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#1
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Most people have added an amplifier only to find out that the
difference in signal was very small. Thus many people deride the value of a 'silly' db gain whereas DX'ers say that a single db extra is a lot ! Fact is that most long distance signals on 20 metres come in at angles of 11 degrees or less where as the 'normal' antenna has a TOA of around 14 degrees. So where a dxer points to the extra 1db gain as being everything in fact it is the lowering of the TOA that comes with the extra gain. In my opinion if one designs his antenna for a lower TOA say 10 to 11 degrees then even tho its gain may well be below the dxers choise( a very long boom or stacked antennas) the lower TOA with less gain will show little difference to the antenna of choics because the lower edge of the radiation lobe will follow the same line and any extra gain provided will have the same effect of adding an amplifier which is minimal compared to the ability of capturing signals that arrive at low angles. I believe it is time for antenna designers to concentrate less on obtaining gain and instead concentrate more on lowering the TOA. without the need of excessive real estate requirements. What say ? Art |
#2
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art wrote:
I believe it is time for antenna designers to concentrate less on obtaining gain and instead concentrate more on lowering the TOA. without the need of excessive real estate requirements. What say ? I lowered my 20m dipole from 40 ft. to 30 ft. because that gave me a better skip into Arizona where a lot of my friends are. -- 73, Cecil http://www.qsl.net/w5dxp ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= East/West-Coast Server Farms - Total Privacy via Encryption =--- |
#3
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![]() Cecil wrote - I lowered my 20m dipole from 40 ft. to 30 ft. because that gave me a better skip into Arizona where a lot of my friends are. ======================= No Cecil, it didn't. It just gave you worse skip into where you didn't want it. --- Reg |
#4
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So true ! Many a DXer loses signals because his TOA is to low
Art "Cecil Moore" wrote in message ... art wrote: I believe it is time for antenna designers to concentrate less on obtaining gain and instead concentrate more on lowering the TOA. without the need of excessive real estate requirements. What say ? I lowered my 20m dipole from 40 ft. to 30 ft. because that gave me a better skip into Arizona where a lot of my friends are. -- 73, Cecil http://www.qsl.net/w5dxp ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= East/West-Coast Server Farms - Total Privacy via Encryption =--- |
#5
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On 28 Jan 2005 12:48:52 -0800, "art" wrote:
Most people have added an amplifier only to find out that the difference in signal was very small. Thus many people deride the value of a 'silly' db gain whereas DX'ers say that a single db extra is a lot ! Fact is that most long distance signals on 20 metres come in at angles of 11 degrees or less where as the 'normal' antenna has a TOA of around 14 degrees. So where a dxer points to the extra 1db gain as being everything in fact it is the lowering of the TOA that comes with the extra gain. In my opinion if one designs his antenna for a lower TOA say 10 to 11 degrees then even tho its gain may well be below the dxers choise( a very long boom or stacked antennas) the lower TOA with less gain will show little difference to the antenna of choics because the lower edge of the radiation lobe will follow the same line and any extra gain provided will have the same effect of adding an amplifier which is minimal compared to the ability of capturing signals that arrive at low angles. I believe it is time for antenna designers to concentrate less on obtaining gain and instead concentrate more on lowering the TOA. without the need of excessive real estate requirements. What say ? Art I have always thought that if one changed the azimuth angle of a beam it would improve a number of contact signals, pending the angle they are reflected from the atmosphere. -- Buck N4PGW |
#6
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You can move the antenna boom up or down some 10 degrees and you would not
be able to tell the difference per Lawson W2PV Art "Buck" wrote in message ... On 28 Jan 2005 12:48:52 -0800, "art" wrote: Most people have added an amplifier only to find out that the difference in signal was very small. Thus many people deride the value of a 'silly' db gain whereas DX'ers say that a single db extra is a lot ! Fact is that most long distance signals on 20 metres come in at angles of 11 degrees or less where as the 'normal' antenna has a TOA of around 14 degrees. So where a dxer points to the extra 1db gain as being everything in fact it is the lowering of the TOA that comes with the extra gain. In my opinion if one designs his antenna for a lower TOA say 10 to 11 degrees then even tho its gain may well be below the dxers choise( a very long boom or stacked antennas) the lower TOA with less gain will show little difference to the antenna of choics because the lower edge of the radiation lobe will follow the same line and any extra gain provided will have the same effect of adding an amplifier which is minimal compared to the ability of capturing signals that arrive at low angles. I believe it is time for antenna designers to concentrate less on obtaining gain and instead concentrate more on lowering the TOA. without the need of excessive real estate requirements. What say ? Art I have always thought that if one changed the azimuth angle of a beam it would improve a number of contact signals, pending the angle they are reflected from the atmosphere. -- Buck N4PGW |
#7
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Jim Lawson, W2PV, solved the TOA problem on 20 M with a l o n g yagi at
