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On 1/6/2014 11:04 PM, Jeff Liebermann wrote:
On Tue, 7 Jan 2014 03:19:54 +0000 (UTC), gregz wrote: Jerry Stuckle wrote: On 1/6/2014 1:28 AM, gregz wrote: wrote: "only 3 db", but that's twice the signal. I have mine stacked 12 feet, but I believe Winegard says either 8 or 10 feet. Mine work swell. +:^] I got mine just after they were discontinued in 2005/6. Had to email a number of suppliers until I found the second one. I bet there are some still in storage somewhere, email different places that sell Winegard, you may still find one. John K9RZZ Twice the signal means twice the voltage, for me. Greg Twice the voltage is a 6 db gain. Twice the power is a 3db gain. Exactly. If I got 1 microvolt, 2 microvolts will be twice the signal. Greg Sorta. If you got 1 microvolt, 2 microvolts will be twice the signal voltage but only 1.414 times the signal power. That's why we have units of measure to avoid such ambiguities. Just to be difficult, working with antennas, the "signal" is the field strength measured in dBuV/M. If you define what you're measuring and specify your units of measure, you wouldn't be having such problems. You've got it backwards, Jeff. Twice the voltage is 4 times the power. 1.414 times the voltage would be twice the power. -- ================== Remove the "x" from my email address Jerry, AI0K ================== |
#2
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On Mon, 06 Jan 2014 23:23:56 -0500, Jerry Stuckle
wrote: On 1/6/2014 11:04 PM, Jeff Liebermann wrote: On Tue, 7 Jan 2014 03:19:54 +0000 (UTC), gregz wrote: Jerry Stuckle wrote: On 1/6/2014 1:28 AM, gregz wrote: wrote: "only 3 db", but that's twice the signal. I have mine stacked 12 feet, but I believe Winegard says either 8 or 10 feet. Mine work swell. +:^] I got mine just after they were discontinued in 2005/6. Had to email a number of suppliers until I found the second one. I bet there are some still in storage somewhere, email different places that sell Winegard, you may still find one. John K9RZZ Twice the signal means twice the voltage, for me. Greg Twice the voltage is a 6 db gain. Twice the power is a 3db gain. Exactly. If I got 1 microvolt, 2 microvolts will be twice the signal. Greg Sorta. If you got 1 microvolt, 2 microvolts will be twice the signal voltage but only 1.414 times the signal power. That's why we have units of measure to avoid such ambiguities. Just to be difficult, working with antennas, the "signal" is the field strength measured in dBuV/M. If you define what you're measuring and specify your units of measure, you wouldn't be having such problems. You've got it backwards, Jeff. Twice the voltage is 4 times the power. 1.414 times the voltage would be twice the power. Very embarrassing. Temporary loss of IQ from working on my broken car with a cold or flu this afternoon. It should be: If you got 1 microvolt, 2 microvolts will be twice the signal voltage but 4 times the signal power. Thanks for the correction (grumble)... Maybe if I go to sleep early, when I wake up tomorrow, this didn't happen. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#3
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Jeff Liebermann wrote:
On Mon, 06 Jan 2014 23:23:56 -0500, Jerry Stuckle wrote: On 1/6/2014 11:04 PM, Jeff Liebermann wrote: On Tue, 7 Jan 2014 03:19:54 +0000 (UTC), gregz wrote: Jerry Stuckle wrote: On 1/6/2014 1:28 AM, gregz wrote: wrote: "only 3 db", but that's twice the signal. I have mine stacked 12 feet, but I believe Winegard says either 8 or 10 feet. Mine work swell. +:^] I got mine just after they were discontinued in 2005/6. Had to email a number of suppliers until I found the second one. I bet there are some still in storage somewhere, email different places that sell Winegard, you may still find one. John K9RZZ Twice the signal means twice the voltage, for me. Greg Twice the voltage is a 6 db gain. Twice the power is a 3db gain. Exactly. If I got 1 microvolt, 2 microvolts will be twice the signal. Greg Sorta. If you got 1 microvolt, 2 microvolts will be twice the signal voltage but only 1.414 times the signal power. That's why we have units of measure to avoid such ambiguities. Just to be difficult, working with antennas, the "signal" is the field strength measured in dBuV/M. If you define what you're measuring and specify your units of measure, you wouldn't be having such problems. You've got it backwards, Jeff. Twice the voltage is 4 times the power. 1.414 times the voltage would be twice the power. Very embarrassing. Temporary loss of IQ from working on my broken car with a cold or flu this afternoon. It should be: If you got 1 microvolt, 2 microvolts will be twice the signal voltage but 4 times the signal power. Thanks for the correction (grumble)... Maybe if I go to sleep early, when I wake up tomorrow, this didn't happen. I have not really been specifying units. I was just going over the situation in my mind, and I straightened out in rf terms. I got this going out terminology. IF, in audio, I got two speakers transmitting equal energy, with two amps or channels, and I receive that totally in phase, I got twice the signal or 6 dB power increase. I've measured it. It's true. Same thing would happen with two antennas with two transmitters. Two antennas, one transmitter, with one splitter would only give 3 dB power increase at the receiver. I'm just thinking out loud. I had to ease my mind. I think I'm ok now. Almost bedtime. Greg |
