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#21
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On 27 Mar, 15:12, (Richard Harrison) wrote:
Art wrote: "I have his (Kraus`) second edition (Antennas) and I find no mention of radiation from the beginning where current is applied onward." I think I have that edition too. If you review the chapter on "Point Sources" you`ll find: power patterns, a power theorem and its application to isotropic sources, rediation intensity, source with hemispheric power pattern, unidirectional cosine power pattern, etc., etc.. snip. Being uncertain of what Art really wants, doesn`t stop me from advising snip Bingo Just as I thought, you are bull****ting like the rest of them. All you have is the answer for the question you want me to ask so you can then look good. When you give that same answer to any question that I actually ask it sure removes any possible credability. If you all had been nice to the MIT guy he may have come back and give you a tutorial again to set you straight, but I suspect he left for the same reasons that other experts left. I accept that none on the thread has a clue so it is reasonable to close down this thread to allow you to get back to badger Walt. I believe that each poster has provided an average of ten posts on Walt's article which suggest that Walt is having a bad time with communicating his message like me. My bet is that half of the posts aren't even relavent to the subject at hand! That's tough for anybody.Richard you have posted four times with lots of words on this thread but at the very end you admit that you have no idea what the thread was all about. So what were your answers meant to apply to so I can oblige you with supplying the question that you want... to the answer you have already so you can spout off. No ........forget it. ............FINI.......... Art Best regards, Richard Harrison, KB5WZI |
#22
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I readily admit I have not discovered whhat Art asked for. My first
guess was: Why are most antennas either horizontal or vertical. I tried to give a thoughtful and honest answer. Sorry it didn`t satisfy. Best regards, Richard Harrison, KB5WZI |
#23
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![]() "Richard Harrison" wrote in message ... I readily admit I have not discovered whhat Art asked for. My first guess was: Why are most antennas either horizontal or vertical. I tried to give a thoughtful and honest answer. Sorry it didn`t satisfy. Best regards, Richard Harrison, KB5WZI I looked up the references, seems good to me. Jimmie. |
#24
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#25
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On 27 Mar 2007 16:39:52 -0700, "art" wrote:
On 27 Mar, 15:12, (Richard Harrison) wrote: Art wrote: "I have his (Kraus`) second edition (Antennas) and I find no mention of radiation from the beginning where current is applied onward." I think I have that edition too. If you review the chapter on "Point Sources" you`ll find: power patterns, a power theorem and its application to isotropic sources, rediation intensity, source with hemispheric power pattern, unidirectional cosine power pattern, etc., etc.. The new, now available 3rd ed. of "Antennas" by Kraus, Marhefka, and a host of others is greatly expanded and improved. It is worth the investment. Being uncertain of what Art really wants, doesn`t stop me from advising him to start by having a look at the famous Sommerfeld formula on page 804 of Terman`s 1955 opus. It predicts 1 kilowatt will produce 186 mv per m at a distance of 1 mile from a short vertical transmitting antenna given a certain ground conductivity and other conditions. Best regards, Richard Harrison, KB5WZI Richard, I have lots of books but as yet have not found the answer even tho many have posted none appear to really have an answer other than to throw stones. You apparently have found the answer! Could you quote from the books that you are refering to the angle of radiation relative to the radiator, thats it ? If you can't understand that then relay to me the angle of a radiation front relative to a radiator, I'm sure some other people are interested in what you found. Even better, let me know the TOA of a dipole in free space and how much it varies to that of the same dipole over a perfect ground. Use a computor program if you like, anything that sheds light on the matter . The books say that a horizontal "v" antenna should be tipped for max gain, doesn't that raise your interest about the reasoning and mathematics behind this? Jimmie D asked me to state this angle but I have only a expensive computor program that doesn't give the math with the answer. Please read off the angle and the specifics so we all can move on, I don't want a 160 thread postings some thrust upon Walt Art The take-off angle of a dipole in free space? The angle with respect to what? Walt, W2DU |
#26
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On 31 Mar, 14:36, Walter Maxwell wrote:
