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Is It double bazooka less noisy?
Dear friends
It is usually said (in my country) that the double bazooka antenna is less noisy than a standard dipole. I think that there are not good reasons that endorse such a statement for noises coming from the far field (maybe it has some advantage with near field noises or maybe because its frequency response cures some pitfails of the associated receiver). I have looked for information in the net about this topica but I have not been lucky. I suppose that you have treated this topic at some time. If you can point me to a link to read about I would be very grateful to you. Also if you can give me your opinion in this respect. Thank you very much in advance Miguel (LU 6ETJ) |
Is It double bazooka less noisy?
lu6etj wrote:
I have looked for information in the net about this topica but I have not been lucky. Try http://www.w2du.com/r2ch18.pdf Being lossy reduces the noise but not the signal to noise ratio. -- 73, Cecil http://www.qsl.net/w5dxp |
Is It double bazooka less noisy?
lu6etj wrote: Dear friends It is usually said (in my country) that the double bazooka antenna is less noisy than a standard dipole. I think that there are not good reasons that endorse such a statement for noises coming from the far field (maybe it has some advantage with near field noises or maybe because its frequency response cures some pitfails of the associated receiver). I tested an IAC double bazooka, and it is no different than a regular dipole. It has very slightly less signal level, and very slightly more bandwidth. Not enough to worry about. No measurable difference in noise. 73 Tom |
Is It double bazooka less noisy?
wrote in message oups.com... lu6etj wrote: Dear friends It is usually said (in my country) that the double bazooka antenna is less noisy than a standard dipole. I think that there are not good reasons that endorse such a statement for noises coming from the far field (maybe it has some advantage with near field noises or maybe because its frequency response cures some pitfails of the associated receiver). I tested an IAC double bazooka, and it is no different than a regular dipole. It has very slightly less signal level, and very slightly more bandwidth. Not enough to worry about. No measurable difference in noise. 73 Tom We beat bazookas to death here years ago. Don't waste your time. 73 H. NQ5H |
Is It double bazooka less noisy?
Dear friends: Thank you very much for your answers. First of all: I agree with you, but my agreement is inductive, not experimental because I have not made my homework with that antenna... .. I knew the excellent article of Walter Maxwell, I am a fan of Maxwell, (both Maxwells) from their famous article "Another look on reflections" But do I think: is it possible that all those friends that are enthusiastic of the bazooka are affirming foolishness? They say: -With the bazooka we listen stations that we don't with the plain dipole, and this affirmatiotn point to a better SNR... I think that it must have something true behind so many similar statements. In the radio club of my area they say to have compared one against another with clearly favorable results to the bazooka. I thought...: A plain dipole is not a monoband antenna, it is, in fact, a multiband antenna, it receives all the frequencies. But do let us imagine a plain dipole that had connected on its terminals a couple high Q tuned circuits. That system it would be really "monoband"... then, if we connect such a system to a poor receiver Would not it improve the reception perhaps?, eliminating by that way possible saturation sources or intermodulación noises. Such a system, empirically it would seem a practically "more silent antenna" and it would explain, perhaps, the some results obtained by the colleagues. I say this because it is said that the bazooka possesses a syntony effect that transforms it into a true monoband device (I am not sure of it). It is only an arbitrary example of possible alternative explanations that, without violating the fundamental principles, can be compatibilized with the experiences of so many colleagues that sympathize with this antennas(some of which deserve my technical respect). I thank all your answers but I continue to the search of some explanation that endorses all the facts, just as the formidable article of Walter in reference to its bandwidth... I am for sure some of you will be able to help me to find a convincing explanation. Thank you very much in adavnce Miguel Ghezzi (LU 6ETJ) |
Is It double bazooka less noisy?
