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#1
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Michael wrote:
According to the ARRL handbook the highest gain is achieve with a 5/8ths wave spacing between the upper and lower elements. The handbook gives the following figures for estimated gain. 3/8 wave spacing = 4.4 dbd 1/2 wave spacing = 5.9 dbd 5/8 wave spacing = 6.7 dbd 3/4 wave spacing = 6.6 dbd It seems to works on 14 MHz (stacked dipoles at 14 MHz), but on 10 meters the single 10 meter dipole blows it away. Quoting the ARRL Antenna Book: "It should be designed for the higher of the two frequencies using 3/4 lamda spacing between parallel elements. It will then operate on the lower frequency ... with 3/8 lamda spacing. If you have 5/8 lamda spacing on 20m, you will have 5/4 lamda spacing on 10m with poor performance. -- 73, Cecil http://www.w5dxp.com |
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#2
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On Jul 5, 11:04 pm, Cecil Moore wrote:
Michael wrote: According to the ARRL handbook the highest gain is achieve with a 5/8ths wave spacing between the upper and lower elements. The handbook gives the following figures for estimated gain. 3/8 wave spacing = 4.4 dbd 1/2 wave spacing = 5.9 dbd 5/8 wave spacing = 6.7 dbd 3/4 wave spacing = 6.6 dbd It seems to works on 14 MHz (stacked dipoles at 14 MHz), but on 10 meters the single 10 meter dipole blows it away. Quoting the ARRL Antenna Book: "It should be designed for the higher of the two frequencies using 3/4 lamda spacing between parallel elements. It will then operate on the lower frequency ... with 3/8 lamda spacing. If you have 5/8 lamda spacing on 20m, you will have 5/4 lamda spacing on 10m with poor performance. -- 73, Cecil http://www.w5dxp.com Not only that, but will depend if feeding end fire, or broadside. It's only as a broadside array that max gain is at 5/8 wl spacing. And he is feeding his as an end fire array. The elements would need to be end to end IE: collinear, array to be fed as a broadside array. As an end fire, the spacing must be quite a bit closer. If I remember right, max gain with an end fire array is appx 1/8 wl spacing. But from my own experimenting around with them, it's not ultra critical as far as getting them to work. In my case, I was feeding each element with a separate feed line, and changing lengths to steer the array. It was quite crude, but worked pretty well. In my case, I tried to compromise on the spacing so I could feed it both end fire, and broadside. I think I used about 1/4 wl. I also used about the same scheme on 10m, using two 5/8 wl ground planes. I forgot the exact spacing I used. It was more dictated by available mast/.vent pipe locations more than trying to get an exact length. But it was a compromise spacing, and I fed it both ways depending on the pattern I wanted. |
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#3
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On Jul 6, 12:59 am, wrote:
But it was a compromise spacing, and I fed it both ways depending on the pattern I wanted. Just thinking about another thing.. I think feeding in phase would give a bi directional pattern, but if he wanted an omni directional pattern, I think he'd have to have the elements 90 degrees out of phase. But I fergot... He could fire up eznec demo or whatever and he can quickly get a pretty good idea what to expect in theory with any particular spacing and phasing. He could crudely steer the pattern if he used various length feeders to each element. Some also use the "L/C" phasing boxes to steer the pattern. Again fairly crude compared to some methods, but it will work. Just don't expect perfect textbook patterns. You have to take what you get... The ARRL antenna book has better methods if want cleaner patterns. |
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#4
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On Jul 6, 12:04 am, Cecil Moore wrote:
Michael wrote: According to the ARRL handbook the highest gain is achieve with a 5/8ths wave spacing between the upper and lower elements. The handbook gives the following figures for estimated gain. 3/8 wave spacing = 4.4 dbd 1/2 wave spacing = 5.9 dbd 5/8 wave spacing = 6.7 dbd 3/4 wave spacing = 6.6 dbd It seems to works on 14 MHz (stacked dipoles at 14 MHz), but on 10 meters the single 10 meter dipole blows it away. Quoting the ARRL Antenna Book: "It should be designed for the higher of the two frequencies using 3/4 lamda spacing between parallel elements. It will then operate on the lower frequency ... with 3/8 lamda spacing. If you have 5/8 lamda spacing on 20m, you will have 5/4 lamda spacing on 10m with poor performance. -- 73, Cecil http://www.w5dxp.com It is designed for the higher band. |
