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#1
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Try this ...
http://farside.ph.utexas.edu/teachin...es/node94.html This is one of a series of lectures by a prof at Texas Uni. In fact, if you go right back to the home page of http://farside.ph.utexas.edu/teaching, this leads to a most excellent revision of the necessary EM theories, and, briefly glancing thereto, the post grad stuff even exceeds my current interest and knowledge. I'm fairly sure now that this area is where I came across the governing formula that I alluded to recently in this NG when doing my own revision previously in 2005, although the URLs and lecture node numbers have changed since then. |
#2
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On 10/22/2014 5:13 AM, gareth wrote:
Try this ... http://farside.ph.utexas.edu/teachin...es/node94.html This is one of a series of lectures by a prof at Texas Uni. In fact, if you go right back to the home page of http://farside.ph.utexas.edu/teaching, this leads to a most excellent revision of the necessary EM theories, and, briefly glancing thereto, the post grad stuff even exceeds my current interest and knowledge. I'm fairly sure now that this area is where I came across the governing formula that I alluded to recently in this NG when doing my own revision previously in 2005, although the URLs and lecture node numbers have changed since then. Obviously, none of this is new. It states in the article that the short antenna is inefficient due to the wire (ohmic) resistance swamping the radiation resistance. Your first post on this subject did not include wire resistance in your statement that short antennas are inefficient, which is why people jumped on that statement. If you include wire resistance, yes, a short dipole is less efficient that a full-sized dipole (if you can manage to get the power into it, which is a different problem). Note that a short antenna, properly constructed with, say, 4-inch copper pipe will be just about as efficient as one with #12 copper wire. Try it, please. Make the measurements. Record what you get and let us know. We are hungry for additional knowledge. |
#3
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![]() "gareth" wrote in message ... Try this ... http://farside.ph.utexas.edu/teachin...es/node94.html This is one of a series of lectures by a prof at Texas Uni. In fact, if you go right back to the home page of http://farside.ph.utexas.edu/teaching, this leads to a most excellent revision of the necessary EM theories, and, briefly glancing thereto, the post grad stuff even exceeds my current interest and knowledge. I'm fairly sure now that this area is where I came across the governing formula that I alluded to recently in this NG when doing my own revision previously in 2005, although the URLs and lecture node numbers have changed since then. When I get time, I'll browse through the links. However, back to your original assertion that your theory has short antennas as being inefficient compared with longer antennas (I'm assuming you are talking half wave dipoles and such). If 10 watts is delivered to a short antenna, where does it go if it is not radiated just as well as 10 watts delivered to a long antenna? |
#4
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"Wayne" wrote in message
... If 10 watts is delivered to a short antenna, where does it go if it is not radiated just as well as 10 watts delivered to a long antenna? How are you going to deliver that 10 watts? By feeding with 100 Watts? |
#5
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On 10/22/2014 10:05 AM, gareth wrote:
"Wayne" wrote in message ... If 10 watts is delivered to a short antenna, where does it go if it is not radiated just as well as 10 watts delivered to a long antenna? How are you going to deliver that 10 watts? By feeding with 100 Watts? Oops! Is that part of the problem? You never said matching was involved. Please get your story straight. Tell us your requirements. Using real wire? What diameter? What material? What length? Is feeding the antenna part of the problem? What the hell are you seeking? |
#6
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On 10/22/2014 11:15 AM, John S wrote:
What the hell are you seeking? Drama -- Rick |
#7
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"gareth" wrote in message
... I despair that those who are motivated to shout out childish remarks continue to do so, even in the face of an informative post. |
#8
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In message , rickman
writes On 10/22/2014 11:15 AM, John S wrote: What the hell are you seeking? Drama And, of course, confrontation. -- Ian |
#9
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"Ian Jackson" wrote in message
... In message , rickman writes On 10/22/2014 11:15 AM, John S wrote: What the hell are you seeking? Drama And, of course, confrontation. Untrue. The confrontation is sought only by those who seek to respond in a tendentious and abusive manner, such as John S and rickman above. |
#10
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"Wayne" wrote in message
... "gareth" wrote in message ... Try this ... http://farside.ph.utexas.edu/teachin...es/node94.html This is one of a series of lectures by a prof at Texas Uni. In fact, if you go right back to the home page of http://farside.ph.utexas.edu/teaching, this leads to a most excellent revision of the necessary EM theories, and, briefly glancing thereto, the post grad stuff even exceeds my current interest and knowledge. I'm fairly sure now that this area is where I came across the governing formula that I alluded to recently in this NG when doing my own revision previously in 2005, although the URLs and lecture node numbers have changed since then. When I get time, I'll browse through the links. However, back to your original assertion that your theory has short antennas as being inefficient compared with longer antennas (I'm assuming you are talking half wave dipoles and such). If 10 watts is delivered to a short antenna, where does it go if it is not radiated just as well as 10 watts delivered to a long antenna? Dissipated as heat? -- ;-) .. 73 de Frank Turner-Smith G3VKI - mine's a pint. .. http://turner-smith.co.uk |
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