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Cecil Moore wrote:
Tom Donaly wrote: Current waves can travel in two directions at the same time. Charge can't. Quoting Kraus: "A coil can also act as a 180 degree phase shifter ..." Exactly how does a coil act as a 180 degree phase shifter if charge cannot travel in two directions? Seems that you also don't comprehend the nature of a distributed network such as a bugcatcher loading coil. For a guy who doesn't seem to be able to make the distinction, you don't have any business criticizing Tom Rauch's understanding of the situation. So you believe that charge density is constant throughout an RF distributed network? -- 73, Cecil http://www.qsl.net/w5dxp -----= Posted via Newsfeeds.Com, Uncensored Usenet News =----- http://www.newsfeeds.com - The #1 Newsgroup Service in the World! -----== Over 100,000 Newsgroups - 19 Different Servers! =----- A charge defined at one point can go one direction or another, Cecil, as in current, but not two opposing directions at once. And quit telling me what I believe; I'll tell you. Let me say in terms you might get this time: The same infinitesimal charge dQ cannot move in two directions at the same time. In order to do that it would have to split in two and that would violate the principle of conservation of charge. 73, Tom Donaly, KA6RUH |
Richard Clark wrote:
. . . However, Beverages are not typically the first choice for transmission, but rather reception. Does reciprocity hold? As no one has offered to help the Little Red Hen, would they care to share in the cake? For the receive single wire Beverage @ 10° w/600 Ohm load Total load power = 5.543E-07 watts For the receive double wire Beverage @ 10° w/600 Ohm load Total load power = 6.623E-07 watts Now, if we compare the two receive loads we find they differ by .77dB which is the same difference for the transmission models. By most accounts, that means reciprocity prevails. By further accounts, that means the double wire system is superior - if you want to lay out 1000 meters of wire for less than one dB (that pesky one dB value judgment again). . . . You wouldn't modify a Beverage or any HF receiving antenna to get more gain. The whole object is directivity. If you need more gain, turn up the receiver gain control. Of course reciprocity prevails. But at HF, the important criteria are different for transmitting and receiving. When transmitting, it's gain; when receiving, it's directivity. The Beverage is poor in the first category but good in the second -- it's a good receiving antenna but a poor transmitting antenna. Incidentally, Tom W8JI and I worked out a way some time ago to get directivity information from EZNEC. You can see an example at http://www.w8ji.com/receiving_basics.htm in the discussion about Beverages. Roy Lewallen, W7EL |
On Thu, 26 Aug 2004 21:16:14 -0700, Roy Lewallen
wrote: Richard Clark wrote: . . . However, Beverages are not typically the first choice for transmission, but rather reception. Does reciprocity hold? As no one has offered to help the Little Red Hen, would they care to share in the cake? For the receive single wire Beverage @ 10° w/600 Ohm load Total load power = 5.543E-07 watts For the receive double wire Beverage @ 10° w/600 Ohm load Total load power = 6.623E-07 watts Now, if we compare the two receive loads we find they differ by .77dB which is the same difference for the transmission models. By most accounts, that means reciprocity prevails. By further accounts, that means the double wire system is superior - if you want to lay out 1000 meters of wire for less than one dB (that pesky one dB value judgment again). . . . You wouldn't modify a Beverage or any HF receiving antenna to get more gain. The whole object is directivity. If you need more gain, turn up the receiver gain control. If you will note above, there is nothing stated in terms of gain. Of course reciprocity prevails. But at HF, the important criteria are different for transmitting and receiving. When transmitting, it's gain; If you will note in the original posting (the content that has been edited out here) I do employ the term gain - however only as an informal comparison. when receiving, it's directivity. The Beverage is poor in the first category but good in the second -- it's a good receiving antenna but a poor transmitting antenna. That has been attended to several times. Incidentally, Tom W8JI and I worked out a way some time ago to get directivity information from EZNEC. You can see an example at http://www.w8ji.com/receiving_basics.htm in the discussion about Beverages. Hi Roy, That's nice. Do you have anything that resolves Yuri's "problem?" More to the matter, does anyone know what that "problem" is? If it is merely semantics (as the discussion seems to have evolved into), then perhaps this matter is more suitable to rec.radio.amateur.linguistics. 73's Richard Clark, KB7QHC |
