| Page 2 of 2 | 1 | 2 |
|
|
Flex dryer vent hose loop antenna
On Tue, 10 Nov 2015 09:10:00 -0600, amdx wrote:
My magloop nightmare come true: http://www.mixw.co.uk/MagLoop/magloopF.htm I don't get your point here. 1. It's not a fractal. 2. It's more like art than science. 3. It's a variation on my dryer vent hose antenna (tune by pounding). 4. It maximizes most of the worst characteristics of a loop, such as high length to surface area = low Q, small capture area, and optimized for low VSWR. 5. If you're worried about temperature drift, the lack of rigidity should make it drift even more. Build one, monitor your dreams. My ego is too inflated to fit into the loop. I'll stick with the traditional colander on the head arrangement: https://www.google.com/search?q=colander+on+head&tbm=isch Jeff, I don't like the parallel sections, seems like it could be made more complicated using x, y, and z right angles. Nap on that! :-) Mikek Sorry, but everything I've built that involves a 4th dimension has dissapeared when I applied power. The fields cancel and the entire antenna is sucked into the resultant vortex. Argh... I'm late again. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
Flex dryer vent hose loop antenna
On 11/10/2015 9:30 AM, rickman wrote:
On 11/10/2015 9:12 AM, amdx wrote: On 11/10/2015 1:41 AM, rickman wrote: On 11/9/2015 12:08 PM, amdx wrote: The silver is simply optimization. If you can make your coil wire 5% bigger, you should have already done that. Then if you want to optimized 1 + 0.05, silver plate it. Why can't you make the wire 5% bigger again? Where exactly is the cost? You can. I don't think ultimate optimizing is for you. Just make your coil with as much surface area as room will allow. Then know it could have just a tiny bit less loss if you had the silver. That tiny bit of loss will not be noticed in use, except for that little nagging thought... I once had a 6 or 7 turn loop made with 1/4" copper tubing*, Q was about 800 at 1MHz. I could have made it with 1/2" tubing, probably would have had higher Q. I guess the limits are money and how you want to limit physical size and maximum inductance you can use. Did I miss any? People seem to go nuts with ideas that you need to optimize every little thing without any evidence to show the significance of the impact on performance. Your example is perfect. Increasing the copper tube from 1/4 inch to even just 3/8 inch would more than make up for silver plating and not really cost that much more. There are guys who talk about using single piece, 3 inch copper tube bent into a loop to avoid having solder joints when using straight pieces even though those solder joints will be about the same resistance as a quarter inch of the tube or a microscopic increase in the resistance. Then they conveniently forget about the resistance of the clamp connection to the vacuum variable capacitor swamping out the solder joint resistance even more. It makes me want to scream, "Enough of the maddness"! You want to see guys reaching for lowest losses, highest Q, follow a crystal radio group. Some there claim Q's of 2000, (I believe them) Using 2 and 3 parallel pieces of 660/46 Litz wire. AMBCB. The 2000Q thread; http://tinyurl.com/q2hc6ga More info, or a way to get to page two and three; "Meanwhile, you can do the following search on Google: site:www.midnightscience.com/rapntap/ 2000Q If the main blue link doesn't work, then go down to the green link one line below, and the little drop down menu at the right, and select "cached" which will show you Google's cached copy of the page." I didn't know that Google trick! Recently a ferrite material out of China has made inductors hitting 1300 Q's easy. AMBCB http://theradioboard.com/rb/viewtopic.php?f=5&t=6259 Also rods of the same material. Mikek |
Flex dryer vent hose loop antenna
On 11/10/2015 12:40 PM, amdx wrote:
On 11/10/2015 9:30 AM, rickman wrote: On 11/10/2015 9:12 AM, amdx wrote: On 11/10/2015 1:41 AM, rickman wrote: On 11/9/2015 12:08 PM, amdx wrote: The silver is simply optimization. If you can make your coil wire 5% bigger, you should have already done that. Then if you want to optimized 1 + 0.05, silver plate it. Why can't you make the wire 5% bigger again? Where exactly is the cost? You can. I don't think ultimate optimizing is for you. Just make your coil with as much surface area as room will allow. Then know it could have just a tiny bit less loss if you had the silver. That tiny bit of loss will not be noticed in use, except for that little nagging thought... I once had a 6 or 7 turn loop made with 1/4" copper tubing*, Q was about 800 at 1MHz. I could have made it with 1/2" tubing, probably would have had higher Q. I guess the limits are money and how you want to limit physical size and maximum inductance you can use. Did I miss any? People seem to go nuts with ideas that you need to optimize every little thing without any evidence to show the significance of the impact on performance. Your example