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Post by homerbb on Dec 4, 2011 19:17:29 GMT -5
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Post by cbrown on Dec 5, 2011 9:24:52 GMT -5
Glad you got it up there a bit. I made a quad and just had it sitting on the roof. Never really worked well, but I wanted to get a quick antenna on the rental house roof. I do like quads, though.
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Post by homerbb on Dec 5, 2011 10:21:29 GMT -5
I wanted to see how the attic loop antenna compared to an outdoors loop.
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Post by cbrown on Dec 6, 2011 9:48:41 GMT -5
I would assume if both are made to the same specs the outdoor should be better. But I've been wrong before!  |
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Post by homerbb on Dec 6, 2011 10:39:45 GMT -5
They are not the same
The one in the attic is a rectangle, roughly 6 x 12 in dimensions.
So far, the outdoor one is better, but the rectangle, corner fed, and using twinlead feedline, is still in the contention.
In fairness, that was part of what I was trying to compare. The effects of using a longer run of RG58 coax to an outdoor antenna versus a shorter run of low loss twinlead to an attic antenna forced into a rectangle shape to avoid interaction with attic fan, duct work, wiring, etc.
I am having so much fun with DX I am having a difficult time studying the two for difference.
Reports from the other end so far puts the outdoor in front.
Coax length = 89'
300 Ohm twinlead length = 30'
twinlead is matched with a 4:1 coax balun, and a 1:1 coax choke choke at the transmitter end.
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Sandbagger
Administrator/The Boss 
Posts: 6,250 
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Post by Sandbagger on Dec 6, 2011 12:46:44 GMT -5
They are not the same The one in the attic is a rectangle, roughly 6 x 12 in dimensions. So far, the outdoor one is better, but the rectangle, corner fed, and using twinlead feedline, is still in the contention. In fairness, that was part of what I was trying to compare. The effects of using a longer run of RG58 coax to an outdoor antenna versus a shorter run of low loss twinlead to an attic antenna forced into a rectangle shape to avoid interaction with attic fan, duct work, wiring, etc. I am having so much fun with DX I am having a difficult time studying the two for difference. Reports from the other end so far puts the outdoor in front. Coax length = 89' 300 Ohm twinlead length = 30' twinlead is matched with a 4:1 coax balun, and a 1:1 coax choke choke at the transmitter end. So the attic version isn't even 1/4 wave dimensions? I would think that would be at a major disadvantage. |
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Post by Night Ranger on Dec 6, 2011 13:22:18 GMT -5
They are not the same The one in the attic is a rectangle, roughly 6 x 12 in dimensions. So far, the outdoor one is better, but the rectangle, corner fed, and using twinlead feedline, is still in the contention. In fairness, that was part of what I was trying to compare. The effects of using a longer run of RG58 coax to an outdoor antenna versus a shorter run of low loss twinlead to an attic antenna forced into a rectangle shape to avoid interaction with attic fan, duct work, wiring, etc. I am having so much fun with DX I am having a difficult time studying the two for difference. Reports from the other end so far puts the outdoor in front. Coax length = 89' 300 Ohm twinlead length = 30' twinlead is matched with a 4:1 coax balun, and a 1:1 coax choke choke at the transmitter end. So the attic version isn't even 1/4 wave dimensions? I would think that would be at a major disadvantage. I've used tall rectangle shaped full wave loops and full wave delta loops on the CB band. Both performed well. I never did a side by side comparison, but most articles I've read claim the tall rectangle configuration has the most gain. The delta loop is the easiest to put up as you can just hang it in between two trees. It looks like an upside down pyramid with insulators on the top two corners, and the feedline at the downward pointing corner. On the delta loop I used 300 ohm twin lead back to an antenna tuner with a 4:1 balun. On the tall rectangle loop I used a 1:1 voltage balun at the bottom of the antenna for horizontal polarization and then to coax. For vertical polarization I used a 4:1 voltage balun in the middle of one of the sides of the tall rectanlge full wave loop and then to coax. The SWR was around 1.3:1 for the vertical polarization. I used the plans in the ARRL handbook for the tall rectangle full wave loop dimensions. Night Ranger |
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Post by homerbb on Dec 6, 2011 13:41:40 GMT -5
That was the info I got on the rectangle shape, too - a tiny bit more gain over the square. It fits better in the attic, and while it is top and bottom (it's actually diagonal along the roof rafters) 12' and sides 6', it seems to outperform the 1/4 sided square I had up there.