#4
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gregz wrote:
Jeff Liebermann wrote: On Mon, 06 Jan 2014 23:23:56 -0500, Jerry Stuckle wrote: On 1/6/2014 11:04 PM, Jeff Liebermann wrote: On Tue, 7 Jan 2014 03:19:54 +0000 (UTC), gregz wrote: Jerry Stuckle wrote: On 1/6/2014 1:28 AM, gregz wrote: wrote: "only 3 db", but that's twice the signal. I have mine stacked 12 feet, but I believe Winegard says either 8 or 10 feet. Mine work swell. +:^] I got mine just after they were discontinued in 2005/6. Had to email a number of suppliers until I found the second one. I bet there are some still in storage somewhere, email different places that sell Winegard, you may still find one. John K9RZZ Twice the signal means twice the voltage, for me. Greg Twice the voltage is a 6 db gain. Twice the power is a 3db gain. Exactly. If I got 1 microvolt, 2 microvolts will be twice the signal. Greg Sorta. If you got 1 microvolt, 2 microvolts will be twice the signal voltage but only 1.414 times the signal power. That's why we have units of measure to avoid such ambiguities. Just to be difficult, working with antennas, the "signal" is the field strength measured in dBuV/M. If you define what you're measuring and specify your units of measure, you wouldn't be having such problems. You've got it backwards, Jeff. Twice the voltage is 4 times the power. 1.414 times the voltage would be twice the power. Very embarrassing. Temporary loss of IQ from working on my broken car with a cold or flu this afternoon. It should be: If you got 1 microvolt, 2 microvolts will be twice the signal voltage but 4 times the signal power. Thanks for the correction (grumble)... Maybe if I go to sleep early, when I wake up tomorrow, this didn't happen. I have not really been specifying units. I was just going over the situation in my mind, and I straightened out in rf terms. I got this going out terminology. IF, in audio, I got two speakers transmitting equal energy, with two amps or channels, and I receive that totally in phase, I got twice the signal or 6 dB power increase. I've measured it. It's true. Same thing would happen with two antennas with two transmitters. Two antennas, one transmitter, with one splitter would only give 3 dB power increase at the receiver. I'm just thinking out loud. I had to ease my mind. I think I'm ok now. Almost bedtime. Greg Tomorrow I will think the reverse of the antenna reception combining. It does not work for me right now. Greg |
#5
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On 1/7/2014 2:29 AM, gregz wrote:
Jeff Liebermann wrote: On Mon, 06 Jan 2014 23:23:56 -0500, Jerry Stuckle wrote: On 1/6/2014 11:04 PM, Jeff Liebermann wrote: On Tue, 7 Jan 2014 03:19:54 +0000 (UTC), gregz wrote: Jerry Stuckle wrote: On 1/6/2014 1:28 AM, gregz wrote: wrote: "only 3 db", but that's twice the signal. I have mine stacked 12 feet, but I believe Winegard says either 8 or 10 feet. Mine work swell. +:^] I got mine just after they were discontinued in 2005/6. Had to email a number of suppliers until I found the second one. I bet there are some still in storage somewhere, email different places that sell Winegard, you may still find one. John K9RZZ Twice the signal means twice the voltage, for me. Greg Twice the voltage is a 6 db gain. Twice the power is a 3db gain. Exactly. If I got 1 microvolt, 2 microvolts will be twice the signal. Greg Sorta. If you got 1 microvolt, 2 microvolts will be twice the signal voltage but only 1.414 times the signal power. That's why we have units of measure to avoid such ambiguities. Just to be difficult, working with antennas, the "signal" is the field strength measured in dBuV/M. If you define what you're measuring and specify your units of measure, you wouldn't be having such problems. You've got it backwards, Jeff. Twice the voltage is 4 times the power. 1.414 times the voltage would be twice the power. Very embarrassing. Temporary loss of IQ from working on my broken car with a cold or flu this afternoon. It should be: If you got 1 microvolt, 2 microvolts will be twice the signal voltage but 4 times the signal power. Thanks for the correction (grumble)... Maybe if I go to sleep early, when I wake up tomorrow, this didn't happen. I have not really been specifying units. I was just going over the situation in my mind, and I straightened out in rf terms. I got this going out terminology. IF, in audio, I got two speakers transmitting equal energy, with two amps or channels, and I receive that totally in phase, I got twice the signal or 6 dB power increase. I've measured it. It's true. Same thing would happen with two antennas with two transmitters. Two antennas, one transmitter, with one splitter would only give 3 dB power increase at the receiver. I'm just thinking out loud. I had to ease my mind. I think I'm ok now. Almost bedtime. Greg No, two in-phase speakers provide 3db increase, not 6db. If you could double the signal and get 4x the power you could make gazillions! Of course, you'd be creating energy out of nothing, but who cares about the laws of physics? ![]() -- ================== Remove the "x" from my email address Jerry, AI0K ================== |