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#5
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On Jul 5, 12:42 pm, Michael wrote:
I've seen the Lazy H mentioned in many antenna books over the years, so I decided to try one on 10 meters. According to the ARRL handbook the Lazy H is two collinear elements stacked on above the other, Each collinear element is made up of two 1/2 wave elements. I chose to use 5/8 wave spacing between the top and bottom elements. I connected the top and bottom elements with 450 ohm 16 gauge stranded ladder line (window line). After building the antenna I verified connectivity between the top and bottom right elements and the top and bottom left elements. I color coded the end insulators on each side so I could easily see which top and bottom elements were connected to each other. The antenna book says to connect the 450 ohm ladder line from the antenna tuner to the middle of the 450 ladder line that connects top and bottom elements. Ok done. Now I put up the antenna and make sure the top and bottom elements are in phase. That is both left connected elements are on the left and both right connected element are on the right. I also make sure there is no twist in the ladder line connecting the top and bottom elements. I also checked the other ends of the 450 ohm ladder line feeding the antenna has connectivity at the antenna, and the left and right sides of the ladder line do not have connectivity. The 450 ohm ladder line feeding the antenna is about 200 feet long. Now I bring the 450 ohm feedline in to the house, hook it to my Dentron MT-2000 antenna tuner with the 4:1 balun inside, tune it up, and it sucks! Both my half wave horizontal dipole and my Solarcon Max-2000 blow it away on incoming skip even in the preferred direction of the lazy H. I rechecked my connections and the lengths of the elements and spacing and they are correct. I did take in to account the velocity factor of the 450 ladder line that connects the top elements to the bottom elements. The antenna book says the length of the 450 ladder lien between the antenna and the antenna tuner can e any lenght. The bottom element is at least 1/2 wave of the ground, and the top element is 5/8ths wave above that. What did I do wrong? Michael I found an article that shows using a 1/4 wave matching stub at the bottom of an end fire Lazy H with 1/2 wave spacing. Perhaps even ladder line transmission line needs a matching stub. http://www.ve7zsa.net/technical/advs...ntenna_r00.htm |
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#6
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On Jul 6, 1:55 pm, Michael wrote:
On Jul 5, 12:42 pm, Michael wrote: I've seen the Lazy H mentioned in many antenna books over the years, so I decided to try one on 10 meters. According to the ARRL handbook the Lazy H is two collinear elements stacked on above the other, Each collinear element is made up of two 1/2 wave elements. I chose to use 5/8 wave spacing between the top and bottom elements. I connected the top and bottom elements with 450 ohm 16 gauge stranded ladder line (window line). After building the antenna I verified connectivity between the top and bottom right elements and the top and bottom left elements. I color coded the end insulators on each side so I could easily see which top and bottom elements were connected to each other. The antenna book says to connect the 450 ohm ladder line from the antenna tuner to the middle of the 450 ladder line that connects top and bottom elements. Ok done. Now I put up the antenna and make sure the top and bottom elements are in phase. That is both left connected elements are on the left and both right connected element are on the right. I also make sure there is no twist in the ladder line connecting the top and bottom elements. I also checked the other ends of the 450 ohm ladder line feeding the antenna has connectivity at the antenna, and the left and right sides of the ladder line do not have connectivity. The 450 ohm ladder line feeding the antenna is about 200 feet long. Now I bring the 450 ohm feedline in to the house, hook it to my Dentron MT-2000 antenna tuner with the 4:1 balun inside, tune it up, and it sucks! Both my half wave