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#1
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In article , NM5K wrote:
Yep.. I think the frustration tends to be difficulty in understanding that it's just one type of system, and others that do not require any ground connection do exist. Which means you would have to classify his statement as incorrect in the overall larger picture. I believe most have already stated that while some antennas do require such a connection, any "complete" antenna does not require one. Correct. One interesting counter-example, would be the simple one of a full-wavelength loop of wire, which is fed with a balanced feedline (twinlead or open-wire or ladder line), which is fed from a fully-balanced transmitter output stage (e.g. with transformer coupling from the driver transistors). To be extreme about it, let's say that the transmitter is itself based on a fully-balanced (differential) circuit, all the way back to the crystal oscillator. It's powered by a single battery, and is installed in a plastic chassic. This sort of antenna would have no galvanic connection to "earth" at all. Measure the resistance or RF impedance between any part of the antenna or feedline structure, and *anything* not part of the antenna, and the result will be "huge". Since it's a loop antenna, it has no "ends"... no points at which electrons could "fly off". The net current flow going up the feedline to the antenna will be zero, at all points - a positive current on one side of the feedline will be exactly balanced by a negative current on the other side of the feedline. There are no "excess" electrons or charge flowing in either direction. You can even insulate the antenna wires, if you wish. It will transmit just fine, with no connection at all to "ground". Disconnect the transmitter, install a receiver of a similar "balanced and isolated" design, and it'll receive just as well... again, with no connection to "ground". -- Dave Platt AE6EO Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior I do _not_ wish to receive unsolicited commercial email, and I will boycott any company which has the gall to send me such ads! |
#2
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![]() "Dave Platt" napisa³ w wiadomo¶ci ... Since it's a loop antenna, it has no "ends"... no points at which electrons could "fly off". A loop antena have the antinodes. The points at which electrons could "fly off". See Fig. 2: http://www.antiquewireless.org/otb/lodge1102.htm The net current flow going up the feedline to the antenna will be zero, at all points - a positive current on one side of the feedline will be exactly balanced by a negative current on the other side of the feedline. There are no "excess" electrons or charge flowing in either direction. ""A further feature of the structure of negative coronas is that as the electrons drift outwards, they encounter neutral molecules and, withelectronegative molecules (such as oxygen and water vapor), combine to produce negative ions. These negative ions are then attracted to the positive uncurved electrode, completing the 'circuit'.". From: Negative coronas. Mechanism. http://en.wikipedia.org/wiki/Corona_...gative_coronas In the each antenna is the excess/deficit of electrons and "charge flowing in either direction." But the negative corona and the positive corona are not simmetrical. At transmitting you have the deficit and at receiving the excess. Without the earth the static build up and radio stop working. You can even insulate the antenna wires, if you wish. Can you measure the static electricity? It will transmit just fine, with no connection at all to "ground". Disconnect the transmitter, install a receiver of a similar "balanced and isolated" design, and it'll receive just as well... again, with no connection to "ground". You will transmit just fine if you have the ground/chassis/counterpoise. S* |
#3
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Szczepan Bialek wrote:
At transmitting you have the deficit and at receiving the excess. Without the earth the static build up and radio stop working. How would you know that when you don't even have a transmitter? You will transmit just fine if you have the ground/chassis/counterpoise. S* And without it, fine as well. |
#4
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![]() "Rob" napisal w wiadomosci ... Szczepan Bialek wrote: At transmitting you have the deficit and at receiving the excess. Without the earth the static build up and radio stop working. How would you know that when you don't even have a transmitter? But my "friend" Marconi had a lot. He wrote: "but in my opinion no practical system of wireless telegraphy exists where the instruments are not connected to earth." You will transmit just fine if you have the ground/chassis/counterpoise. S* And without it, fine as well. It is not true. You know that. S* |
#5
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![]() "Szczepan Bialek" wrote in message ... "Rob" napisal w wiadomosci ... Szczepan Bialek wrote: At transmitting you have the deficit and at receiving the excess. Without the earth the static build up and radio stop working. How would you know that when you don't even have a transmitter? But my "friend" Marconi had a lot. He wrote: "but in my opinion no practical system of wireless telegraphy exists where the instruments are not connected to earth." You will transmit just fine if you have the ground/chassis/counterpoise. S* And without it, fine as well. It is not true. You know that. S* Hello chaps. Several of you have said that Szczepan seems unable to accept new ideas. I see that he persists in believing Marconi's comment that an earth connection is necessary. Those of us who use Yagi , loop or dipole aerials know, through experience, that an earth connection is not necessary. I am undecided why he prefers to believe the