Miguel
There are "eyewitness accounts" of all sorts of foolishness. If you build it perfectly a bazooka will show a decrease in SWR over a very small range either side of resonance (SWR = 1:1) when compared to a dipole. This is completely useless except as an academic exercise. Here's how it works: The antenna is a parallel-resonant network (the bazooka) in parallel with a series-resonant network(the dipole). The parallel resonant (tank circuit) network stores energy and will oscillate at it's DRIVEN frequency when driven near resonance, so it stores the energy that would otherwise be reflected as long as it oscillates. Go too far from resonance and it quits oscillating. This effect manifests itself at SWR of 1.2:1 or lower. It flattens the SWR curve very near resonance. The 2:1 bandwidth is unaffected except by the additional loss of the tank circuit sitting across the dipole feed point. What Walter Maxwell showed explicitly is that any increase in SWR bandwidth is entirely due to loss, if I recall correctly. So all the trouble of building a bazooka with both legs and the dipole resonant at exactly the same frequency is a waste of time. A simple dipole works a bit better and is *MUCH LESS* work and expen$e. 73 H. NQ5H "lu6etj" wrote in message oups.com... Dear friends: Thank you very much for your answers. First of all: I agree with you, but my agreement is inductive, not experimental because I have not made my homework with that antenna... .. I knew the excellent article of Walter Maxwell, I am a fan of Maxwell, (both Maxwells) from their famous article "Another look on reflections" But do I think: is it possible that all those friends that are enthusiastic of the bazooka are affirming foolishness? They say: -With the bazooka we listen stations that we don't with the plain dipole, and this affirmatiotn point to a better SNR... I think that it must have something true behind so many similar statements. In the radio club of my area they say to have compared one against another with clearly favorable results to the bazooka. I thought...: A plain dipole is not a monoband antenna, it is, in fact, a multiband antenna, it receives all the frequencies. But do let us imagine a plain dipole that had connected on its terminals a couple high Q tuned circuits. That system it would be really "monoband"... then, if we connect such a system to a poor receiver Would not it improve the reception perhaps?, eliminating by that way possible saturation sources or intermodulación noises. Such a system, empirically it would seem a practically "more silent antenna" and it would explain, perhaps, the some results obtained by the colleagues. I say this because it is said that the bazooka possesses a syntony effect that transforms it into a true monoband device (I am not sure of it). It is only an arbitrary example of possible alternative explanations that, without violating the fundamental principles, can be compatibilized with the experiences of so many colleagues that sympathize with this antennas(some of which deserve my technical respect). I thank all your answers but I continue to the search of some explanation that endorses all the facts, just as the formidable article of Walter in reference to its bandwidth... I am for sure some of you will be able to help me to find a convincing explanation. Thank you very much in adavnce Miguel Ghezzi (LU 6ETJ) |
Is It double bazooka less noisy?
lu6etj wrote:
But do I think: is it possible that all those friends that are enthusiastic of the bazooka are affirming foolishness? They say: -With the bazooka we listen stations that we don't with the plain dipole, and this affirmatiotn point to a better SNR... The Double Bazooka is probably quieter than a plain dipole because, unlike a plain dipole, there is a DC path between all points in the antenna thus minimizing the effects of precipitation static. -- 73, Cecil http://www.qsl.net/w5dxp |
Is It double bazooka less noisy?
"Cecil Moore" wrote in message y.net... lu6etj wrote: But do I think: is it possible that all those friends that are enthusiastic of the bazooka are affirming foolishness? They say: -With the bazooka we listen stations that we don't with the plain dipole, and this affirmatiotn point to a better SNR... The Double Bazooka is probably quieter than a plain dipole because, unlike a plain dipole, there is a DC path between all points in the antenna thus minimizing the effects of precipitation static. -- 73, Cecil http://www.qsl.net/w5dxp So a nice 2.5 K ohm resistor at the feed point of a dipole would be vastly less work. "With the bazooka we listen stations that we don't with the plain dipole" I doubt anyone can document that. |
Is It double bazooka less noisy?
