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Author Topic: Effects of modification to gutter antenna  (Read 3410 times)

Offline radiozed

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Effects of modification to gutter antenna
« on: July 02, 2016, 1717 UTC »
Question for the experts here as I don't have access to antenna modeling software (nor would I know how to use it).  I'm currently broadcasting off an approximately 40' long aluminum gutter mounted about 25' up on the side of my house.  One end points due north and one end points due south.  Coax is connected via 25' high aluminum downspout.  Coax shielding connected to about a 40' long counterpoise stretched across the back yard.  Whether this setup behaves more like an inverted L, or a dipole, or simply a vertical...I'm not really sure. 

In any case, my reception reports seem to be mostly directional to the east of me, with some reports to the north (but it's a pretty close station).  On the north side of my house I also have an aluminum gutter that's about 30' in length.  I've been thinking of getting up on the roof and running a wire from the north/south gutter to a connection on the east/west gutter.  Mostly as an experiment, but also just to see if it makes my signal a little more omni-directional.  For you folks who understand antennas far better than I do...any idea whether this modification would do anything for me?

Offline moof

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Re: Effects of modification to gutter antenna
« Reply #1 on: July 02, 2016, 1939 UTC »
Jeez who knows what will happen with a gutter antenna?  Kind of like random bed springs antenna. Maybe something bad maybe something good. https://vimeo.com/126720159
I'd recommend a basic dipole, even with thick magnet wire if stealth is needed.  Can run up to 100 watts into the thick red magnet wire stuff.  Larger wire if stealth not needed.  I got the signal out well over most of US with NS oriented thin magnet wire anywhere from 5-50 watts.  Sun willing and shit.

Offline EliteData

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Re: Effects of modification to gutter antenna
« Reply #2 on: July 02, 2016, 2046 UTC »
Question for the experts here as I don't have access to antenna modeling software (nor would I know how to use it).  I'm currently broadcasting off an approximately 40' long aluminum gutter mounted about 25' up on the side of my house.  One end points due north and one end points due south.  Coax is connected via 25' high aluminum downspout.  Coax shielding connected to about a 40' long counterpoise stretched across the back yard.  Whether this setup behaves more like an inverted L, or a dipole, or simply a vertical...I'm not really sure.  

In any case, my reception reports seem to be mostly directional to the east of me, with some reports to the north (but it's a pretty close station).  On the north side of my house I also have an aluminum gutter that's about 30' in length.  I've been thinking of getting up on the roof and running a wire from the north/south gutter to a connection on the east/west gutter.  Mostly as an experiment, but also just to see if it makes my signal a little more omni-directional.  For you folks who understand antennas far better than I do...any idea whether this modification would do anything for me?
am i to understand that you are using the rain gutter that is horizontally mounted alongside the edge of a roof as the antenna or is it something different, like you are just using the actual gutters themselves on a separate mounted platform or held up in the air as the antenna ? (im trying to visualize this)
i would also vote for moof's suggestion, a basic dipole, center fed 12GA copper wire, each side cut at about 35.5 feet for 1/4 wavelength 6.925Mhz, with a 1:1 RF current choke rated 25% above your average output power placed at the center feed point using RG8X coax as the feed cable run from the TX and an antenna tuner to fine tune any mis-matches (because SWR will never be perfect on a narrow band dipole)
here is a simple calculator you can use to get wire lengths for a dipole antenna http://www.onlineconversion.com/frequency_wavelength.htm
« Last Edit: July 02, 2016, 2058 UTC by EliteData »

Offline radiogaga

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Re: Effects of modification to gutter antenna
« Reply #3 on: July 02, 2016, 2300 UTC »
Hey Zed,
I had the same set up for antenna altho I had about 80 feet horizontal. The vertical component added about 2S units of noise.I was also concerned about the rusty screws at gutter connections.