#6
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In message , Jerry Stuckle
writes On 1/7/2014 2:29 AM, gregz wrote: Jeff Liebermann wrote: On Mon, 06 Jan 2014 23:23:56 -0500, Jerry Stuckle wrote: On 1/6/2014 11:04 PM, Jeff Liebermann wrote: On Tue, 7 Jan 2014 03:19:54 +0000 (UTC), gregz wrote: Jerry Stuckle wrote: On 1/6/2014 1:28 AM, gregz wrote: wrote: "only 3 db", but that's twice the signal. I have mine stacked 12 feet, but I believe Winegard says either 8 or 10 feet. Mine work swell. +:^] I got mine just after they were discontinued in 2005/6. Had to email a number of suppliers until I found the second one. I bet there are some still in storage somewhere, email different places that sell Winegard, you may still find one. John K9RZZ Twice the signal means twice the voltage, for me. Greg Twice the voltage is a 6 db gain. Twice the power is a 3db gain. Exactly. If I got 1 microvolt, 2 microvolts will be twice the signal. Greg Sorta. If you got 1 microvolt, 2 microvolts will be twice the signal voltage but only 1.414 times the signal power. That's why we have units of measure to avoid such ambiguities. Just to be difficult, working with antennas, the "signal" is the field strength measured in dBuV/M. If you define what you're measuring and specify your units of measure, you wouldn't be having such problems. You've got it backwards, Jeff. Twice the voltage is 4 times the power. 1.414 times the voltage would be twice the power. Very embarrassing. Temporary loss of IQ from working on my broken car with a cold or flu this afternoon. It should be: If you got 1 microvolt, 2 microvolts will be twice the signal voltage but 4 times the signal power. Thanks for the correction (grumble)... Maybe if I go to sleep early, when I wake up tomorrow, this didn't happen. I have not really been specifying units. I was just going over the situation in my mind, and I straightened out in rf terms. I got this going out terminology. IF, in audio, I got two speakers transmitting equal energy, with two amps or channels, and I receive that totally in phase, I got twice the signal or 6 dB power increase. I've measured it. It's true. Same thing would happen with two antennas with two transmitters. Two antennas, one transmitter, with one splitter would only give 3 dB power increase at the receiver. I'm just thinking out loud. I had to ease my mind. I think I'm ok now. Almost bedtime. Greg No, two in-phase speakers provide 3db increase, not 6db. If you could double the signal and get 4x the power you could make gazillions! Of course, you'd be creating energy out of nothing, but who cares about the laws of physics? ![]() Two identical receiving antennas would provide twice the signal voltage if their RF outputs were connected in series. One way of doing this would be for coax feed from each antenna to be connected to the primary of a 1:1 RF transformer, and the secondaries of the two transformers were connected in series. So if each antenna delivered 1V from a resistive source impedance (R) of 1 ohm into a matched resistive load of 1 ohm, the two secondaries in series would provide 2V. However, the output impedance of the two secondaries would be twice that of each antenna, ie 2R. To preserve matching, the load would also have to be 2R. However, the snag is..... The matched power from each antenna is 1V squared divided by 1 ohm (=1W), but the matched power from the combined antennas is 2V squared divided by 2 ohms (=2W) - which is an increase of 3dB (and not 6dB). Of course, if the receiver input was not matched, and its impedance was much higher than R or 2R, it might be possible to benefit from adding the two antenna signals in this way. Has anybody tried this? -- Ian |
#7