I attribute this to the fact it is farther away from any reflective things in the attic, and perhaps also to the superior feedline system.
SWR 1.05:1 on both ch 40 and ch 1.
I find it something of a paradox as the best configuraton should be tha loop that has the greatest area within the loop.
square = 81 sq ft
rectangle = 72 sq ft
circle = 103 sq ft
delta = 62.5 sq ft
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Sandbagger
Administrator/The Boss
Posts: 6,250
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Post by Sandbagger on Dec 6, 2011 18:04:52 GMT -5
That was the info I got on the rectangle shape, too - a tiny bit more gain over the square. It fits better in the attic, and while it is top and bottom (it's actually diagonal along the roof rafters) 12' and sides 6', it seems to outperform the 1/4 sided square I had up there. I attribute this to the fact it is farther away from any reflective things in the attic, and perhaps also to the superior feedline system. SWR 1.05:1 on both ch 40 and ch 1. I find it something of a paradox as the best configuraton should be tha loop that has the greatest area within the loop. square = 81 sq ft rectangle = 72 sq ft circle = 103 sq ft delta = 62.5 sq ft Oh, that's more like it. In your last post you cited 6 and 12 "in" (inches?) for dimensions and I thought that would be better off on 2 meters, or at a greatly reduced efficiency on 11 meters. |
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Post by homerbb on Dec 6, 2011 18:17:27 GMT -5
Oops I must've had shift lock on.  |
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Post by homerbb on Dec 7, 2011 13:15:11 GMT -5
Some have said it's hard to tell whether the loop is mounted vertical or horizontal. I hope this helps:  Some things are so lovely it almost makes you cry . . . |
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Post by homerbb on Dec 15, 2011 22:45:16 GMT -5
I mounted the loop vertically a few days ago, and today I constructed a reflector and put it on the boom with the driver. Tomorrow I hope to finish it and see how it does. After that we'll see about perhaps making it dual polarity. . .
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Post by cbrown on Dec 16, 2011 10:28:00 GMT -5
A quad beam, very nice! What type of director did you use?
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Post by homerbb on Dec 16, 2011 19:27:17 GMT -5
A quad beam, very nice! What type of director did you use? No director. It's a 2 el Dri/Ref.  |
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Post by cbrown on Dec 20, 2011 9:37:40 GMT -5
Well, it still looks darn good! Do you have a rotator on it?
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Post by homerbb on Dec 20, 2011 11:49:04 GMT -5
Not yet. I have a light one I need to clean up and check out. That's one of two reasons I haven't expanded this thing to more than two elements.
1. rotator too small
2 tower too light for now.
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Post by cbrown on Dec 21, 2011 11:02:57 GMT -5
Okay, I have to ask: How many elements are you thinking of expanding to?  I think even a light Radio Shack rotator should handle 4 elements with your design. |
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Post by homerbb on Dec 21, 2011 17:41:32 GMT -5
I am looking at the possibility of 3 elements, although this 2 element is delivering some excellent results.
It is a Radio Shack TV rotator I have, but I need to clean it up and see if it will act properly.
I have what I need to add a director, but weather is very unpredictable3 right now.
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Post by homerbb on Dec 22, 2011 0:09:36 GMT -5
Cleaned up a little more today.  |
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Post by cbrown on Dec 22, 2011 10:40:33 GMT -5
Ah, I was guessing around 10 elements. Still looks great!
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Post by homerbb on Dec 23, 2011 22:15:47 GMT -5
It's up at 37' to the boom, now. With the 80" spacing on the new aluminum boom, it seems to have smaller beamwidth than it did with spacing at 75", the last spacing.  |
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Post by cbrown on Dec 29, 2011 11:20:20 GMT -5
How so?
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Post by homerbb on Dec 30, 2011 20:51:32 GMT -5
I notice that I have to be more directly pointed toward the stations I want to work than before.
If I point SW everything in the MW is way down, whereas before it ws no so much so. It isn't real narrow, just more so than before.
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Post by cbrown on Jan 2, 2012 9:53:08 GMT -5
So you are getting a tighter, more discreet beam width? Did your signal increase to stations in the direction it is pointed?
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