Re: AX1 Loaded Whip Antenna - Elevation and
Locked
12
12
Re: AX1 Loaded Whip Antenna - Elevation and
 
|
Dave's observation is about how the antenna actually works, as
determined by Mother Nature, and, depending how the antenna is rigged, he's probably right. Antennas work by carrying RF current, any end fed radiator needs a counterpoise, which, because it's carrying the same RF current as the end fed radiator, CAN ALSO RADIATE. Indeed, this antenna, depending on how it's deployed, can be thought of as an off-center fed dipole. Back when I lived in Chicago, I had another "ad hoc" antenna that was effective on 80 and 160M. My shack was on the second floor, the antenna was a loaded resonant dipole tuned to 80 and 40 that sort of worked on 30 and 15, and was fed by vintage 75 ohm Belden "kilowatt twin lead." To use it on 160M, I ran two wires down to both sides of a wrought iron fence that ran around my front yard (both sides because it was broken by a gate). The wire and the fence functioned as a counterpoise, and the vertical wires radiated (and modified the resonance). As it turned out, that antenna loaded that way worked better on 80 than it did loaded as dipole, simply because the dipole wasn't very high (35-40 ft). I'm reminded that my buddy KK9H used the air conditioning ducts in his home as a counterpoise on 160M. We've worked several times since I moved to W6. There are photos and a description of my Chicago antenna weedpatch (won't dignify it by calling it an antenna farm) in http://k9yc.com/LimitedSpaceAntennasPPT.pdf 73, Jim K9YC On 8/27/2019 12:38 PM, Grant Youngman wrote: > But I fail to see the rationale of using the AX1 as a “counterpoise”. > For quick low profile portable, the AX1 works as well as you can expect a very short loaded radiator to work. For that purpose it’s easy, quick on the air, and does fine. ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
Re: AX1 Loaded Whip Antenna - Elevation and
|
|
In reply to this post by Grant Youngman-2
The point you're missing is that the AX1 wants (needs) a wire counterpoise to work very well at all, and since it's that counterpoise wire that is doing most of the actual radiating you're better off trying to optimize what you do with it. I don't see how that is so difficult to understand, especially since there have been several testimonials here that say the same thing ... the AX1 works much better when you keep the wire "counterpoise" (actually the primary radiator) as straight and in the clear as possible. 73, Dave AB7E On 8/27/2019 12:38 PM, Grant Youngman wrote: > Not trying to start a disagreement here, but I don’t see the point. > > If you want to run a wire antenna, then, good gracious, run a wire antenna. They work pretty well portable. I carry two in my bag. But I fail to see the rationale of using the AX1 as a “counterpoise”. > For quick low profile portable, the AX1 works as well as you can expect a very short loaded radiator to work. For that purpose it’s easy, quick on the air, and does fine. > > Grant NQ5T > KX3 (8342)/KXPA100 > > >>> I think users of the AX1 would be better off thinking of IT as the counterpoise, and making the most out of what they normally consider to be the counterpoise wire. >>> > \ > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[hidden email] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to [hidden email] ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
Re: AX1 Loaded Whip Antenna - Elevation and
|
|
I don’t think I’m missing anything. You’re basically arguing for an elevated counterpoise. Of course the AX1 needs a counterpoise. And I run an elevated counterpoise on most of my portable vertical antennas.