On 27 Mar 2007 16:39:52 -0700, "art" wrote: On 27 Mar, 15:12, (Richard Harrison) wrote: Art wrote: "I have his (Kraus`) second edition (Antennas) and I find no mention of radiation from the beginning where current is applied onward." I think I have that edition too. If you review the chapter on "Point Sources" you`ll find: power patterns, a power theorem and its application to isotropic sources, rediation intensity, source with hemispheric power pattern, unidirectional cosine power pattern, etc., etc.. The new, now available 3rd ed. of "Antennas" by Kraus, Marhefka, and a host of others is greatly expanded and improved. It is worth the investment. Being uncertain of what Art really wants, doesn`t stop me from advising him to start by having a look at the famous Sommerfeld formula on page 804 of Terman`s 1955 opus. It predicts 1 kilowatt will produce 186 mv per m at a distance of 1 mile from a short vertical transmitting antenna given a certain ground conductivity and other conditions. Best regards, Richard Harrison, KB5WZI Richard, I have lots of books but as yet have not found the answer even tho many have posted none appear to really have an answer other than to throw stones. You apparently have found the answer! Could you quote from the books that you are refering to the angle of radiation relative to the radiator, thats it ? If you can't understand that then relay to me the angle of a radiation front relative to a radiator, I'm sure some other people are interested in what you found. Even better, let me know the TOA of a dipole in free space and how much it varies to that of the same dipole over a perfect ground. Use a computor program if you like, anything that sheds light on the matter . The books say that a horizontal "v" antenna should be tipped for max gain, doesn't that raise your interest about the reasoning and mathematics behind this? Jimmie D asked me to state this angle but I have only a expensive computor program that doesn't give the math with the answer. Please read off the angle and the specifics so we all can move on, I don't want a 160 thread postings some thrust upon Walt Art The take-off angle of a dipole in free space? The angle with respect to what? Walt, W2DU- Hide quoted text - - Show quoted text - Always zero Walt since it takes two dipoles to tango. |
#27
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Art wrote:
"Even better, let me know the TOA of a dipole in free space and how much it varies to that of the same dipole over perfect ground." If possible, look at Terman`s1955 opus page 882: "Effect of Ground on the Directional Pattern of Ungrounded Antennas - Image Antennas." In free space, no reflecting surface is nearby to distort the pattern of a radiator. Terman gives the familiar radiation of a 1/2-wave dipole in space in Fig. 23-4(a) on page 867. Terman says on page 883: "For purposes of calculation, it is convenient to consider that the reflected wave is generated, not by reflection, but rather by an "image" antenna located below the surface of the ground." The summation of the direct and reflected waves from a horoizontal wire above the earth often has serious consequences as Terman notes on page 885: "Consequently, to obtain strong radiation in directions approaching the horizontal using a horizontally polarized radiating system, it is necessary that the height of the antenna above the earth be in the order of one wavelength or more." Terman shows the vertical radiation patterns for a horizontal wire at various heights above the earth in Fig. 23-21 on page 884. Note that half-wave elevation concentrates most energy into a good elevation angle for sky wave reflection at some frequencies and distances. Best regards, Richard Harrison, KB5WZI |
#28
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Art wrote:
"Even better, let me know the TOA of a dipole in free space and how much it varies to that of the same dipole over perfect ground." If possible, look at Terman`s1955 opus page 882: "Effect of Ground on the Directional Pattern of Ungrounded Antennas - Image Antennas." In free space, no reflecting surface is nearby to distort the pattern of a radiator. Terman gives the familiar radiation of a 1/2-wave dipole in space in Fig. 23-4(a) on page 867. Terman says on page 883: "For purposes of calculation, it is convenient to consider that the reflected wave is generated, not by reflection, but rather by an "image" antenna located below the surface of the ground." The summation of the direct and reflected waves from a horoizontal wire above the earth often has serious consequences as Terman notes on page 885: "Consequently, to obtain strong radiation in directions approaching the horizontal using a horizontally polarized radiating system, it is necessary that the height of the antenna above the earth be in the order of one wavelength or more." Terman shows the vertical radiation patterns for a horizontal wire at various heights above the earth in Fig. 23-21 on page 884. Note that half-wave elevation concentrates most energy into a good elevation angle for sky wave reflection at some frequencies and distances. Best regards, Richard Harrison, KB5WZI |