is perfect. Increasing the copper tube from 1/4 inch to even just 3/8 inch would more than make up for silver plating and not really cost that much more. There are guys who talk about using single piece, 3 inch copper tube bent into a loop to avoid having solder joints when using straight pieces even though those solder joints will be about the same resistance as a quarter inch of the tube or a microscopic increase in the resistance. Then they conveniently forget about the resistance of the clamp connection to the vacuum variable capacitor swamping out the solder joint resistance even more. It makes me want to scream, "Enough of the maddness"! You want to see guys reaching for lowest losses, highest Q, follow a crystal radio group. Some there claim Q's of 2000, (I believe them) Using 2 and 3 parallel pieces of 660/46 Litz wire. AMBCB. The 2000Q thread; http://tinyurl.com/q2hc6ga More info, or a way to get to page two and three; "Meanwhile, you can do the following search on Google: site:www.midnightscience.com/rapntap/ 2000Q If the main blue link doesn't work, then go down to the green link one line below, and the little drop down menu at the right, and select "cached" which will show you Google's cached copy of the page." I didn't know that Google trick! Recently a ferrite material out of China has made inductors hitting 1300 Q's easy. AMBCB http://theradioboard.com/rb/viewtopic.php?f=5&t=6259 Also rods of the same material. Crystal radio is a bit different. There your power source is the air waves, so a higher Q makes a difference. When transmitting with a 96% efficiency, using silver plating will only improve this to 96.2% at very best. Not really useful and likely not measurable. Better to deal with the significant losses like the extremely bad connection between the vacuum variable cap and the loop. Straps???!!! Get real! -- Rick |
Flex dryer vent hose loop antenna
On 11/10/2015 12:17 PM, Jeff Liebermann wrote:
On Tue, 10 Nov 2015 09:10:00 -0600, amdx wrote: My magloop nightmare come true: http://www.mixw.co.uk/MagLoop/magloopF.htm I don't get your point here. 1. It's not a fractal. 2. It's more like art than science. 3. It's a variation on my dryer vent hose antenna (tune by pounding). 4. It maximizes most of the worst characteristics of a loop, such as high length to surface area = low Q, small capture area, and optimized for low VSWR. 5. If you're worried about temperature drift, the lack of rigidity should make it drift even more. But you don't really know the details of how it works, so you don't know how well it can work other than by building it and testing. I haven't seen any reports that can be considered rigorous, but there is plenty of enthusiasm by the users. They think these antennas work well. Build one, monitor your dreams. My ego is too inflated to fit into the loop. I'll stick with the traditional colander on the head arrangement: https://www.google.com/search?q=colander+on+head&tbm=isch Are you making fun of religion now? Jeff, I don't like the parallel sections, seems like it could be made more complicated using x, y, and z right angles. Nap on that! :-) Mikek Sorry, but everything I've built that involves a 4th dimension has dissapeared when I applied power. The fields cancel and the entire antenna is sucked into the resultant vortex. Argh... I'm late again. Someday you'll be late for the last time and everyone will call you "late". -- Rick |
Flex dryer vent hose loop antenna
On 11/10/2015 11:40 AM, amdx wrote:
On 11/10/2015 9:30 AM, rickman wrote: On 11/10/2015 9:12 AM, amdx wrote: On 11/10/2015 1:41 AM, rickman wrote: On 11/9/2015 12:08 PM, amdx wrote: The silver is simply optimization. If you can make your coil wire 5% bigger, you should have already done that. Then if you want to optimized 1 + 0.05, silver plate it. Why can't you make the wire 5% bigger again? Where exactly is the cost? You can. I don't think ultimate optimizing is for you. Just make your coil with as much surface area as room will allow. Then know it could have just a tiny bit less loss if you had the silver. That tiny bit of loss will not be noticed in use, except for that little nagging thought... I once had a 6 or 7 turn loop made with 1/4" copper tubing*, Q was about 800 at 1MHz. I could have made it with 1/2" tubing, probably would have had higher Q. I guess the limits are money and how you want to limit physical size and maximum inductance you can use. Did I miss any? People seem to go nuts with ideas that you need to optimize every little thing without any evidence to show the significance of the impact on performance. Your example is perfect. Increasing the copper tube from 1/4 inch to even just 3/8 inch would more than make up for silver plating and not really cost that much more. There are guys who talk about using single piece, 3 inch copper tube bent into a loop to avoid having solder joints when using straight pieces even though those solder joints will be about the same resistance as a quarter