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![]() No, two in-phase speakers provide 3db increase, not 6db. If you could double the signal and get 4x the power you could make gazillions! Of course, you'd be creating energy out of nothing, but who cares about the laws of physics? ![]() Two identical receiving antennas would provide twice the signal voltage if their RF outputs were connected in series. One way of doing this would be for coax feed from each antenna to be connected to the primary of a 1:1 RF transformer, and the secondaries of the two transformers were connected in series. So if each antenna delivered 1V from a resistive source impedance (R) of 1 ohm into a matched resistive load of 1 ohm, the two secondaries in series would provide 2V. However, the output impedance of the two secondaries would be twice that of each antenna, ie 2R. To preserve matching, the load would also have to be 2R. However, the snag is..... The matched power from each antenna is 1V squared divided by 1 ohm (=1W), but the matched power from the combined antennas is 2V squared divided by 2 ohms (=2W) - which is an increase of 3dB (and not 6dB). Of course, if the receiver input was not matched, and its impedance was much higher than R or 2R, it might be possible to benefit from adding the two antenna signals in this way. Has anybody tried this? I don't think anyone would try this because every television input is either 75 or 300 ohms or both. Hoping for an input of 1000 ohms would be a vain hope. |
#8
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In message , boomer
writes No, two in-phase speakers provide 3db increase, not 6db. If you could double the signal and get 4x the power you could make gazillions! Of course, you'd be creating energy out of nothing, but who cares about the laws of physics? ![]() Two identical receiving antennas would provide twice the signal voltage if their RF outputs were connected in series. One way of doing this would be for coax feed from each antenna to be connected to the primary of a 1:1 RF transformer, and the secondaries of the two transformers were connected in series. So if each antenna delivered 1V from a resistive source impedance (R) of 1 ohm into a matched resistive load of 1 ohm, the two secondaries in series would provide 2V. However, the output impedance of the two secondaries would be twice that of each antenna, ie 2R. To preserve matching, the load would also have to be 2R. However, the snag is..... The matched power from each antenna is 1V squared divided by 1 ohm (=1W), but the matched power from the combined antennas is 2V squared divided by 2 ohms (=2W) - which is an increase of 3dB (and not 6dB). Of course, if the receiver input was not matched, and its impedance was much higher than R or 2R, it might be possible to benefit from adding the two antenna signals in this way. Has anybody tried this? I don't think anyone would try this because every television input is either 75 or 300 ohms or both. I think you might be surprised at how unlike the supposed 75 or 300 ohms some TV sets might be. Hoping for an input of 1000 ohms would be a vain hope. Possibly a purpose-built preamp could be designed to have a distinctly higher input impedance. Of course, it would also have to have an appropriately low noise figure (certainly at least as good as the receiver). -- Ian |
#9
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On 1/7/2014 9:06 AM, Ian Jackson wrote:
In message , Jerry Stuckle writes On 1/7/2014 2:29 AM, gregz wrote: Jeff Liebermann wrote: On Mon, 06 Jan 2014 23:23:56 -0500, Jerry Stuckle wrote: On 1/6/2014 11:04 PM, Jeff Liebermann wrote: On Tue, 7 Jan 2014 03:19:54 +0000 (UTC), gregz wrote: Jerry Stuckle wrote: On 1/6/2014 1:28 AM, gregz wrote: wrote: "only 3 db", but that's twice the signal. I have mine stacked 12 feet, but I believe Winegard says either 8 or 10 feet. Mine work swell. +:^] I got mine just after they were discontinued in 2005/6. Had to email a number of suppliers until I found the second one. I bet there are some still in storage somewhere, email different places that sell Winegard, you may still find one. John K9RZZ Twice the signal means twice the voltage, for me. Greg Twice the voltage is a 6 db gain. Twice the power is a 3db gain. Exactly. If I got 1 microvolt, 2 microvolts will be twice the signal. Greg Sorta. If you got 1 microvolt, 2 microvolts will be twice the signal voltage but only 1.414 times the signal power. That's why we have units of measure to avoid such ambiguities. Just to be difficult, working with antennas, the "signal" is the field strength measured in dBuV/M. If you define what you're measuring and specify your units of measure, you wouldn't be having such problems. You've got it backwards, Jeff. Twice the voltage is 4 times the power. 1.414 times the voltage would be twice the power. Very embarrassing. Temporary loss of IQ from working on my broken car with a cold or flu this afternoon. It should be: If you got 1 microvolt, 2 microvolts will be twice the signal voltage but 4 times the signal power. Thanks for the correction (grumble)... Maybe if I go to sleep early, when I wake up tomorrow, this didn't happen. I have not really been specifying units. I was just going over the situation in my mind, and I straightened out in rf terms. I got this going out terminology. IF, in audio, I got two speakers transmitting equal energy, with two amps or channels, and I receive that totally in phase, I got twice the signal or 6 dB power increase. I've measured it. It's true. Same thing would happen with two antennas with two transmitters. Two antennas, one transmitter, with one splitter would only give 3 dB power increase