H. Adam Stevens, NQ5H wrote:
"Cecil Moore" wrote in message The Double Bazooka is probably quieter than a plain dipole because, unlike a plain dipole, there is a DC path between all points in the antenna thus minimizing the effects of precipitation static. So a nice 2.5 K ohm resistor at the feed point of a dipole would be vastly less work. Yes, it has nothing to do with SWR or bandwidth. I reduced the precipitation static problem in the Arizona desert by going to a full wave 40m loop, the one on my web page. -- 73, Cecil http://www.qsl.net/w5dxp |
Is It double bazooka less noisy?
lu6etj wrote:
I think if this was the case would be enough to install on plain dipole a RF ckoke or standard trifilar balun + a ckoke to ground on de rig. what do you think about? I would like to see the noise comparisons among a Double Bazooka, a plain dipole, and a folded dipole. My Arizona desert precipitation problem certainly decreased when I went from a G5RV to a full-wave 40m loop. With the G5RV, one element was grounded through the coax shield and the other element was capacitor isolated from ground by a series cap in my transceiver. It arced at the coax connector and a choke did solve the arcing problem. -- 73, Cecil http://www.qsl.net/w5dxp |
Is It double bazooka less noisy?
Here in Buenos Aires (near de Atlantic Ocean and the River Plate) it is
a very humid area, our typical old wives phrase for all the illness is "lo que mata es la humedad" (what kills you is the humidity) ;) (R to Adam I don't see your 2k5 answer, and R also to your doubts about a documented quieter performance, well, I am just searching for a documented falsehood of these extended claims, hi hi) Another antenna very reputed here as "quieter" it is a simple triangular loop, similar to Cecil's example, maybe the static explanation is OK. But... very few days at the year we have low humidity climate. (I never have burn a FET o MOS IC by touch them in my 38 years of continuated activity in electronics, but, yes, I kill various equipments by invert its polarity :) ) Do you think that static precipitation it is a valid explanation in these conditions? cheers Miguel |
Is It double bazooka less noisy?
H. Adam Stevens, NQ5H wrote:
I knew the excellent article of Walter Maxwell, I am a fan of Maxwell, (both Maxwells) from their famous article "Another look on reflections" "Their" article? Walt has a ghost writer? -- 73 from Ian GM3SEK |
Is It double bazooka less noisy?
lu6etj wrote: Do you think that static precipitation it is a valid explanation in these conditions? No. It makes no difference at all. If you have a static build-up problem all you need do is install a leak resistance or a suitable RF choke to ground. One should have that in an antenna anyway. I have the choice of any antenna I want and unlimited space to install them. I often have several antenna types up for any one band at the very same time. I've had a coaxial dipole up along with another dipole the same height, and there is no noticeable difference in any aspect of performance. I've even removed the shorted wire connection (the center conductor connection past the feedpoint) and restored it, and the antenna performance remains virtually identical in both noise and bandwidth. 73 Tom |
Is It double bazooka less noisy?
wrote:
lu6etj wrote: Do you think that static precipitation it is a valid explanation in these conditions? No. It makes no difference at all. It certainly made a difference in the Arizona desert under conditions that cause precipitation static in a dipole with no DC path between the elements. Many hams have direct experience and have reported it. Here is a discussion of such over on eHam.net. http://www.eham.net/forums/Elmers/83...a978db4ce15751 If you have a static build-up problem all you need do is install a leak resistance or a suitable RF choke to ground. One should have that in an antenna anyway. But a lot of hams don't know that and run their dipoles with the two coax conductors DC isolated from each other. I'll bet the "plain dipoles" being described by lu6etj as noisy don't have a leak resistance. The Double Bazooka is automatically protected from static buildup between the elements as are loops, and folded dipoles. -- 73, Cecil http://www.qsl.net/w5dxp |
Is It double bazooka less noisy?
I think he's referring to the Maxwell of Maxwell's Equations.
"Ian White GM3SEK" wrote in message ... H. Adam Stevens, NQ5H wrote: I knew the excellent article of Walter Maxwell, I am a fan of Maxwell, (both Maxwells) from their famous article "Another look on reflections" "Their" article? Walt has a ghost writer? -- 73 from Ian GM3SEK |
Is It double bazooka less noisy?