inch of the tube or a microscopic increase in the resistance. Then they conveniently forget about the resistance of the clamp connection to the vacuum variable capacitor swamping out the solder joint resistance even more. It makes me want to scream, "Enough of the maddness"! You want to see guys reaching for lowest losses, highest Q, follow a crystal radio group. Some there claim Q's of 2000, (I believe them) Using 2 and 3 parallel pieces of 660/46 Litz wire. AMBCB. The 2000Q thread; http://tinyurl.com/q2hc6ga More info, or a way to get to page two and three; "Meanwhile, you can do the following search on Google: site:www.midnightscience.com/rapntap/ 2000Q If the main blue link doesn't work, then go down to the green link one line below, and the little drop down menu at the right, and select "cached" which will show you Google's cached copy of the page." I didn't know that Google trick! Recently a ferrite material out of China has made inductors hitting 1300 Q's easy. AMBCB http://theradioboard.com/rb/viewtopic.php?f=5&t=6259 Also rods of the same material. Mikek I'm curious about the 2000 Q restricting bandwidth. At 1MHz, the bandwidth would be only 500Hz. Does that affect the quality of the audio? That is, does it sound very bass-y? |
Flex dryer vent hose loop antenna
On Tue, 10 Nov 2015 16:09:51 -0500, rickman wrote:
But you don't really know the details of how it works, so you don't know how well it can work other than by building it and testing. I can get a clue on how well it works from an NEC2 model. However, this loop is easy. Remember your complaints about the relative merits of a circular loop, octagonal loop, square, and triangular loop? Well, this contrivance is a good example of a very shrunken loop, where the area enclosed by the loop has been minimized. Anyway, I'm a big fan of building something just to see what happens. It's part of "Learn by Destroying". I haven't seen any reports that can be considered rigorous, but there is plenty of enthusiasm by the users. They think these antennas work well. Yep. I also read the reviews on various products and usually find a few fanatics that will defend inferior junk to the death. It happens. However, I'm not talking about "these" antennas as in all types of loop antennas. I'm talking about this particular loop: http://www.mixw.co.uk/MagLoop/magloopF.htm My ego is too inflated to fit into the loop. I'll stick with the traditional colander on the head arrangement: https://www.google.com/search?q=colander+on+head&tbm=isch Are you making fun of religion now? I'm Jewish and occasionally wear a yarmulke (keepah or skull cap) which entitles me to some liberties in their design and operation. Full disclosu Mine is not lined with tin foil. Argh... I'm late again. Someday you'll be late for the last time and everyone will call you "late". Actually, I try to always be on time or a little early. In this case, it was for a ritual morning exercise trudge through the local state park. We usually have a small group that I didn't want to keep waiting. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
Flex dryer vent hose loop antenna
On Tue, 10 Nov 2015 11:40:43 -0600, amdx wrote:
You want to see guys reaching for lowest losses, highest Q, follow a crystal radio group. Some there claim Q's of 2000, (I believe them) Using 2 and 3 parallel pieces of 660/46 Litz wire. AMBCB. The 2000Q thread; http://tinyurl.com/q2hc6ga That's the unloaded Q measured in an HP4342A Q meter. Putting a load across the coil will drop the Q considerably. The equivalent parallel resistor across a perfect 120uHy inductor and resonating capacitor a R = Q * 2*Pi*f*L R = 2000 * 2 * 3.14 * 1*10^6 * 120*10^-6 R = 1.5Meg So, all it would take is a 1.5Meg load across the parallel coil and capacitor, and the Q would get cut in half. That doesn't sound very practical. I used an HP4342A at a former employer. Nice machine but really unstable for high-Q measurements. I'm not surprised that he had to leave it running for a while to stabilize: http://www.radiomuseum.org/r/hewlett_pa_q_meter_4342a4342.html $300 to $500 on eBay. Ouch. Drivel: The MFJ-259a is now fixed. It was the usual blown diodes, along with cleaning up the mess left by the leaky batteries. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
Flex dryer vent hose loop antenna
On 11/10/2015 5:55 PM, John S wrote:
On 11/10/2015 11:40 AM, amdx wrote: Recently a ferrite material out of China has made inductors hitting 1300 Q's easy. AMBCB http://theradioboard.com/rb/viewtopic.php?f=5&t=6259 Also rods of the same material. Mikek I'm curious about the 2000 Q restricting bandwidth. At 1MHz, the bandwidth would be only 500Hz. Does that affect the quality of the audio? That is, does it sound very bass-y? At 60 kHz the bandwidth would be 30 Hz, perfect! Great SNR improvement. -- Rick |
Flex dryer vent hose loop antenna
On 11/10/2015 7:37 PM, Jeff Liebermann wrote:
