBB Station engineer (contract) Al, impressive sounding array. I think you mean the 3-5 degree HF array could only have been scale modelled at much higher frequencies. The largest dish antenna is the Arecibo radio telescope at 305 meter (1000') diameter http://www.naic.edu/public/the_telescope.htm. That could give a 5 degree or better beamwidth above 13-15 MHz if it had a suitable antenna at the focal point. I don't know what its lowest frequency of operation might be but this page http://www.naic.edu/techinfo/prcz/prczinfo.htm indicates that 13.36 - 13.41 MHz is protected for radio astronomy. It's possible that its original use for radar back scatter studies of the Ionosphere under the DoD may have had it transmitting near the 20 meter band! With 5 degree beamwidth pointing straight up, it would take a lot of hops to make any decent terrestrial DX! Tom Hey Tom, Nice to hear from you. I agree with your observations, but the problem with what you describe is the angle of incidence/angle of reflection. As you point out, the hops required would probably decimate the signal before it reached the target area. Shortwave requires a calculation of the takeoff angle (another term for incidence/reflection) so that the optimal signal arrives in the target area. If we could tilt Arecibo's antenna up on a 45 degree angle, it might have possibilities! Do we have anough men and kegs of beer to give it a whirl? LOL 73 Al in CNMI ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups ----= East and West-Coast Server Farms - Total Privacy via Encryption =---- |
On Thu, 07 Apr 2005 04:32:12 GMT, "Michael A. Terrell"
wrote: Tom Holden wrote: I think you mean the 3-5 degree HF array could only have been scale modelled at much higher frequencies. The largest dish antenna is the Arecibo radio telescope at 305 meter (1000') diameter http://www.naic.edu/public/the_telescope.htm. That could give a 5 degree or better beamwidth above 13-15 MHz if it had a suitable antenna at the focal point. I don't know what its lowest frequency of operation might be but this page http://www.naic.edu/techinfo/prcz/prczinfo.htm indicates that 13.36 - 13.41 MHz is protected for radio astronomy. It's possible that its original use for radar back scatter studies of the Ionosphere under the DoD may have had it transmitting near the 20 meter band! With 5 degree beamwidth pointing straight up, it would take a lot of hops to make any decent terrestrial DX! Tom Has anyone here ever seen a real curtain antenna while standing underneath? I visited the old VOA plant in Mason, Ohio "Bethany" in the late '60s and got the full tour with my high school's ham radio club. Today its just another golf course for Cincinnati. Michael, I see 'em everyday! LOL They're beautiful, until you have to lower one to effect repairs because the cheapskates didn't install the proper catenaries for riggers going aloft! It's a 3-day project which plays havic with the schedule.... I have a feeling IBB may be shutting down other sites in the next five years or so. It seems they feel the budget crunches more than most other agencies. Al in CNMI ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups ----= East and West-Coast Server Farms - Total Privacy via Encryption =---- |
On Thu, 07 Apr 2005 15:19:29 GMT, "RadioGuy"
wrote: Well, our Telefunken curtain arrays have a typical gain of 20-23 dB. TeleSource has just installed two TCI (Technology for Communications International) 611VS curtains at 270 and 305 degrees for the low band (6-12 MHz) here on Tinian. 3db azimuthal beamwidth is variable between 20-36 degrees, and they are vertically slewable in 4x4 and 4x6 mode. Gain is between 16.6 to 24.1 dBi, and tower height is about 470 feet. I would daresay if a 3-5 degree beamwidth had ever been made, it is probably experimental. The physical size makes it prohibitively expensive as well as mechanically improbable. Al in CNMI IBB Station engineer (contract) I wonder if shortwave broadcast antennas have been used for signals/communications intelligence? RG Back in the old days of the ASA, we had a General Dynamics FLR-9 antenna at most field stations. It was about 2km in diameter with vertical antennas for every degree. In germany, late at night, we would roll the old R-390A up on mediumwave and listen to ball games from New York. You can see a picture of one on the home page at www.usafsa.org which is Field Station Augsburg's home page. ASA Lives! Al in CNMI ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups ----= East and West-Coast Server Farms - Total Privacy via Encryption =---- |
wrote in message ... Didn't 007 once stop somebody from trying to "tilt" the Arecibo Telescope? That's wrong on so many levels that it must have set some sort of record. |
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