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#11
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Michael wrote:
On Jul 5, 10:44 pm, "Hal Rosser" wrote: I'm not sure, but if the Lazy H has Horizontal polarity and the folks you're trying to communicate with are using Verticals, there may be quite a bit of signal loss. Since you mentioned it was for 11 meters, can we assume you're trying to communicate without using 'skip'? It meant for skip. I mean to type 10 meters. Old habits die hard as I started on the CB band. . In my area, San Joaquin Valley, Ca--most 10m is on verticals ... while the guys running the "one size fits all" antennas--or, 80-10m (or, even 160-10m!) are mostly horiz--since a 10m is so easy, they slap up a 10m vertical also. The "myth" that most noise is vertically polarized--well, I never subscribed to that (but, when I was a kid, I first believed it!) Most runs off above ground power-lines are even, somewhere, around a 45 degree angle (and, above ground power-lines are ALWAYS horiz polarized! Drive around and look, maybe they do it different in your area ... ??? And, now, most power-lines have went under-ground in my area ... vertical is fine with me and I don't send my signal skyward or into the ground, where it may reflect into the stratosphere anyway ... Regards, JS |
#12
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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 |
#13
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John Smith wrote:
Michael wrote: On Jul 5, 10:44 pm, "Hal Rosser" wrote: I'm not sure, but if the Lazy H has Horizontal polarity and the folks you're trying to communicate with are using Verticals, there may be quite a bit of signal loss. Since you mentioned it was for 11 meters, can we assume you're trying to communicate without using 'skip'? It meant for skip. I mean to type 10 meters. Old habits die hard as I started on the CB band. . In my area, San Joaquin Valley, Ca--most 10m is on verticals ... while the guys running the "one size fits all" antennas--or, 80-10m (or, even 160-10m!) are mostly horiz--since a 10m is so easy, they slap up a 10m vertical also. The "myth" that most noise is vertically polarized--well, I never subscribed to that (but, when I was a kid, I first believed it!) Most runs off above ground power-lines are even, somewhere, around a 45 degree angle (and, above ground power-lines are ALWAYS horiz polarized! Drive around and look, maybe they do it different in your area ... ??? And, now, most power-lines have went under-ground in my area ... vertical is fine with me and I don't send my signal skyward or into the ground, where it may reflect into the stratosphere anyway ... Regards, JS And, I almost forgot, ever attempt to get a horiz 20m+ ant on a mobile? (I haven't!) Regards, JS |
#14
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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. |
#15
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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. |
#16
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#17
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John Smith wrote:
Or, if you don't wish the built-in limitations of Eznec (the demo version), try MMANA GAL. Will feed the same data to the nec engine(s.) Regards, JS Forgot, should have given a URL to go with that: http://mmhamsoft.amateur-radio.ca/mmana/index.htm Regards, JS |
#18
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On Jul 6, 1:16 am, wrote:
Ya know what, I guess he is running as a broadside array after all.. I was thinking he had the elements horizontal, but after rereading the first post, he does have them stacked. And if they were in phase, that should be a broadside array. Sooo... I finally decided to check it in the program using two 1/2 wave elements for 10m, with the lower element at 1/2 wave up, "16 ft", and the upper one at appx 5/8 wave higher. "37 ft" Using the single lower element alone, I got 2.08 dbi. Using both in phase, I got 6.8 dbi.. So, it should work as planned.. Not sure what the problem would be though, unless you have coupling problems with other metal in the area, etc.. |
#19
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On 6 jul, 05:01, Michael wrote:
On Jul 5, 10:44 pm, "Hal Rosser" wrote: I'm not sure, but if the Lazy H has Horizontal polarity and the folks you're trying to communicate with are using Verticals, there may be quite a bit of signal loss. Since you mentioned it was for 11 meters, can we assume you're trying to communicate without using 'skip'? It is meant for skip. I typed 10 meters at the start of the message, but 11 meters in the Subject line. Old habits die hard as I started on the CB band. Hello Michael, You mentioned that even your hor. dipole blows away the Lazy H (also for good orientation). This rules out every influence because of minimum elevation angle of main beam versus ground conductivity/ permittivity. I assume that you are talking about several S-points. There must be something really wrong. The dipole close to ground will have some different impedance (then the upper). This will cause some phase error, but this should not lead to a drastic reduction of overall gain. According to your postings, the construction is OK (no twist, feeding in the middle). I also assume that you have some spacing between the 5/8 lambda long vertical line and the actual feed line (of 200ft), to avoid coupling between the two. It can be the line, or the tuner/balun. Line Losses increase and when your VSWR in the line is very high, this may increase the overall loss in your 450 Ohm feed line. If possible compare the field strength of your hor. dipole with field strength of the lazy H. Other option is to find an unused frequency en put in lots of power and look for temperature increase. Best regards, Wim PA3DJS www.tetech.nl The mail does function when you remove abc |
#20
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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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