On Tue, 10 Nov 2015 16:09:51 -0500, rickman wrote: But you don't really know the details of how it works, so you don't know how well it can work other than by building it and testing. I can get a clue on how well it works from an NEC2 model. However, this loop is easy. Remember your complaints about the relative merits of a circular loop, octagonal loop, square, and triangular loop? Well, this contrivance is a good example of a very shrunken loop, where the area enclosed by the loop has been minimized. That is an assumption since you are analyzing it as a simple, circular loop which it is not. NEC2 may or may not be adequate to model it. Someone posted that they get significantly different results from two different simulators under some conditions. Anyway, I'm a big fan of building something just to see what happens. It's part of "Learn by Destroying". I haven't seen any reports that can be considered rigorous, but there is plenty of enthusiasm by the users. They think these antennas work well. Yep. I also read the reviews on various products and usually find a few fanatics that will defend inferior junk to the death. It happens. However, I'm not talking about "these" antennas as in all types of loop antennas. I'm talking about this particular loop: http://www.mixw.co.uk/MagLoop/magloopF.htm My ego is too inflated to fit into the loop. I'll stick with the traditional colander on the head arrangement: https://www.google.com/search?q=colander+on+head&tbm=isch Are you making fun of religion now? I'm Jewish and occasionally wear a yarmulke (keepah or skull cap) which entitles me to some liberties in their design and operation. Full disclosu Mine is not lined with tin foil. I'm referring to the Pastafarians of which I am a member. Argh... I'm late again. Someday you'll be late for the last time and everyone will call you "late". Actually, I try to always be on time or a little early. In this case, it was for a ritual morning exercise trudge through the local state park. We usually have a small group that I didn't want to keep waiting. I mean "late as in *the late* Dentarthurdent". -- Rick |
Flex dryer vent hose loop antenna
On 11/10/2015 4:55 PM, John S wrote:
On 11/10/2015 11:40 AM, amdx wrote: On 11/10/2015 9:30 AM, rickman wrote: On 11/10/2015 9:12 AM, amdx wrote: On 11/10/2015 1:41 AM, rickman wrote: On 11/9/2015 12:08 PM, amdx wrote: The silver is simply optimization. If you can make your coil wire 5% bigger, you should have already done that. Then if you want to optimized 1 + 0.05, silver plate it. Why can't you make the wire 5% bigger again? Where exactly is the cost? You can. I don't think ultimate optimizing is for you. Just make your coil with as much surface area as room will allow. Then know it could have just a tiny bit less loss if you had the silver. That tiny bit of loss will not be noticed in use, except for that little nagging thought... I once had a 6 or 7 turn loop made with 1/4" copper tubing*, Q was about 800 at 1MHz. I could have made it with 1/2" tubing, probably would have had higher Q. I guess the limits are money and how you want to limit physical size and maximum inductance you can use. Did I miss any? People seem to go nuts with ideas that you need to optimize every little thing without any evidence to show the significance of the impact on performance. Your example is perfect. Increasing the copper tube from 1/4 inch to even just 3/8 inch would more than make up for silver plating and not really cost that much more. There are guys who talk about using single piece, 3 inch copper tube bent into a loop to avoid having solder joints when using straight pieces even though those solder joints will be about the same resistance as a quarter inch of the tube or a microscopic increase in the resistance. Then they conveniently forget about the resistance of the clamp connection to the vacuum variable capacitor swamping out the solder joint resistance even more. It makes me want to scream, "Enough of the maddness"! You want to see guys reaching for lowest losses, highest Q, follow a crystal radio group. Some there claim Q's of 2000, (I believe them) Using 2 and 3 parallel pieces of 660/46 Litz wire. AMBCB. The 2000Q thread; http://tinyurl.com/q2hc6ga More info, or a way to get to page two and three; "Meanwhile, you can do the following search on Google: site:www.midnightscience.com/rapntap/ 2000Q If the main blue link doesn't work, then go down to the green link one line below, and the little drop down menu at the right, and select "cached" which will show you Google's cached copy of the page." I didn't know that Google trick! Recently a ferrite material out of China has made inductors hitting 1300 Q's easy. AMBCB http://theradioboard.com/rb/viewtopic.php?f=5&t=6259 Also rods of the same material. Mikek I'm curious about the 2000 Q restricting bandwidth. At 1MHz, the bandwidth would be only 500Hz. Does that affect the quality of the audio? That is, does it sound very bass-y? Jeff explained the loading, but I'll add, the rest of the circuitry to extract the audio signal and drive the headphones to create sound drops the Q. It can be as bad as a 2000 ohm headphone or as good as a transformer with very high input impedance, over 1.5 Megaohms according to Ben Tongue. http://www.bentongue.com/xtalset/5hpXform/5hpXform.html All 29 of his crystal radio research papers are here. http://www.bentongue.com/xtalset/xtalset.html Tremendous resource for Crystal Radio devotees. Mikek |