Hi Yuri, As this is not demonstrated (significantly) through EZNEC in my models, perhaps you can provide your model that does? 73's Richard Clark, KB7QHC I do not have EZNEC model, but you can read up the thread at http://lists.contesting.com/archives...-08/index.html and look for 2 wire beverages tec. Someone tested single wire Beverage and then laid "return" wire underneath on the ground and noticed deterioration of F/B and higher angle lobes. Yuri |
Richard Clark wrote:
Hi Roy, That's nice. Do you have anything that resolves Yuri's "problem?" More to the matter, does anyone know what that "problem" is? If it is merely semantics (as the discussion seems to have evolved into), then perhaps this matter is more suitable to rec.radio.amateur.linguistics. 73's Richard Clark, KB7QHC I've already said all I have to say about Yuri's problems. Roy Lewallen, W7EL |
Yuri, K3BU wrote:
"I can see conductor (assuming insulated wire) having its electrical length affected by the capacitance between wire and earth, but wouldn`t current stay close to same along the length?" Depends on distance from the source. Current fades fast close to the source, but at a great distance, the decline is very slow. Traveling waves don`t require a complete electrical circuit for propagation. They travel well in a complete void. So, the volts and amps far from the wave source don`t need to equal those at the source. V=frequency times wavelength always prevails. So, capacitance between wire and earth for a given frequency changes the wavelength because the velocity of the wave is changed (slowed) by proximity of the earth. As a traveling wave is free to be attenuated in travel, current must decline enroute. Brown, Lewis, & Epstein, the 20th Century RCA geniuses, declared that the place to end extending ground radials is where their current becomes insignificant. Yuri also wrote: "Why do we use radials if the conductors become lossy?" Yuri also had answered the question before asking. Didn`t Johnny Carson patent that routine, holding the question envelope to his head while he gave the answer? Yuti`s answer: "Wire and dirt, with less resistance wire taking over." Yuri also wrote: "Why does the Beverage laid on the ground work?" Kraus says a wave traveling along a perfect conductor produces an electric field perpendicular to the conducting surface, but along the earth the electric field has a forward tilt. The horizontal component of the vertical wave produced by the tilt is associated with that part of the wave that enters the surface and is dissipated as heat. The vertical component of the wave continues to travel along the surface. The emfs induced along the antenna by the horizontal component made of the tilt, all add up in the same phase at the receiver. Maximum response is in the direction of the horizontal wire. Best regards, Richard Harrison, KB5WZI |
Yuri said he would send me a check for the issues I didn't get and he
was true to his word. The check came in the mail today. Thank you Yuri. 73 Henry WA0GOZ Yuri Blanarovich wrote: Can you describe what is on the label, with codes if any please? Thanks, Yuri Sure WA0GOZ S You are right, I found it on the computer.Printed listings missed it, because I received your check on 89/06/06 after the regular 8905 issue was mailed, your payment arrived later, I sent you 8905 issue and it didn't show up on the printout. Searching computer I found it. I have mailed check with refund today. I am sorry for mixup, comments and above all, that I was not able to continue publishing and sinking money into Radiosporting. I am still hoping to scan old issues and perhaps continue with it on Internet (no money outlay for printing), but only as time permitting. I am glad we could sort thing out. 73 Yuri |
Hi Yuri,
This is like offering an encyclopedia and saying an article about some famous guy is in there. Never mind. The data speaks for itself - less than a dB difference. 73's Richard Clark, KB7QHC Not really, it is more like saying there is a word or discussion about 2 wire beverages on page so and so (last few days). Discussion was quite sizable and worth looking into for those who only play with "soft" antennas and see what experiences were gained by those who played with real antennas. It was midnight here and I was closing the shop for the day in anticipation of getting up early. I had no time to go and do the digest or get into arguments of what IS is. Your data speaks of less than one dB, reality is bit different. But I know, its me (problem), not the software. Maybe a little less sarcasm would go longer way? 73 Yuri |
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