~150' to open the band and his either/or/both stack(top antenna at about 70-80', as I remember) for normal band condition. Oh yes, Alpha 77s on most bands, too! Phil, KB2HQ, former neighbor of W2PV " wrote in message news:ODzKd.33178$IV5.6955@attbi_s54... You can move the antenna boom up or down some 10 degrees and you would not be able to tell the difference per Lawson W2PV Art "Buck" wrote in message ... On 28 Jan 2005 12:48:52 -0800, "art" wrote: Most people have added an amplifier only to find out that the difference in signal was very small. Thus many people deride the value of a 'silly' db gain whereas DX'ers say that a single db extra is a lot ! Fact is that most long distance signals on 20 metres come in at angles of 11 degrees or less where as the 'normal' antenna has a TOA of around 14 degrees. So where a dxer points to the extra 1db gain as being everything in fact it is the lowering of the TOA that comes with the extra gain. In my opinion if one designs his antenna for a lower TOA say 10 to 11 degrees then even tho its gain may well be below the dxers choise( a very long boom or stacked antennas) the lower TOA with less gain will show little difference to the antenna of choics because the lower edge of the radiation lobe will follow the same line and any extra gain provided will have the same effect of adding an amplifier which is minimal compared to the ability of capturing signals that arrive at low angles. I believe it is time for antenna designers to concentrate less on obtaining gain and instead concentrate more on lowering the TOA. without the need of excessive real estate requirements. What say ? Art I have always thought that if one changed the azimuth angle of a beam it would improve a number of contact signals, pending the angle they are reflected from the atmosphere. -- Buck N4PGW |
#8
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On Sat, 29 Jan 2005 13:11:20 GMT, "Phil"
wrote: Jim Lawson, W2PV, solved the TOA problem on 20 M with a l o n g yagi at ~150' to open the band and his either/or/both stack(top antenna at about 70-80', as I remember) for normal band condition. Oh yes, Alpha 77s on most bands, too! Phil, KB2HQ, former neighbor of W2PV I imagine that you had an interesting ham life when you shared the same band and he communicated in your direction. -- Buck N4PGW |
#9
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Hi Art
I'd say that every little bit helps when conditions are marginal. Even 10dB extra mean pretty well nothing in readability when the signal is already 20dB above the noise, but a few dB *can* make a difference when the signal is in noise. Antenna efficiency and gain in the right direction all helps but it is going to be a compromise. I mean if you want to chat to the "locals" 30 degrees takeoff is better again! I'll admit that I havent done any huge a amount of modelling on this but (IMO) ground conditions and height over are far more important and are very difficult to design an antenna for all situations. Maybe the trick is to design your antenna for free space for "good" gain and then be able to raise and lower it for the best angles.. Cheers Bob VK2YQA art wrote: Most people have added an amplifier only to find out that the difference in signal was very small. Thus many people deride the value of a 'silly' db gain whereas DX'ers say that a single db extra is a lot ! Fact is that most long distance signals on 20 metres come in at angles of 11 degrees or less where as the 'normal' antenna has a TOA of around 14 degrees. So where a dxer points to the extra 1db gain as being everything in fact it is the lowering of the TOA that comes with the extra gain. In my opinion if one designs his antenna for a lower TOA say 10 to 11 degrees then even tho its gain may well be below the dxers choise( a very long boom or stacked antennas) the lower TOA with less gain will show little difference to the antenna of choics because the lower edge of the radiation lobe will follow the same line and any extra gain provided will have the same effect of adding an amplifier which is minimal compared to the ability of capturing signals that arrive at low angles. I believe it is time for antenna designers to concentrate less on obtaining gain and instead concentrate more on lowering the TOA. without the need of excessive real estate requirements. What say ? Art |
#10
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![]() "Bob Bob" wrote in message news ![]() Hi Art I'd say that every little bit helps when conditions are marginal. Even 10dB extra mean pretty well nothing in readability when the signal is already 20dB above the noise, but a few dB *can* make a difference when the signal is in noise. I don't see that! would not the S/N stay the same? Antenna efficiency and gain in the right direction all helps but it is going to be a compromise. I mean if you want to chat to the "locals" 30 degrees takeoff is better again! Agreed, that is what Cecil did. I'll admit that I havent done any huge a amount of modelling on this but (IMO) ground conditions and height over are far more important and are very difficult to design an antenna for all situations. For horizontal waves the ground conditions relative to 1 wavelength is of little concern Height as always helps with low TOA so one has to determine the average incoming signal angle of choice QSO's and design to suit. Maybe the trick is to design your antenna for free space for "good" gain and then be able to raise and lower it for the best angles.. Agreed but I would like to see smaller turning radius ( moving away from the boom length mantra , ) without the necessity for dual driven stacked array This would require a fixed feed point with moveable elements for desired TOA to suit desired QSO.. I am sure it can be done, and since 'every thing is known about antennas' all that is reguired is for a Guru to come forward to share how it is done. Regards Art Cheers Bob VK2YQA art wrote: Most people have added an amplifier only to find out that the difference in signal was very small. Thus many people deride the value of a 'silly' db gain whereas DX'ers say that a single db extra is a lot ! Fact is that most long distance signals on 20 metres come in at angles of 11 degrees or less where as the 'normal' antenna has a TOA of around 14 degrees. So where a dxer points to the extra 1db gain as being everything in fact it is the lowering of the TOA that comes with the extra gain. In my opinion if one designs his antenna for a lower TOA say 10 to 11 degrees then even tho its gain may well be below the dxers choise( a very long boom or stacked antennas) the lower TOA with less gain will show little difference to the antenna of choics because the lower edge of the radiation lobe will follow the same line and any extra gain provided will have the same effect of adding an amplifier which is minimal compared to the ability of capturing signals that arrive at low angles. I believe it is time for antenna designers to concentrate less on obtaining gain and instead concentrate more on lowering the TOA. without the need of excessive real estate requirements. What say ? Art |
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