at the receiver. I'm just thinking out loud. I had to ease my mind. I think I'm ok now. Almost bedtime. Greg No, two in-phase speakers provide 3db increase, not 6db. If you could double the signal and get 4x the power you could make gazillions! Of course, you'd be creating energy out of nothing, but who cares about the laws of physics? ![]() Two identical receiving antennas would provide twice the signal voltage if their RF outputs were connected in series. One way of doing this would be for coax feed from each antenna to be connected to the primary of a 1:1 RF transformer, and the secondaries of the two transformers were connected in series. So if each antenna delivered 1V from a resistive source impedance (R) of 1 ohm into a matched resistive load of 1 ohm, the two secondaries in series would provide 2V. However, the output impedance of the two secondaries would be twice that of each antenna, ie 2R. To preserve matching, the load would also have to be 2R. However, the snag is..... The matched power from each antenna is 1V squared divided by 1 ohm (=1W), but the matched power from the combined antennas is 2V squared divided by 2 ohms (=2W) - which is an increase of 3dB (and not 6dB). Of course, if the receiver input was not matched, and its impedance was much higher than R or 2R, it might be possible to benefit from adding the two antenna signals in this way. Has anybody tried this? But then I DID qualify my statement with "if the resistance (impedance in this case) stays the same". In your case, as you indicated, it is not the same. For the same impedance you would need a matching network. Assuming no loss in the matching network, the output would be 1.414V. -- ================== Remove the "x" from my email address Jerry Stuckle JDS Computer Training Corp. ================== |
#10
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Jerry Stuckle wrote:
On 1/7/2014 2:29 AM, gregz wrote: Jeff Liebermann wrote: On Mon, 06 Jan 2014 23:23:56 -0500, Jerry Stuckle wrote: On 1/6/2014 11:04 PM, Jeff Liebermann wrote: On Tue, 7 Jan 2014 03:19:54 +0000 (UTC), gregz wrote: Jerry Stuckle wrote: On 1/6/2014 1:28 AM, gregz wrote: wrote: "only 3 db", but that's twice the signal. I have mine stacked 12 feet, but I believe Winegard says either 8 or 10 feet. Mine work swell. +:^] I got mine just after they were discontinued in 2005/6. Had to email a number of suppliers until I found the second one. I bet there are some still in storage somewhere, email different places that sell Winegard, you may still find one. John K9RZZ Twice the signal means twice the voltage, for me. Greg Twice the voltage is a 6 db gain. Twice the power is a 3db gain. Exactly. If I got 1 microvolt, 2 microvolts will be twice the signal. Greg Sorta. If you got 1 microvolt, 2 microvolts will be twice the signal voltage but only 1.414 times the signal power. That's why we have units of measure to avoid such ambiguities. Just to be difficult, working with antennas, the "signal" is the field strength measured in dBuV/M. If you define what you're measuring and specify your units of measure, you wouldn't be having such problems. You've got it backwards, Jeff. Twice the voltage is 4 times the power. 1.414 times the voltage would be twice the power. Very embarrassing. Temporary loss of IQ from working on my broken car with a cold or flu this afternoon. It should be: If you got 1 microvolt, 2 microvolts will be twice the signal voltage but 4 times the signal power. Thanks for the correction (grumble)... Maybe if I go to sleep early, when I wake up tomorrow, this didn't happen. I have not really been specifying units. I was just going over the situation in my mind, and I straightened out in rf terms. I got this going out terminology. IF, in audio, I got two speakers transmitting equal energy, with two amps or channels, and I receive that totally in phase, I got twice the signal or 6 dB power increase. I've measured it. It's true. Same thing would happen with two antennas with two transmitters. Two antennas, one transmitter, with one splitter would only give 3 dB power increase at the receiver. I'm just thinking out loud. I had to ease my mind. I think I'm ok now. Almost bedtime. Greg No, two in-phase speakers provide 3db increase, not 6db. If you could double the signal and get 4x the power you could make gazillions! Of course, you'd be creating energy out of nothing, but who cares about the laws of physics? ![]() The reason big speaker systems work in large places is efficiency gain using multiple arrays, must be in phase. As I was saying, it's a known fact, which I have measured. You can actually get near 10 dB gain using several speakers. It's why horn loudspeakers have gain, better impedance matching to air. I once believed two in phase speakers provided 3 dB increase also. I then read a speaker project by the now famous diAppolito configuration designer in Speaker Builder magazine 80's ?. I can try to find a reference. Greg |
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