Ian White GM3SEK wrote:
H. Adam Stevens, NQ5H wrote: I knew the excellent article of Walter Maxwell, I am a fan of Maxwell, (both Maxwells) from their famous article "Another look on reflections" "Their" article? Walt has a ghost writer? There's a false attribution above, Ian. It should be: "lu6etj" wrote: I knew the excellent article of Walter Maxwell, I am a fan of Maxwell, (both Maxwells) from their famous article "Another look on reflections" -- 73, Cecil http://www.qsl.net/w5dxp |
Is It double bazooka less noisy?
Ian White GM3SEK wrote:
H. Adam Stevens, NQ5H wrote: I knew the excellent article of Walter Maxwell, I am a fan of Maxwell, (both Maxwells) from their famous article "Another look on reflections" "Their" article? Walt has a ghost writer? It's the royal "their." 73, Tom Donaly, KA6RUH |
Is It double bazooka less noisy?
Cecil Moore wrote:
Ian White GM3SEK wrote: H. Adam Stevens, NQ5H wrote: I knew the excellent article of Walter Maxwell, I am a fan of Maxwell, (both Maxwells) from their famous article "Another look on reflections" "Their" article? Walt has a ghost writer? There's a false attribution above, Ian. It should be: "lu6etj" wrote: I knew the excellent article of Walter Maxwell, I am a fan of Maxwell, (both Maxwells) from their famous article "Another look on reflections" You're right, Cecil - my apologies to all concerned. -- 73 from Ian GM3SEK 'In Practice' columnist for RadCom (RSGB) http://www.ifwtech.co.uk/g3sek |
Is It double bazooka less noisy?
Hi Hi...
Don't forget I am argentine, here we speak spanish all the day, it is my own translation error of possesive case... "their" it is wrong , "his" is the correct.- "...from HIS famous article..." R? References to "both" Mawells, yes, James an Walter..., (thanks Adam) Miguel ----------------------- Tom Donaly ha escrito: Ian White GM3SEK wrote: H. Adam Stevens, NQ5H wrote: I knew the excellent article of Walter Maxwell, I am a fan of Maxwell, (both Maxwells) from their famous article "Another look on reflections" "Their" article? Walt has a ghost writer? It's the royal "their." 73, Tom Donaly, KA6RUH |
Is It double bazooka less noisy?
lu6etj wrote:
Don't forget I am argentine, here we speak spanish all the day, it is my own translation error of possesive case... "their" it is wrong , "his" is the correct.- "...from HIS famous article..." R? The negative comments occurred because of errors in the attribution of your posting. It wasn't your fault so please don't worry about it. Back to Double Bazookas: It is a well accepted fact that insulation reduces the precipitation static problem. So the Double Bazooka reduces the precipitation static in two ways. 1. DC path between elements, 2. Insulation. -- 73, Cecil http://www.qsl.net/w5dxp |
Is It double bazooka less noisy?
I A B tested a regular low dipole made from number 8 AWG bare wire
against a double bazooka. Even during severe weather there never was a difference in measureable noise levels. That's just from a direct observation over a long period of time between the two antenna types. There also was no measurable or noticeable difference in signal strength or bandwidth. 73 Tom |
Is It double bazooka less noisy?
wrote:
I A B tested a regular low dipole made from number 8 AWG bare wire against a double bazooka. Even during severe weather there never was a difference in measureable noise levels. Did you A B test them under precipitation static conditions? If not, the test was incomplete. There is obviously a charged particle difference between a bare wire dipole and a double bazooka. If you weren't testing using charged particles, the test was just as obviously incomplete. -- 73, Cecil http://www.qsl.net/w5dxp |
Is It double bazooka less noisy?
Cecil Moore wrote: wrote: I A B tested a regular low dipole made from number 8 AWG bare wire against a double bazooka. Even during severe weather there never was a difference in measureable noise levels. Did you A B test them under precipitation static conditions? If not, the test was incomplete. There is obviously a charged particle difference between a bare wire dipole and a double bazooka. If you weren't testing using charged particles, the test was just as obviously incomplete. Cecil, There is absolutely no reason to believe that one antenna is less responsive to charged particle noise than the other. Whether or not the antenna can accumulate a static charge is a separate issue. 73, ac6xg |
Is It double bazooka less noisy?