My 31’ portable wire works better than an AX1 most of the time. It’s not always convenient or possible to put a wire in a tree. And a wire counterpoise for your AX1, 3-5’ off the ground, straight as an arrow, won’t radiate much anyway (although it can help adjust the native imdedance of the AX1/counterpoise system). When I walk to the dock, I take the AX1 and the recommended counterpoise. The counterpoise goes over the end of the dock — no trees down there :-) I’m not saying that an elevated counterpoise won’t work with the AX1, just that I’m having trouble getting my head around considering the wire as the main radiator, and the AX1 as a counterpoise??? Grant NQ5T KX3 (8342)/KXPA100 > On Aug 27, 2019, at 4:31 PM, David Gilbert <[hidden email]> wrote: > > > The point you're missing is that the AX1 wants (needs) a wire counterpoise to work very well at all, and since it's that counterpoise wire that is doing most of the actual radiating you're better off trying to optimize what you do with it. I don't see how that is so difficult to understand, especially since there have been several testimonials here that say the same thing ... the AX1 works much better when you keep the wire "counterpoise" (actually the primary radiator) as straight and in the clear as possible. > > 73, > Dave AB7E > > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
Re: AX1 Loaded Whip Antenna - Elevation and
|
|
It is easy to cancel the radiation from the 'counterpoise' - use 2 equal
length wires running in opposite directions from the base. The horizontal radiation from each will cancel, and all you have left is the loaded vertical radiator to radiate with vertical polarization. If they are on the ground, the cancellation may not be as uniform. For further information read the section on verticals in any Antenna Handbook - even my Antenna Handbook from the late 1950s cover it. 73, Don W3FPR On 8/27/2019 5:29 PM, Grant Youngman wrote: > I don’t think I’m missing anything. You’re basically arguing for an elevated counterpoise. Of course the AX1 needs a counterpoise. And I run an elevated counterpoise on most of my portable vertical antennas. > > My 31’ portable wire works better than an AX1 most of the time. It’s not always convenient or possible to put a wire in a tree. And a wire counterpoise for your AX1, 3-5’ off the ground, straight as an arrow, won’t radiate much anyway (although it can help adjust the native imdedance of the AX1/counterpoise system). When I walk to the dock, I take the AX1 and the recommended counterpoise. The counterpoise goes over the end of the dock — no trees down there :-) > > I’m not saying that an elevated counterpoise won’t work with the AX1, just that I’m having trouble getting my head around considering the wire as the main radiator, and the AX1 as a counterpoise??? > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
Re: AX1 Loaded Whip Antenna - Elevation and
|
|
In reply to this post by Grant Youngman-2
Yes, of course. I know how things work. And I agree with Don’s comment that came in in another email while I was typing. That does NOT mean the vertical element is the “counterpoise" to a long elevated wire (or more than one) a few feet off the ground. Yes those wires may radiate, but probably not where you want them to, unless you want to talk straight up.
Like I’ve argued, if you want a wire to radiate, put in in the air. And if you do that, there’s no point in having the AX1 in the system. That’s all. Over and out, SK :-) Grant NQ5T KX3 (8342)/KXPA100 > On Aug 27, 2019, at 5:34 PM, Bob McGraw K4TAX <[hidden email]> wrote: > > The "wire" is just the other 1/2 of the dipole. > > 73 > > Bob, K4TAX > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
Re: AX1 Loaded Whip Antenna - Elevation and
|
|
In reply to this post by Grant Youngman-2
I'll try not to beat this into the ground here, but I think the physics here is important. As K9YC said in his reply to you, equal currents go in both directions from the feedpoint ... to the AX1 and to the counterpoise wire. That's simply physics, and it's true unless currents on the shield of the coax cause imbalance ... in which case the coax is doing a bunch of radiating. Now then, what is important is what happens to those equal currents. It doesn't matter if one side of the feedpoint is the AX1 or if it is the "counterpoise" wire ... they are both simply loads as far as the feedpoint is concerned. Read that again ... it is THE critical concept. Current generates a radiated field. That is simple physics. Resistive loss dissipates energy instead of radiating it. That is also basic physics. To a lesser extent, current distributed over a longer length is a more effective radiator than a shorter length even disregarding impedance concerns. Consequently, a short, lossy "load" is going to radiate less RF than a longer, less lossy "load". Straighter is better than snaky. All of that is fact. Unless you have a very short counterpoise wire it is going to try to do a better job of radiating RF than the AX1 if you give it a chance. Keep it as straight as possible and keep it clear of ground and other RF dissipating structures. That doesn't mean that the AX1 isn't serving a very useful purpose. It is. It is allowing you to feed current into the "counterpoise" wire with a reasonable feedpoint impedance. That's critical. But it doesn't mean that the AX1 is doing the bulk of the radiating unless you aren't using a counterpoise at all. Hope this helps. 73, Dave AB7E On 8/27/2019 2:29 PM, Grant Youngman wrote: > > I’m not saying that an elevated counterpoise won’t work with the AX1, just that I’m having trouble getting my head around considering the wire as the main radiator, and the AX1 as a counterpoise??? > > Grant NQ5T > KX3 (8342)/KXPA100 > > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
Re: AX1 Loaded Whip Antenna - Elevation and
|
Administrator
|
I'm generally walking when I use the AX1 (pedestrian mobile, or /PM). It isn't possible to elevate the radial under these circumstances; it drags on the ground. The whip is the radiator.