I prefer the inverted V as moof suggested.

rgg

Offline radiozed

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Re: Effects of modification to gutter antenna
« Reply #4 on: July 03, 2016, 0049 UTC »
Question for the experts here as I don't have access to antenna modeling software (nor would I know how to use it).  I'm currently broadcasting off an approximately 40' long aluminum gutter mounted about 25' up on the side of my house.  One end points due north and one end points due south.  Coax is connected via 25' high aluminum downspout.  Coax shielding connected to about a 40' long counterpoise stretched across the back yard.  Whether this setup behaves more like an inverted L, or a dipole, or simply a vertical...I'm not really sure.  

In any case, my reception reports seem to be mostly directional to the east of me, with some reports to the north (but it's a pretty close station).  On the north side of my house I also have an aluminum gutter that's about 30' in length.  I've been thinking of getting up on the roof and running a wire from the north/south gutter to a connection on the east/west gutter.  Mostly as an experiment, but also just to see if it makes my signal a little more omni-directional.  For you folks who understand antennas far better than I do...any idea whether this modification would do anything for me?

Yes, the 40' section I'm currently connected to and the 30' section I'm proposing to connect to are both horizontal and 25' up on the side of the house. 
am i to understand that you are using the rain gutter that is horizontally mounted alongside the edge of a roof as the antenna or is it something different, like you are just using the actual gutters themselves on a separate mounted platform or held up in the air as the antenna ? (im trying to visualize this)
i would also vote for moof's suggestion, a basic dipole, center fed 12GA copper wire, each side cut at about 35.5 feet for 1/4 wavelength 6.925Mhz, with a 1:1 RF current choke rated 25% above your average output power placed at the center feed point using RG8X coax as the feed cable run from the TX and an antenna tuner to fine tune any mis-matches (because SWR will never be perfect on a narrow band dipole)
here is a simple calculator you can use to get wire lengths for a dipole antenna http://www.onlineconversion.com/frequency_wavelength.htm


Offline radiozed

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Re: Effects of modification to gutter antenna
« Reply #5 on: July 03, 2016, 0050 UTC »
Jeez who knows what will happen with a gutter antenna?  Kind of like random bed springs antenna. Maybe something bad maybe something good. https://vimeo.com/126720159
I'd recommend a basic dipole, even with thick magnet wire if stealth is needed.  Can run up to 100 watts into the thick red magnet wire stuff.  Larger wire if stealth not needed.  I got the signal out well over most of US with NS oriented thin magnet wire anywhere from 5-50 watts.  Sun willing and shit.

Currently I've managed to run 500 watts in to the gutter antenna and haven't burned the house down.  Did put up the garage door a few times.  :D

Offline Josh

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Re: Effects of modification to gutter antenna
« Reply #6 on: July 03, 2016, 1553 UTC »
You can certainly try and see how things go, even making a loop out the the gutters/wire. Some of the issues presented are just where your likely listenership is, if there's not much but farmland in certain directions you might not get many rx reports from them. Also, at 25 ft up you can expect nvis propagation on the 6.9xx band, wich means coverage from down the block to about 600 miles or so, the plus side is no gaps.
Conveniently located near Vincennes Indiana.

Offline radiozed

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Re: Effects of modification to gutter antenna
« Reply #7 on: July 03, 2016, 1958 UTC »
You can certainly try and see how things go, even making a loop out the the gutters/wire. Some of the issues presented are just where your likely listenership is, if there's not much but farmland in certain directions you might not get many rx reports from them. Also, at 25 ft up you can expect nvis propagation on the 6.9xx band, wich means coverage from down the block to about 600 miles or so, the plus side is no gaps.