Jim Kelley wrote:
There is absolutely no reason to believe that one antenna is less responsive to charged particle noise than the other. What about all the web references that say precipitation static can be decreased by insulating the antenna from the charged particles in the air? Think about it. A charged particle hitting a bare wire will likely transfer a charge. A charged particle hitting an insulated wire may or may not transfer a charge depending upon the insulation. After all, air is an insulator. A charged particle missing the antenna entirely is in contact with that air insulator. -- 73, Cecil http://www.qsl.net/w5dxp |
Is It double bazooka less noisy?
"Cecil Moore" wrote in message . com... Jim Kelley wrote: There is absolutely no reason to believe that one antenna is less responsive to charged particle noise than the other. What about all the web references that say precipitation static can be decreased by insulating the antenna from the charged particles in the air? Think about it. A charged particle hitting a bare wire will likely transfer a charge. A charged particle hitting an insulated wire may or may not transfer a charge depending upon the insulation. After all, air is an insulator. A charged particle missing the antenna entirely is in contact with that air insulator. -- 73, Cecil http://www.qsl.net/w5dxp I once had a ladder line fed doublet. It was disconnected at the feedthroughs because a thunderstorm was about ten miles North. I could pull 1 inch arcs off the feedthroughs to a grounded wire. Made me think of Ben Franklin. 73 H. NQ5H |
Is It double bazooka less noisy?
H. Adam Stevens, NQ5H wrote:
"Cecil Moore" wrote in message . com... Jim Kelley wrote: There is absolutely no reason to believe that one antenna is less responsive to charged particle noise than the other. What about all the web references that say precipitation static can be decreased by insulating the antenna from the charged particles in the air? Think about it. A charged particle hitting a bare wire will likely transfer a charge. A charged particle hitting an insulated wire may or may not transfer a charge depending upon the insulation. After all, air is an insulator. A charged particle missing the antenna entirely is in contact with that air insulator. -- 73, Cecil http://www.qsl.net/w5dxp I once had a ladder line fed doublet. It was disconnected at the feedthroughs because a thunderstorm was about ten miles North. I could pull 1 inch arcs off the feedthroughs to a grounded wire. Made me think of Ben Franklin. 73 H. NQ5H A man could get killed fooling with that kind of stuff. It's a wonder Ben lived as long as he did. 73, Tom Donaly, KA6RUH |
Is It double bazooka less noisy?
"Cecil Moore" wrote in message
. com... Jim Kelley wrote: There is absolutely no reason to believe that one antenna is less responsive to charged particle noise than the other. What about all the web references that say precipitation static can be decreased by insulating the antenna from the charged particles in the air? I refuse to take responsibility for the things other people say. :-) Think about it. A charged particle hitting a bare wire will likely transfer a charge. A charged particle hitting an insulated wire may or may not transfer a charge depending upon the insulation. Consider the nature of dielectric materials. I could be wrong, but I bet if you stuck a negative oxygen ion on the outside of a jacketed conductor, you could make the conductor inside think you had put an electron directly on it. After all, air is an insulator. A charged particle missing the antenna entirely is in contact with that air insulator. And air, which is an insulator, is also in contact with a bare wire antenna - presumably 'insulating' it. The difference is one of density (and dielectric constant). I suppose if you set up a big electric or magnetic field in the proper orientation, you could make a lot of the ions go away from an antenna. But controlling plasmas is kinda like herding cats. 73, ac6xg |
Is It double bazooka less noisy?