#29
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On 1 Apr, 09:34, (Richard Harrison) wrote:
Art wrote: "Even better, let me know the TOA of a dipole in free space and how much it varies to that of the same dipole over perfect ground." If possible, look at Terman`s1955 opus page 882: "Effect of Ground on the Directional Pattern of Ungrounded Antennas - Image Antennas." In free space, no reflecting surface is nearby to distort the pattern of a radiator. Terman gives the familiar radiation of a 1/2-wave dipole in space in Fig. 23-4(a) on page 867. Terman says on page 883: "For purposes of calculation, it is convenient to consider that the reflected wave is generated, not by reflection, but rather by an "image" antenna located below the surface of the ground." The summation of the direct and reflected waves from a horoizontal wire above the earth often has serious consequences as Terman notes on page 885: "Consequently, to obtain strong radiation in directions approaching the horizontal using a horizontally polarized radiating system, it is necessary that the height of the antenna above the earth be in the order of one wavelength or more." Terman shows the vertical radiation patterns for a horizontal wire at various heights above the earth in Fig. 23-21 on page 884. Note that half-wave elevation concentrates most energy into a good elevation angle for sky wave reflection at some frequencies and distances. Best regards, Richard Harrison, KB5WZI Very good, all accepted, I am now in a position to ask the real question of "why" where the starting point is acceptable to all. .. I model a dipole in free space to obtain its impedance, this dipole was resonant at right angles to the ground and resting on the ground. I also modelled another dipole over the ground and tipped it over about 5% of its WL but letting the length grow until the dipole was resonant over ground ( ground means perfect ground as per Mininec) I then placed this tipped dipole in free space and noted its impedance. In all cases the impedance in free space was the same though not resonant! In all cases over ground the dipoles were resonant. Why were both dipoles over ground resonant? Why did the program model the dipole at a tipped angle for resonance when given total freedom instead of modeling a dipole at right angles to ground? Regards Art |
#30
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![]() "art" wrote in message oups.com... On 27 Mar, 15:12, (Richard Harrison) wrote: Art wrote: "I have his (Kraus`) second edition (Antennas) and I find no mention of radiation from the beginning where current is applied onward." I think I have that edition too. If you review the chapter on "Point Sources" you`ll find: power patterns, a power theorem and its application to isotropic sources, rediation intensity, source with hemispheric power pattern, unidirectional cosine power pattern, etc., etc.. The new, now available 3rd ed. of "Antennas" by Kraus, Marhefka, and a host of others is greatly expanded and improved. It is worth the investment. Being uncertain of what Art really wants, doesn`t stop me from advising him to start by having a look at the famous Sommerfeld formula on page 804 of Terman`s 1955 opus. It predicts 1 kilowatt will produce 186 mv per m at a distance of 1 mile from a short vertical transmitting antenna given a certain ground conductivity and other conditions. Best regards, Richard Harrison, KB5WZI Richard, I have lots of books but as yet have not found the answer even tho many have posted none appear to really have an answer other than to throw stones. You apparently have found the answer! Could you quote from the books that you are refering to the angle of radiation relative to the radiator, thats it ? If you can't understand that then relay to me the angle of a radiation front relative to a radiator, I'm sure some other people are interested in what you found. Even better, let me know the TOA of a dipole in free space and how much it varies to that of the same dipole over a perfect ground. Use a computor program if you like, anything that sheds light on the matter . The books say that a horizontal "v" antenna should be tipped for max gain, doesn't that raise your interest about the reasoning and mathematics behind this? Jimmie D asked me to state this angle but I have only a expensive computor program that doesn't give the math with the answer. Please read off the angle and the specifics so we all can move on, I don't want a 160 thread postings some thrust upon Walt Art The V antenna is a terminated traveling wave antenna the dipoles that you have been refering to are standingwave antennas. You are comparing apples and oranges. The best I can tell is that all other references you made to tilt have been perpedicular to the direction of the wave front. The V antenna is tilted in the direction of the wave front, more apples and oranges. Throw in some grapes and pineapple and we will have fruit salad. Jimmie |
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