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#11
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That's what I had in mind but experiment. You never know.
CW KC7NOD "dxAce" wrote in message ... bpnjensen wrote: Hi, folks (and maybe CW) - on his helpful hints pages, CW (kc7nod) recommends the possible use of a balun (which I take to mean a transformer?) at the coax-antenna junction of a loop antenna... http://www.kc7nod.20m.com/loop.htm In this instance, can anyone advise what the ratio on this would be? 4:1? Another value? I'd like to try out this antenna design, and the balun idea too. My guess would be a 1:1 balun. ( I hope this is not a quiz) ;-) dxAce |
#13
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Telamon wrote in message ...
In article , (bpnjensen) wrote: (RHF) wrote in message . com... BJ, I would venture to say 'if' you are using the Loop Antenna for both Receiving and Transmission then a 1:1 or 2:1 Balun would work well with a Coax Cable Lead-in-Line. An Antenna Tuner would be required for Multi-Band operation. "IF" the Loop Antenna is going to be used as a Receive "Only" Antenna with a Coax Cable Feed-in-Line; then a 4:1 or even a 9:1 Balun could be used with good Multi-Band results. ~ RHF Thanks RHF, and everyone else too - these are great ideas and links. I have managed to obtain quite good results on most of the bands from 6 MHz and up, and so I was going to concentrate my efforts with this loop on the tropicals. I was going to start with about 220' of wire in a loop around my rooftop and off into some backyard trees. Based on what I've seen here and on the websites, it looks as though a 2:1 balun might be perfect, but a 4:1 may work about as well for a slightly broader frequency coverage on a receive-only antenna; so I may try these two first and then compare. One website says not to use a balun at all (why?), so maybe I'll try it unmatched too. The impedance changes according to the length of the loop relative to the wavelength received. A full wave length loop within a wavelength of ground is around 100 ohms so you would want to use a 2:1 BALUN to 50 ohm coax. If the loop is closer to half wave length then it will be closer to 50 ohms and you would want to use a 1:1 BALUN. Thanks for this, Telamon - I intend to use this antenna for reception only on several lower frequency HF bands (really about 3 through 6 MHz), so I'm not sure that I want or need a BALUN/transformer that will match the impedance so closely. Ultimately, I may end up extending the length of the wire up to 340 feet and making it's shape weird so that it will fit in my limited space, just to see if I can achieve better results on 90m...but it weould still be used on 49, 60 and 75. Bruce Jensen |
#14
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bpnjensen wrote: Telamon wrote in message ... In article , (bpnjensen) wrote: (RHF) wrote in message . com... BJ, I would venture to say 'if' you are using the Loop Antenna for both Receiving and Transmission then a 1:1 or 2:1 Balun would work well with a Coax Cable Lead-in-Line. An Antenna Tuner would be required for Multi-Band operation. "IF" the Loop Antenna is going to be used as a Receive "Only" Antenna with a Coax Cable Feed-in-Line; then a 4:1 or even a 9:1 Balun could be used with good Multi-Band results. ~ RHF Thanks RHF, and everyone else too - these are great ideas and links. I have managed to obtain quite good results on most of the bands from 6 MHz and up, and so I was going to concentrate my efforts with this loop on the tropicals. I was going to start with about 220' of wire in a loop around my rooftop and off into some backyard trees. Based on what I've seen here and on the websites, it looks as though a 2:1 balun might be perfect, but a 4:1 may work about as well for a slightly broader frequency coverage on a receive-only antenna; so I may try these two first and then compare. One website says not to use a balun at all (why?), so maybe I'll try it unmatched too. The impedance changes according to the length of the loop relative to the wavelength received. A full wave length loop within a wavelength of ground is around 100 ohms so you would want to use a 2:1 BALUN to 50 ohm coax. If the loop is closer to half wave length then it will be closer to 50 ohms and you would want to use a 1:1 BALUN. Thanks for this, Telamon - I intend to use this antenna for reception only on several lower frequency HF bands (really about 3 through 6 MHz), so I'm not sure that I want or need a BALUN/transformer that will match the impedance so closely. Ultimately, I may end up extending the length of the wire up to 340 feet and making it's shape weird so that it will fit in my limited space, just to see if I can achieve better results on 90m...but it weould still be used on 49, 60 and 75. It has been my experience in years past that horizontal loops are great for close in work, say on 160, 75 and 80 meters. However, they do not seem to support long haul DX. And that is why many amateur users of those bands love them, makes for a great, close in range signal, firing up, and then down. Yes, great for reducing QRM sources, but that is because they concentrate on vertically arriving signals, rather than the more commonly horizontally polarized QRM. Now, if you had the loop in the vertical plane, that would of course change things dramatically. Just my opinion, of course. dxAce Michigan |