"Jim Kelley" wrote in message ... "Cecil Moore" wrote in message . com... Jim Kelley wrote: There is absolutely no reason to believe that one antenna is less responsive to charged particle noise than the other. What about all the web references that say precipitation static can be decreased by insulating the antenna from the charged particles in the air? I refuse to take responsibility for the things other people say. :-) Think about it. A charged particle hitting a bare wire will likely transfer a charge. A charged particle hitting an insulated wire may or may not transfer a charge depending upon the insulation. Consider the nature of dielectric materials. I could be wrong, but I bet if you stuck a negative oxygen ion on the outside of a jacketed conductor, you could make the conductor inside think you had put an electron directly on it. After all, air is an insulator. A charged particle missing the antenna entirely is in contact with that air insulator. And air, which is an insulator, is also in contact with a bare wire antenna - presumably 'insulating' it. The difference is one of density (and dielectric constant). I suppose if you set up a big electric or magnetic field in the proper orientation, you could make a lot of the ions go away from an antenna. But controlling plasmas is kinda like herding cats. 73, ac6xg My first physics job was in fusion. Herding cats is trivial. 73 H. NQ5H PS I like my SteppIR. Now THAT's broadband and insulated. |
Is It double bazooka less noisy?
H. Adam Stevens, NQ5H wrote:
I once had a ladder line fed doublet. It was disconnected at the feedthroughs because a thunderstorm was about ten miles North. I could pull 1 inch arcs off the feedthroughs to a grounded wire. Made me think of Ben Franklin. For sure, a gradient is established by thunderstorms resulting in all sorts of electrical and magnetic phenomena. But the particular type of noise I am talking about is precipitation static caused by charged particles hitting a bare wire dipole when one element of the dipole is floating. In particular, this type of noise can occur in the Arizona desert when there is not a cloud in the sky. Here is how "precipitation static" is defined: http://www.atis.org/tg2k/_precipitation_static.html "ATIS is a United States based body that is committed to rapidly developing and promoting technical and operations standards for the communications and related information technologies industry worldwide using a pragmatic, flexible and open approach. ATIS is accredited by the American National Standards Institute (ANSI)." -- 73, Cecil http://www.qsl.net/w5dxp |
Is It double bazooka less noisy?
Jim Kelley wrote:
Consider the nature of dielectric materials. I could be wrong, but I bet if you stuck a negative oxygen ion on the outside of a jacketed conductor, you could make the conductor inside think you had put an electron directly on it. The question is whether the electron stays on the insulation or migrates through it to the conductor. The size of the charge Vs the dielectric determines how much of the charge actually reaches the conductor. When I went from bare wire to 600v insulation, my precipitation static problems decreased considerably. Then when I went to 1000v insulation and a full wave loop, most of my precipitation static problems disappeared. The worst case of precipitation static seems to be for airplane antennas. Insulation is the recommended cure although folding is also mentioned. Please do a web search for "precipitation static" and see for yourself. http://www.atis.org/tg2k/_precipitation_static.html -- 73, Cecil http://www.qsl.net/w5dxp |
Is It double bazooka less noisy?
Cecil Moore wrote:
Jim Kelley wrote: Consider the nature of dielectric materials. I could be wrong, but I bet if you stuck a negative oxygen ion on the outside of a jacketed conductor, you could make the conductor inside think you had put an electron directly on it. The question is whether the electron stays on the insulation or migrates through it to the conductor. Actually, the question is whether or not one can hear the resulting noise. The size of the charge Vs the dielectric determines how much of the charge actually reaches the conductor. Perhaps you mean the amount of charge Vs. the dielectric determine the voltage. When I went from bare wire to 600v insulation, my precipitation static problems decreased considerably. Then when I went to 1000v insulation and a full wave loop, most of my precipitation static problems disappeared. I see your point. The poorer the dielectric and the greater it's thickness, the lower the induced voltage. There should be some effect, yes. What'd you use, 20 meters of CRT anode wire or spark plug wire? :-) The point with which Tom seemed to take issue was the implication that an antenna with low DC resistance would have lower precipitation static noise. I also disagree with that notion. The worst case of precipitation static seems to be for airplane antennas. Insulation is the recommended cure although folding is also mentioned. Please do a web search for "precipitation static" and see for yourself. http://www.atis.org/tg2k/_precipitation_static.html I'm glad we agree on the definitions. In one of your previous references I noted the term precipitation static used (incorrectly) to describe the noise associated with static discharge. This is a distinction I attempted to point out in my earlier post. Precipitation, among other things, can cause charge to accumulate on objects which are insulated from ground. This accumulation can continue to increase until breakdown occurs, causing a spark and a noise which is big enough to knock down the receiver AGC for a few seconds (or worse). Precipitation static is the noise which is apparent when a relatively high flux of ions impinges upon an antenna. Low DC impedance antennas won't accumulate large amounts of charge or generate a static discharge, but they are nevertheless sensitive to the static noise just as any other antenna would be. In other words, you and Tom W8JI are both right - you just don't know why. ;-) Did you see the article in Harper's magazine on W6AM? Pretty neat. Even that article mentioned precipitation static. 73, ac6xg |
Is It double bazooka less noisy?