opinion of someone who worked in the early days of radio rather than those of us who use radio in modern times. I feel it is awkward to say that Marconi was wrong even though we now know this is the case. Personally, I'd say that Marconi's opinion that "no practical system of wireless telegraphy exists where the instruments are not connected to earth" obviously related to his own use of wireless. As I understand it, Marconi's aerials were not resonant at the frequency he was using. They would therefore be a mis-match to his radios and this situation was alleviated by using connections to earth. I find it puzzling that Szczepan feels happy to ignore our comments and continue to accept Marconi's opinion given that he (Szczepan) said that a transmitter is a "black box" to him. I've speculated that his English may not be very good but I shall be amused if we find out that his first language is English despite his non-English name. He never answered my question about resonant / non-resonant aerials so I guess his technical knowledge is limited. Kindest regards to all, Ian. ps: If Szczepan is happy to constrain his knowledge to the days of Marconi then I wonder how come he is using a computer. Didn't have those in the days of Marconi. |
#6
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Ian wrote:
I feel it is awkward to say that Marconi was wrong even though we now know this is the case. Personally, I'd say that Marconi's opinion that "no practical system of wireless telegraphy exists where the instruments are not connected to earth" obviously related to his own use of wireless. As I understand it, Marconi's aerials were not resonant at the frequency he was using. They would therefore be a mis-match to his radios and this situation was alleviated by using connections to earth. Little of the technology in use today was known in Marconi's time. Marconi knew nothing of resonance, impedance, or electromagnetic field theory; it all came after his time. Marconi would have been totally baffled if shown a helical, slot, yagi, or any number of antennas invented after his time in common use today. The only reference antenna Marconi had was a wire of some sort fed against ground. For that particular type of antenna, Marconi was correct, but his statement is NOT correct for antennas in general. |
#7
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wrote in message
... Ian wrote: Little of the technology in use today was known in Marconi's time. Marconi knew nothing of resonance, impedance, or electromagnetic field theory; it all came after his time. Marconi would have been totally baffled if shown a helical, slot, yagi, or any number of antennas invented after his time in common use today. The only reference antenna Marconi had was a wire of some sort fed against ground. For that particular type of antenna, Marconi was correct, but his statement is NOT correct for antennas in general. Hello again. I bet that Marconi would have been very wiling to learn about new theory and technology ... unlike some people. Regards, Ian. |
#8
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Szczepan Bialek wrote:
It is not true. You know that. Marconi was wrong. Most of the antennas in use today were not invented until after Marconi. Marconi would be totally baffled if he were shown a helical, yagi or slot antenna. |
#9
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On 4/17/2012 10:47 AM, Szczepan Bialek wrote:
napisal w wiadomosci ... Szczepan wrote: At transmitting you have the deficit and at receiving the excess. Without the earth the static build up and radio stop working. How would you know that when you don't even have a transmitter? But my "friend" Marconi had a lot. He wrote: "but in my opinion no practical system of wireless telegraphy exists where the instruments are not connected to earth." You will transmit just fine if you have the ground/chassis/counterpoise. S* And without it, fine as well. It is not true. You know that. S* I guess all the people I talk to using that portable rig are just a figment of my imagination? And likewise here at the house where most of my systems are ungrounded.. It's actually quite astounding.. I've worked about 29 zillion people using various ungrounded antenna systems that don't work. How did I pull off such a feat? Did I scream real loud? Did I hire R. Lee Ermey to scream for me? He's pretty good at it.. Maybe I built a big fire behind the radio, and sent smoke signals.. I suppose that could be a viable explanation, being as that land was Indian Territory until a couple of years before Marconi made that statement. :\ I don't own any war drums, so we would have to rule those out.. :| Maybe I pass notes around the country on the backs of tarantulas.. They usually don't mind as long as I don't use a hat pin to attach the notes to their backs. http://home.comcast.net/~disk100/oct17-4.jpg |
#10
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![]() "NM5K" wrote in message ... On 4/17/2012 10:47 AM, Szczepan Bialek wrote: napisal w wiadomosci ... Szczepan wrote: At transmitting you have the deficit and at receiving the excess. Without the earth the static build up and radio stop working. How would you know that when you don't even have a transmitter? But my "friend" Marconi had a lot. He wrote: "but in my opinion no practical system of wireless telegraphy exists where the instruments are not connected to earth." You will transmit just fine if you have the ground/chassis/counterpoise. S* And without it, fine as well. It is not true. You know that. S* # I guess all the people I talk to using that portable rig # are just a figment of my imagination? snip Nope. Not at all. I have quite a few contacts with a Heathkit HW-7 powered with 8 "D" cells, a homebrew balanced tuner and open wire dipole. This was use on board a sailboat. |
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