#15
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"dxAce" wrote in message ... | | | bpnjensen wrote: | | Telamon wrote in message ... | In article , | (bpnjensen) wrote: | | (RHF) wrote in message | . com... | | BJ, | | I would venture to say 'if' you are using the Loop Antenna for both | Receiving and Transmission then a 1:1 or 2:1 Balun would work well | with a Coax Cable Lead-in-Line. An Antenna Tuner would be required | for Multi-Band operation. | | "IF" the Loop Antenna is going to be used as a Receive "Only" | Antenna with a Coax Cable Feed-in-Line; then a 4:1 or even a 9:1 | Balun could be used with good Multi-Band results. | | ~ RHF | | Thanks RHF, and everyone else too - these are great ideas and links. | I have managed to obtain quite good results on most of the bands from | 6 MHz and up, and so I was going to concentrate my efforts with this | loop on the tropicals. I was going to start with about 220' of wire | in a loop around my rooftop and off into some backyard trees. | | Based on what I've seen here and on the websites, it looks as though | a 2:1 balun might be perfect, but a 4:1 may work about as well for a | slightly broader frequency coverage on a receive-only antenna; so I | may try these two first and then compare. One website says not to | use a balun at all (why?), so maybe I'll try it unmatched too. | | The impedance changes according to the length of the loop relative to | the wavelength received. A full wave length loop within a wavelength of | ground is around 100 ohms so you would want to use a 2:1 BALUN to 50 | ohm coax. If the loop is closer to half wave length then it will be | closer to 50 ohms and you would want to use a 1:1 BALUN. | | Thanks for this, Telamon - I intend to use this antenna for reception | only on several lower frequency HF bands (really about 3 through 6 | MHz), so I'm not sure that I want or need a BALUN/transformer that | will match the impedance so closely. Ultimately, I may end up | extending the length of the wire up to 340 feet and making it's shape | weird so that it will fit in my limited space, just to see if I can | achieve better results on 90m...but it weould still be used on 49, 60 | and 75. | | It has been my experience in years past that horizontal loops are great for close in work, say on 160, 75 and 80 meters. However, they do not seem to | support long haul DX. And that is why many amateur users of those bands love them, makes for a great, close in range signal, firing up, and then down. | | Yes, great for reducing QRM sources, but that is because they concentrate on vertically arriving signals, rather than the more commonly horizontally | polarized QRM. | | Now, if you had the loop in the vertical plane, that would of course change things dramatically. | | Just my opinion, of course. | | dxAce | Michigan From the FWIW Department, John Devoldere believes higher - angle angennas (esp. quarter - wave verticals) outperform low - angle antennas for greyline work, on the lower HF bands. Of course, that's only 30 minutes of a given day. 73, Steve Lawrence KAØPMD Burnsville, Minnesota "If a man wants his dreams to come true then he must wake up." - Anonymous --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.773 / Virus Database: 520 - Release Date: 10/5/04 |
#16
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In article , dxAce
wrote: bpnjensen wrote: Telamon wrote in message odigy.co m... In article , (bpnjensen) wrote: (RHF) wrote in message . com... BJ, I would venture to say 'if' you are using the Loop Antenna for both Receiving and Transmission then a 1:1 or 2:1 Balun would work well with a Coax Cable Lead-in-Line. An Antenna Tuner would be required for Multi-Band operation. "IF" the Loop Antenna is going to be used as a Receive "Only" Antenna with a Coax Cable Feed-in-Line; then a 4:1 or even a 9:1 Balun could be used with good Multi-Band results. ~ RHF Thanks RHF, and everyone else too - these are great ideas and links. I have managed to obtain quite good results on most of the bands from 6 MHz and up, and so I was going to concentrate my efforts with this loop on the tropicals. I was going to start with about 220' of wire in a loop around my rooftop and off into some backyard trees. Based on what I've seen here and on the websites, it looks as though a 2:1 balun might be perfect, but a 4:1 may work about as well for a slightly broader frequency coverage on a receive-only antenna; so I may try these two first and then compare. One website says not to use a balun at all (why?), so maybe I'll try it unmatched too. The impedance changes according to the length of the loop relative to the wavelength received. A full wave length loop within a wavelength of ground is around 100 ohms so you would want to use a 2:1 BALUN to 50 ohm coax. If the loop is closer to half wave length then it will be closer to 50 ohms and you would want to use