Wayne N6KR > On Aug 27, 2019, at 3:05 PM, David Gilbert <[hidden email]> wrote: > > > I'll try not to beat this into the ground here, but I think the physics here is important. > > As K9YC said in his reply to you, equal currents go in both directions from the feedpoint ... to the AX1 and to the counterpoise wire. That's simply physics, and it's true unless currents on the shield of the coax cause imbalance ... in which case the coax is doing a bunch of radiating. > > Now then, what is important is what happens to those equal currents. It doesn't matter if one side of the feedpoint is the AX1 or if it is the "counterpoise" wire ... they are both simply loads as far as the feedpoint is concerned. Read that again ... it is THE critical concept. > > Current generates a radiated field. That is simple physics. Resistive loss dissipates energy instead of radiating it. That is also basic physics. To a lesser extent, current distributed over a longer length is a more effective radiator than a shorter length even disregarding impedance concerns. Consequently, a short, lossy "load" is going to radiate less RF than a longer, less lossy "load". Straighter is better than snaky. All of that is fact. > > Unless you have a very short counterpoise wire it is going to try to do a better job of radiating RF than the AX1 if you give it a chance. Keep it as straight as possible and keep it clear of ground and other RF dissipating structures. > > That doesn't mean that the AX1 isn't serving a very useful purpose. It is. It is allowing you to feed current into the "counterpoise" wire with a reasonable feedpoint impedance. That's critical. But it doesn't mean that the AX1 is doing the bulk of the radiating unless you aren't using a counterpoise at all. > > Hope this helps. 73, > Dave AB7E > > > > > On 8/27/2019 2:29 PM, Grant Youngman wrote: >> >> I’m not saying that an elevated counterpoise won’t work with the AX1, just that I’m having trouble getting my head around considering the wire as the main radiator, and the AX1 as a counterpoise??? >> >> Grant NQ5T >> KX3 (8342)/KXPA100 >> >> > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[hidden email] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to [hidden email] ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
Re: AX1 Loaded Whip Antenna - Elevation and
|
Administrator
|
And I've worked all over the world with 5 or 10 watts doing it :)
Wayne > On Aug 27, 2019, at 4:07 PM, Wayne Burdick <[hidden email]> wrote: > > I'm generally walking when I use the AX1 (pedestrian mobile, or /PM). It isn't possible to elevate the radial under these circumstances; it drags on the ground. The whip is the radiator. > > Wayne > N6KR > > > >> On Aug 27, 2019, at 3:05 PM, David Gilbert <[hidden email]> wrote: >> >> >> I'll try not to beat this into the ground here, but I think the physics here is important. >> >> As K9YC said in his reply to you, equal currents go in both directions from the feedpoint ... to the AX1 and to the counterpoise wire. That's simply physics, and it's true unless currents on the shield of the coax cause imbalance ... in which case the coax is doing a bunch of radiating. >> >> Now then, what is important is what happens to those equal currents. It doesn't matter if one side of the feedpoint is the AX1 or if it is the "counterpoise" wire ... they are both simply loads as far as the feedpoint is concerned. Read that again ... it is THE critical concept. >> >> Current generates a radiated field. That is simple physics. Resistive loss dissipates energy instead of radiating it. That is also basic physics. To a lesser extent, current distributed over a longer length is a more effective radiator than a shorter length even disregarding impedance concerns. Consequently, a short, lossy "load" is going to radiate less RF than a longer, less lossy "load". Straighter is better than snaky. All of that is fact. >> >> Unless you have a very short counterpoise wire it is going to try to do a better job of radiating RF than the AX1 if you give it a chance. Keep it as straight as possible and keep it clear of ground and other RF dissipating structures. >> >> That doesn't mean that the AX1 isn't serving a very useful purpose. It is. It is allowing you to feed current into the "counterpoise" wire with a reasonable feedpoint impedance. That's critical. But it doesn't mean that the AX1 is doing the bulk of the radiating unless you aren't using a counterpoise at all. >> >> Hope this helps. 73, >> Dave AB7E >> >> >> >> >> On 8/27/2019 2:29 PM, Grant Youngman wrote: >>> >>> I’m not saying that an elevated counterpoise won’t work with the AX1, just that I’m having trouble getting my head around considering the wire as the main radiator, and the AX1 as a counterpoise??? >>> >>> Grant NQ5T >>> KX3 (8342)/KXPA100 >>> >>> >> >> ______________________________________________________________ >> Elecraft mailing list >> Home: http://mailman.qth.net/mailman/listinfo/elecraft >> Help: http://mailman.qth.net/mmfaq.htm >> Post: mailto:[hidden email] >> >> This list hosted by: http://www.qsl.net >> Please help support this email list: http://www.qsl.net/donate.html >> Message delivered to [hidden email] > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