Jim Kelley wrote:
Cecil Moore wrote: The size of the charge Vs the dielectric determines how much of the charge actually reaches the conductor. Perhaps you mean the amount of charge Vs. the dielectric determine the voltage. size = amount = magnitude = amplitude. It is hard to visualize how a charge could make it to the conductor without the migration of a quantum particle. The point with which Tom seemed to take issue was the implication that an antenna with low DC resistance would have lower precipitation static noise. I also disagree with that notion. Both of you misunderstood the definition of "noise" that I was using. With the feedline completely disconnected from the transceiver, arcing occurred and that aural noise woke me up at night. It was aural noise from the arcing caused by precipitation static charge tansfer that woke me up and a low DC resistance eliminated it. Precipitation static is the noise which is apparent when a relatively high flux of ions impinges upon an antenna. Low DC impedance antennas won't accumulate large amounts of charge or generate a static discharge, but they are nevertheless sensitive to the static noise just as any other antenna would be. In other words, you and Tom W8JI are both right - you just don't know why. ;-) When a charge hits a closed loop, there are two paths it can take to equalize the charge around the loop. Only one of those paths is through the receiver and that is a higher impedance path than the other path. When a single-wire dipole needs to equalize the charges between the dipole elements, there is only one path available - through the receiver which often has a capacitor in series and thus blocks DC charge equalization. This is, of course, not the only reason that a loop is quieter than a single-wire dipole but is simply one of the reasons. Incidentally, "Quietflex" antenna wire, with its 1000v insulation reduced the problem to an acceptable level in the Arizona desert. I still use that wire for my dipoles. -- 73, Cecil http://www.qsl.net/w5dxp |
Is It double bazooka less noisy?
For the past few days we had rain and lighting. Prior to any rain
hitting my antennas the steeady background noise hissing came up. The noise came up first on my high dipoles, two regular dipoles at 150-160 feet. One was bare #14 copperweld, the other is insulated #10. they were both equal as near as I could tell. It came up the same but later in time on my three low 80 meter dipole antennas at about the same rate. Two were bare wire and one was a coaxial double bazooka. All are at about 35-40 feet high. I have a 1/4 wl shorted stub I use as a second harmonic trap on 80 meters. It switches in and out with a relay on an RCS-8V switch that selects trunk lines to antennas. I pulled the relay wire off, and the 80 meter dipoles had then same steady noise as with the stub in. The dc path had no effect at all on steady noise, but on the high dipoles, both the insulated one and bare one, there was a popping noise about once every second or two that went away with the dipoles center conductor grounded. I could hear this popping noise on any antenna near the dipoles. I added a 470K resistor to the 80M feedlines and the popping noise quit. I removed it and added a choke and the popping noise quit. When lightning would hit the popping noise would quit for a while, and then come back. As the storm got worse the noise got worse. When the rain was very heavy and lightning very close, I stopped for a while. At that point the noise was terrible on all antennas, but definately worse in level on the high antennas. It was no better and no worse on any antenna at the same height. All through this my IAC double bazooka was no quieter than a regular dipole made from #16 bare copper located 100 feet away at the same height. This test was with all antennas in place at the same time on the same day in the same weather. 73 Tom |
Is It double bazooka less noisy?