a 1:1 BALUN. Thanks for this, Telamon - I intend to use this antenna for reception only on several lower frequency HF bands (really about 3 through 6 MHz), so I'm not sure that I want or need a BALUN/transformer that will match the impedance so closely. Ultimately, I may end up extending the length of the wire up to 340 feet and making it's shape weird so that it will fit in my limited space, just to see if I can achieve better results on 90m...but it weould still be used on 49, 60 and 75. It has been my experience in years past that horizontal loops are great for close in work, say on 160, 75 and 80 meters. However, they do not seem to support long haul DX. And that is why many amateur users of those bands love them, makes for a great, close in range signal, firing up, and then down. Yes, great for reducing QRM sources, but that is because they concentrate on vertically arriving signals, rather than the more commonly horizontally polarized QRM. Now, if you had the loop in the vertical plane, that would of course change things dramatically. Just my opinion, of course. I generally agree with what you stated. My horizontal loops generally seem to work better evenings as opposed to daytime where the lower frequencies are favored. Generally, I get a stronger signal response from a vertical loop daytime but they are directional where the horizontal loop is not. Remember that for a one-wavelength or more loop the response is in and out of the loop so a horizontal loop is looking straight up. The pattern changes, as the loop becomes half wave where the response is from the edge. For a fixed horizontal loop then at high frequencies it looks up and at low frequencies, it looks more toward the horizon in one direction. The BALUN will most likely only help you with local noise coming from the AC power through your radio up the coax to the antenna and then back to the radio input. -- Telamon Ventura, California |
#17
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= = = (bpnjensen) wrote in message
= = = . com... (RHF) wrote in message . com... BJ, I would venture to say 'if' you are using the Loop Antenna for both Receiving and Transmission then a 1:1 or 2:1 Balun would work well with a Coax Cable Lead-in-Line. An Antenna Tuner would be required for Multi-Band operation. "IF" the Loop Antenna is going to be used as a Receive "Only" Antenna with a Coax Cable Feed-in-Line; then a 4:1 or even a 9:1 Balun could be used with good Multi-Band results. ~ RHF Thanks RHF, and everyone else too - these are great ideas and links. I have managed to obtain quite good results on most of the bands from 6 MHz and up, and so I was going to concentrate my efforts with this loop on the tropicals. I was going to start with about 220' of wire in a loop around my rooftop and off into some backyard trees. Based on what I've seen here and on the websites, it looks as though a 2:1 balun might be perfect, but a 4:1 may work about as well for a slightly broader frequency coverage on a receive-only antenna; so I may try these two first and then compare. One website says not to use a balun at all (why?), so maybe I'll try it unmatched too. BJ, If you are planning on using the Loop Antenna for transmitting on one specific Amateur Band with a un-balanced or balance feed-line; and have cut and trimmed the Wire Loop Antenna Element for a very low SWR. Then a Balun would simply be source of power loss, and have no added value in getting your signal out (ERP). NOTE: These are sometimes called "SkyWire" Loop Antennas. You may wish to check-out the SkyWire Loop Antennas eGroup on YAHOO! SKYWIRE-LOOP= http://groups.yahoo.com/group/SkyWires/ iane ~ RHF .. .. I will post some observations when I get this thing up and running. Thanks! Bruce Jensen .. |
#18
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#19
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"Mark Keith" wrote: | Huh? A 1/4 wave vertical is a fairly low angle radiator. The better | the ground radial system, the better the low angle performance. The | max radiation of a 1/4 wave ground plane is under 5 degrees when it's | over a 1/2 wave up and has 4 radials. | If a 1/4 wave vertical is a higher angle radiator, what do you, or he, | consider a low angle radiator? MK A 1/2 wave vertical, or ideally, a 5/8 (.625) wavelength vertical, actually. I wasn't disputing the fact that a 1/4 wave vertical works very well for DX purposes, but was pointing out that there is an exception to every rule, and I found this particular "Exception" quite interesting. You can find a reference to the "high angle CAN be better for gray line work" phenomenon in one of the Twin Cities DX Association's newsletters: http://www.tcdxa.org/ The link appears under "TCDXA Info." Click on the "Gray Line Report." There are 3 newsletters on that particular page, and it's in there *somewhere* or other. VY 73, Steve Lawrence KAØPMD Burnsville, Minnesota "If a man wants his dreams to come true then he must wake up." - Anonymous --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.775 / Virus Database: 522 - Release Date: 10/8/04 |
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