Re: AX1 Loaded Whip Antenna - Elevation and
|
|
In reply to this post by wayne burdick
What makes you think the wire isn't doing the bulk of the radiating just because it drags across the ground? Actual RF ground is usually some distance below the surface, sometimes several feet. There is a way to prove me wrong on all of this. Connect two AX1's to a Tee connector coming directly out of the rig. Position them vertically so that they act like a vertical dipole. Use the rig's antenna tuner to make sure full power is getting to the combination. Have somebody measure the signal strength at different positions around a circle some distance from the rig/antenna. Now replace the lower AX1 with the recommended 13' piece of wire, again using the antenna tuner to hopefully feed the same amount of power to the AX1. Take the same signal strength measurements ... again around the circle in order to try to take into account any directionality of the wire if it isn't mostly vertical. If the AX1 by itself was doing most of the radiating the 2nd AX1 would be a better counterpoise than the wire. That's not debatable. 73, Dave AB7E On 8/27/2019 4:07 PM, Wayne Burdick wrote: > I'm generally walking when I use the AX1 (pedestrian mobile, or /PM). It isn't possible to elevate the radial under these circumstances; it drags on the ground. The whip is the radiator. > > Wayne > N6KR > > > >> On Aug 27, 2019, at 3:05 PM, David Gilbert <[hidden email]> wrote: >> >> >> I'll try not to beat this into the ground here, but I think the physics here is important. >> >> As K9YC said in his reply to you, equal currents go in both directions from the feedpoint ... to the AX1 and to the counterpoise wire. That's simply physics, and it's true unless currents on the shield of the coax cause imbalance ... in which case the coax is doing a bunch of radiating. >> >> Now then, what is important is what happens to those equal currents. It doesn't matter if one side of the feedpoint is the AX1 or if it is the "counterpoise" wire ... they are both simply loads as far as the feedpoint is concerned. Read that again ... it is THE critical concept. >> >> Current generates a radiated field. That is simple physics. Resistive loss dissipates energy instead of radiating it. That is also basic physics. To a lesser extent, current distributed over a longer length is a more effective radiator than a shorter length even disregarding impedance concerns. Consequently, a short, lossy "load" is going to radiate less RF than a longer, less lossy "load". Straighter is better than snaky. All of that is fact. >> >> Unless you have a very short counterpoise wire it is going to try to do a better job of radiating RF than the AX1 if you give it a chance. Keep it as straight as possible and keep it clear of ground and other RF dissipating structures. >> >> That doesn't mean that the AX1 isn't serving a very useful purpose. It is. It is allowing you to feed current into the "counterpoise" wire with a reasonable feedpoint impedance. That's critical. But it doesn't mean that the AX1 is doing the bulk of the radiating unless you aren't using a counterpoise at all. >> >> Hope this helps. 73, >> Dave AB7E >> >> >> >> >> On 8/27/2019 2:29 PM, Grant Youngman wrote: >>> I’m not saying that an elevated counterpoise won’t work with the AX1, just that I’m having trouble getting my head around considering the wire as the main radiator, and the AX1 as a counterpoise??? >>> >>> Grant NQ5T >>> KX3 (8342)/KXPA100 >>> >>> >> ______________________________________________________________ >> Elecraft mailing list >> Home: http://mailman.qth.net/mailman/listinfo/elecraft >> Help: http://mailman.qth.net/mmfaq.htm >> Post: mailto:[hidden email] >> >> This list hosted by: http://www.qsl.net >> Please help support this email list: http://www.qsl.net/donate.html >> Message delivered to [hidden email] > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
Re: AX1 Loaded Whip Antenna - Elevation and
|
Administrator
|
Guys - lots of very good info here, but we are beating this into the ground.