wrote:
All through this my IAC double bazooka was no quieter than a regular dipole made from #16 bare copper located 100 feet away at the same height. This test was with all antennas in place at the same time on the same day in the same weather. Precipitation static doesn't always occur during thunderstorms. It's effects are greatly reduced in high humidity environments. For precipitation static to occur requires charged particles. And you don't know if charged particles even existed during your experiment. To separate charged particle effects from lightning effects you need to run your experiment without the clouds and thunderstorms under conditions that guarantee charged particles. That would be during a dust storm on a clear sky day under low humidity conditions as often exist in Queen Creek, AZ. Precipitation static is a large problem for airplanes but only when they are flying through a field of charged particles. One of the treatments for precipitation static on airplane antennas is to insulate the antenna inside a non-conductive pipe. Another treatment is to fold the antenna. These are well known, well accepted methods of reducing precipitation static problems on airplane antennas. You can verify those facts for yourself through a little web research. -- 73, Cecil http://www.qsl.net/w5dxp |
Is It double bazooka less noisy?
wrote:
... but on the high dipoles, both the insulated one and bare one, there was a popping noise about once every second or two that went away with the dipoles center conductor grounded. All through this my IAC double bazooka was no quieter than a regular dipole made from #16 bare copper located 100 feet away at the same height. I forgot to ask. Did the double bazooka arc like the ungrounded dipoles? -- 73, Cecil http://www.qsl.net/w5dxp |
Is It double bazooka less noisy?
Cecil Moore wrote:
Precipitation static doesn't always occur during thunderstorms. It's effects are greatly reduced in high humidity environments. For precipitation static to occur requires charged particles. And you don't know if charged particles even existed during your experiment. To separate charged particle effects from lightning effects you need to run your experiment without the clouds and thunderstorms under conditions that guarantee charged particles. That would be during a dust storm on a clear sky day under low humidity conditions as often exist in Queen Creek, AZ. Cecil, This is close to being an all-time RRAA classic. Precipitation, at least in the form of rain, often occurs when the humidity is quite high. Do you suppose they should have named it dust storm static rather than precipitation static? Or perhaps dry rain static? 8-) 73, Gene W4SZ |
Is It double bazooka less noisy?
Gene Fuller wrote:
Precipitation, at least in the form of rain, often occurs when the humidity is quite high. Yes, and triboelectric charging is known to be magnitudes worse in low humidity conditions. On this web page: http://www.esda.org/basics/part1.cfm it says that a worker at a bench can expect 6000v when the relative humidity is 10-25% Vs 100v when the relative humidity is 65-90%. Do you suppose they should have named it dust storm static rather than precipitation static? Or perhaps dry rain static? "Charged particle" static would have been more descriptive since "precipitation" is most associated with falling H2O. If the relative humidity is 10% when the rain starts falling, seems the precipitation static would be worse than if the relative humidity was 90% when the rain started falling. Dry snow falling in low relative humidity conditions could certainly carry large charges. Dry wind driven dust particles in low relative humidity conditions are often associated with precipitation static. But assuming that raindrops falling in high humidity conditions are electrically charged is a questionable assumption. And trying to detect precipitation static noise in the presence of lightning seems like looking for a needle in a haystack. It is good engineering practice to try to isolate what one is trying to measure. The best way I know of to isolate precipitation static from other noise sources is to perform the measurements under clear sky, windy, low humidity conditions in the desert. I strongly suspect that w8ji didn't detect any of the arcing noise in the double bazooka that he detected in the bare wire ungrounded dipoles. Was that a noise reduction? -- 73, Cecil http://www.qsl.net/w5dxp |
Is It double bazooka less noisy?
This is hilarious.
No matter in what context, it appears bazookas cause long threads. 73 H., NQ5H |
Is It double bazooka less noisy?
H. Adam Stevens, NQ5H wrote:
This is hilarious. No matter in what context, it appears bazookas cause long threads. I don't remember the bazooka ever being discussed before in the context of precipitation static so it is essentially a brand new topic. -- 73, Cecil http://www.qsl.net/w5dxp |
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