Flex dryer vent hose loop antenna
On 11/10/2015 2:36 PM, rickman wrote:
On 11/10/2015 12:40 PM, amdx wrote: When transmitting with a 96% efficiency, using silver plating will only improve this to 96.2% at very best. Not really useful and likely not measurable. Better to deal with the significant losses like the extremely bad connection between the vacuum variable cap and the loop. Straps???!!! Get real! Where did you get 96% efficient? From the site below. "The efficiency of a magnetic loop antenna is typically calculated as (Smith, 2006); efficiency=Rr/(Rr+Rhf2) Rr=radiation resistance (ohms) Rhf2=RF losses from combined skin effect and proximity effect (ohms) This term is not adjusted for the effects of ground or nearby objects." This builder has a different design. http://gridtoys.com/glen/loop/loop3.html You'll enjoy this line on his page. "*Aluminum works well in magnetic loop antennas. Yes, pure copper is a little better, but in multiple conductor magnetic loop antennas, there may be difficulty getting a copper loop to support its own weight. Structurally, aluminum is a lot better. Just make the conductors bigger." Mikek |
Flex dryer vent hose loop antenna
On 11/11/2015 6:59 AM, amdx wrote:
On 11/10/2015 2:36 PM, rickman wrote: On 11/10/2015 12:40 PM, amdx wrote: When transmitting with a 96% efficiency, using silver plating will only improve this to 96.2% at very best. Not really useful and likely not measurable. Better to deal with the significant losses like the extremely bad connection between the vacuum variable cap and the loop. Straps???!!! Get real! Where did you get 96% efficient? PFA It is an example of an efficient loop. Work with a less efficient loop and the sliver still makes only a small difference, less than the raw 5% difference in conductivity. From the site below. "The efficiency of a magnetic loop antenna is typically calculated as (Smith, 2006); efficiency=Rr/(Rr+Rhf2) Rr=radiation resistance (ohms) Rhf2=RF losses from combined skin effect and proximity effect (ohms) This term is not adjusted for the effects of ground or nearby objects." Your point? BTW, Rhf2 I believe is intended to be the resistive losses after considering the skin and proximity effects. As you can see, a 5% difference in Rhf2 will be less than 5% in the efficiency and depending on the numbers, much less. If you are working at very low efficiencies, then yes, a 5% difference in Rhf2 will result in a noticeable difference in efficiency, but this would be improved much more by using a good design rather than a poor one. Silver plating a crap antenna will still give you a crap antenna. This builder has a different design. http://gridtoys.com/glen/loop/loop3.html You'll enjoy this line on his page. "*Aluminum works well in magnetic loop antennas. Yes, pure copper is a little better, but in multiple conductor magnetic loop antennas, there may be difficulty getting a copper loop to support its own weight. Structurally, aluminum is a lot better. Just make the conductors bigger." Not sure what he is talking about. He seems to have screwed up the formulas calcuating the skin effect. I can't reconcile his math. -- Rick |
Flex dryer vent hose loop antenna
You analysis of the accordion roughness' effect is relative to the wavelength. I have no idea of the relationship, but my brother whom has designed antenna systems for military aircraft and patented antenna designs schooled on the fact that the formulas we all love and use are WRONG!
However, the formulas we use work well because we typically use relatively thin radiating elements compared to the wavelength, often significantly less than 1% of the operating frequency. The correct formula is surface area of the radiating element NOT LENGTH. To you and I building wire, Yagi, and loop antenna with skinny radiating elements length ends up being very close to the surface area. However, design an antenna for a cellphone from a thin plate or part of an aircraft fuselage and the length formula starts falling apart, especially at the higher frequencies. I didn't bother learning the correct formula as it is a little more complex.. I think it may come up when you start building fractal shaped antennas, such as were used in WWII by underground operatives using the lead frames stained glass windows in churches as radiating elements. The surface area formula may become relavent to magnetic loops with radiating loops with very thick radiators. N4VEP |
| All times are GMT +1. The time now is 09:09 AM. |
|
Powered by vBulletin® Copyright ©2000 - 2025, Jelsoft Enterprises Ltd.
RadioBanter.com