horizontal dipole and my Solarcon Max-2000 blow it away on incoming skip even in the preferred direction of the lazy H. I rechecked my connections and the lengths of the elements and spacing and they are correct. I did take in to account the velocity factor of the 450 ladder line that connects the top elements to the bottom elements. The antenna book says the length of the 450 ladder lien between the antenna and the antenna tuner can e any lenght. The bottom element is at least 1/2 wave of the ground, and the top element is 5/8ths wave above that. What did I do wrong? Michael I found an article that shows using a 1/4 wave matching stub at the bottom of an end fire Lazy H with 1/2 wave spacing. Perhaps even ladder line transmission line needs a matching stub. http://www.ve7zsa.net/technical/advs...ntenna_r00.htm Looks like another user had similar problems with a Lazy H using 450 ladder line all the way to the tuner. Like me his will tune on 14 MHz where it is basically stacked dipoles, but once you get to 10 meters it is a no go. He tried 450 ohm ladder line to a balun as well. http://forums.qrz.com/archive/index.php/t-135914.html |
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#7
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On Jul 6, 1:55 pm, Michael wrote:
On Jul 5, 12:42 pm, Michael wrote: I've seen the Lazy H mentioned in many antenna books over the years, so I decided to try one on 10 meters. According to the ARRL handbook the Lazy H is two collinear elements stacked on above the other, Each collinear element is made up of two 1/2 wave elements. I chose to use 5/8 wave spacing between the top and bottom elements. I connected the top and bottom elements with 450 ohm 16 gauge stranded ladder line (window line). After building the antenna I verified connectivity between the top and bottom right elements and the top and bottom left elements. I color coded the end insulators on each side so I could easily see which top and bottom elements were connected to each other. The antenna book says to connect the 450 ohm ladder line from the antenna tuner to the middle of the 450 ladder line that connects top and bottom elements. Ok done. Now I put up the antenna and make sure the top and bottom elements are in phase. That is both left connected elements are on the left and both right connected element are on the right. I also make sure there is no twist in the ladder line connecting the top and bottom elements. I also checked the other ends of the 450 ohm ladder line feeding the antenna has connectivity at the antenna, and the left and right sides of the ladder line do not have connectivity. The 450 ohm ladder line feeding the antenna is about 200 feet long. Now I bring the 450 ohm feedline in to the house, hook it to my Dentron MT-2000 antenna tuner with the 4:1 balun inside, tune it up, and it sucks! Both my half wave horizontal dipole and my Solarcon Max-2000 blow it away on incoming skip even in the preferred direction of the lazy H. I rechecked my connections and the lengths of the elements and spacing and they are correct. I did take in to account the velocity factor of the 450 ladder line that connects the top elements to the bottom elements. The antenna book says the length of the 450 ladder lien between the antenna and the antenna tuner can e any lenght. The bottom element is at least 1/2 wave of the ground, and the top element is 5/8ths wave above that. What did I do wrong? Michael I found an article that shows using a 1/4 wave matching stub at the bottom of an end fire Lazy H with 1/2 wave spacing. Perhaps even ladder line transmission line needs a matching stub. http://www.ve7zsa.net/technical/advs...ntenna_r00.htm Yep. Looks like that is it. Unfortunately I am out of time for this weekend, so I'll have to try it out next weekend. According to an article I found I need a closed end 1/4 matching stub. I'll update here after I try it out next weekend. -Michael |
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#8
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The bottom element is at least 1/2 wave of the ground, and the top
element is 5/8ths wave above that. What did I do wrong? I suspect with your long feedline length (200 ft you said?), and the probably very high SWR on the feedline, you have significant feedline loss. Also, are the elements really horizontal? Or are they closer to inverted V's? Tor N4OGW |
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#9
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