Lets end thread thread for now in the interest of maintaining a reasonable list SNR. ;-) Go out and operate, experiment with antennas, including the AX1, and see what has been discussed in this thread is best for you in your operating situations. And of course, have fun! 73, Eric Moderator, Mooderator and sometimes, List Therapist.. elecraft.com --- Sent from my iPhone 6S > On Aug 27, 2019, at 4:28 PM, David Gilbert <[hidden email]> wrote: > > > What makes you think the wire isn't doing the bulk of the radiating just because it drags across the ground? Actual RF ground is usually some distance below the surface, sometimes several feet. > > There is a way to prove me wrong on all of this. Connect two AX1's to a Tee connector coming directly out of the rig. Position them vertically so that they act like a vertical dipole. Use the rig's antenna tuner to make sure full power is getting to the combination. Have somebody measure the signal strength at different positions around a circle some distance from the rig/antenna. > > Now replace the lower AX1 with the recommended 13' piece of wire, again using the antenna tuner to hopefully feed the same amount of power to the AX1. Take the same signal strength measurements ... again around the circle in order to try to take into account any directionality of the wire if it isn't mostly vertical. > > If the AX1 by itself was doing most of the radiating the 2nd AX1 would be a better counterpoise than the wire. That's not debatable. > > 73, > Dave AB7E > > >> On 8/27/2019 4:07 PM, Wayne Burdick wrote: >> I'm generally walking when I use the AX1 (pedestrian mobile, or /PM). It isn't possible to elevate the radial under these circumstances; it drags on the ground. The whip is the radiator. >> >> Wayne >> N6KR >> >> >> >>> On Aug 27, 2019, at 3:05 PM, David Gilbert <[hidden email]> wrote: >>> >>> >>> I'll try not to beat this into the ground here, but I think the physics here is important. >>> >>> As K9YC said in his reply to you, equal currents go in both directions from the feedpoint ... to the AX1 and to the counterpoise wire. That's simply physics, and it's true unless currents on the shield of the coax cause imbalance ... in which case the coax is doing a bunch of radiating. >>> >>> Now then, what is important is what happens to those equal currents. It doesn't matter if one side of the feedpoint is the AX1 or if it is the "counterpoise" wire ... they are both simply loads as far as the feedpoint is concerned. Read that again ... it is THE critical concept. >>> >>> Current generates a radiated field. That is simple physics. Resistive loss dissipates energy instead of radiating it. That is also basic physics. To a lesser extent, current distributed over a longer length is a more effective radiator than a shorter length even disregarding impedance concerns. Consequently, a short, lossy "load" is going to radiate less RF than a longer, less lossy "load". Straighter is better than snaky. All of that is fact. >>> >>> Unless you have a very short counterpoise wire it is going to try to do a better job of radiating RF than the AX1 if you give it a chance. Keep it as straight as possible and keep it clear of ground and other RF dissipating structures. >>> >>> That doesn't mean that the AX1 isn't serving a very useful purpose. It is. It is allowing you to feed current into the "counterpoise" wire with a reasonable feedpoint impedance. That's critical. But it doesn't mean that the AX1 is doing the bulk of the radiating unless you aren't using a counterpoise at all. >>> >>> Hope this helps. 73, >>> Dave AB7E >>> >>> >>> >>> >>>> On 8/27/2019 2:29 PM, Grant Youngman wrote: >>>> I’m not saying that an elevated counterpoise won’t work with the AX1, just that I’m having trouble getting my head around considering the wire as the main radiator, and the AX1 as a counterpoise??? >>>> >>>> Grant NQ5T >>>> KX3 (8342)/KXPA100 >>>> >>>> >>> ______________________________________________________________ >>> Elecraft mailing list >>> Home: http://mailman.qth.net/mailman/listinfo/elecraft >>> Help: http://mailman.qth.net/mmfaq.htm >>> Post: mailto:[hidden email] >>> >>> This list hosted by: http://www.qsl.net >>> Please help support this email list: http://www.qsl.net/donate.html >>> Message delivered to [hidden email] >> > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[hidden email] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to [hidden email] Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
«
Return to Elecraft
|
1 view|%1 views
| Free forum by Nabble | Edit this page |