I know it doesn't seem like it should work very well, but I've managed to hit even Western Europe on a good night.  I like the idea of a proper dipole, as others have recommended, but I need to keep very stealth.  The HOA cops are probably the biggest problem.  I've got no trees to string anything up to, and even if I did somebody would notice it almost immediately the way everyone's houses are stacked on top of each other.  The thing I like about the gutter is as far as any Nosy Nellies are concerned, it's just a gutter.   ;D

Offline EliteData

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Re: Effects of modification to gutter antenna
« Reply #8 on: July 03, 2016, 2154 UTC »
You can certainly try and see how things go, even making a loop out the the gutters/wire. Some of the issues presented are just where your likely listenership is, if there's not much but farmland in certain directions you might not get many rx reports from them. Also, at 25 ft up you can expect nvis propagation on the 6.9xx band, wich means coverage from down the block to about 600 miles or so, the plus side is no gaps.

I know it doesn't seem like it should work very well, but I've managed to hit even Western Europe on a good night.  I like the idea of a proper dipole, as others have recommended, but I need to keep very stealth.  The HOA cops are probably the biggest problem.  I've got no trees to string anything up to, and even if I did somebody would notice it almost immediately the way everyone's houses are stacked on top of each other.  The thing I like about the gutter is as far as any Nosy Nellies are concerned, it's just a gutter.   ;D
understood but the thing of it is this and please dont take this the wrong way, while i do not know if there are nearby neighbors and whether their electronic devices are affected or not by any spurious emissions that may be emanating from your TX setup and not knowing the dBmV and frequency of those spurious emissions, i would still have some concern especially if your own electronic devices are affected (your garage door opening/closing), you could reasonably assume that some of the electronic devices of anyone that is nearby, may indeed be affected just as well as yours, and that is something i would use caution about, because its not so much that broadcasting on SW that may get you in trouble, its the interference that it may cause that will get you into trouble.
even though you would be TX'ing after "business" hours, there still remains the chance and possibility of being discovered (an ARO possibly residing in the community).
just my two cents of advice.

Offline redhat

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Re: Effects of modification to gutter antenna
« Reply #9 on: July 03, 2016, 2216 UTC »
I second Elite's comments.  I would highly discourage operating in such situations.  HOA 'subjects' tend to be more Nazi-like and if your screw up their enjoyment of sex in the city, your going to hear about it.  I imagine this is why FM pirates get busted a lot, most of them are in residential areas running big power.

My best advice is find a friend out in the country that will let you use their barn or back lot and go portable.  You won't get in as many shows a year, but your chances of getting busted are far far less.  Plus with fewer things in the way building wise, you may get better reports.

+-RH
« Last Edit: July 03, 2016, 2218 UTC by redhat »
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Please send QSL's and reception reports to xfmshortwave [at] gmail [d0t] com

Offline radiozed

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Re: Effects of modification to gutter antenna
« Reply #10 on: July 04, 2016, 0023 UTC »
I second Elite's comments.  I would highly discourage operating in such situations.  HOA 'subjects' tend to be more Nazi-like and if your screw up their enjoyment of sex in the city, your going to hear about it.  I imagine this is why FM pirates get busted a lot, most of them are in residential areas running big power.

My best advice is find a friend out in the country that will let you use their barn or back lot and go portable.  You won't get in as many shows a year, but your chances of getting busted are far far less.  Plus with fewer things in the way building wise, you may get better reports.

+-RH

Well, I do have a proper 20' retractable vertical whip that is also pretty stealth as well.  Maybe I'll play around with that some more if it'll minimize any issues.  The main reason I don't use it more is that it gets out about half as far as the gutter antenna. 

Offline redhat

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Re: Effects of modification to gutter antenna
« Reply #11 on: July 04, 2016, 0356 UTC »
I still do not recommend operating in a residential area, particularly in this 'zero lot line' era with houses stacked upon each other.  The risk of causing problems for other and getting the knock is just too great.

Do as you wish, but be extremely careful.

+-RH
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Offline ka1iic

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Re: Effects of modification to gutter antenna
« Reply #12 on: July 08, 2016, 1440 UTC »
Hmmm... aluminum...  possible aluminum oxide on each joint = rectification = angry neighbors as the others have stated.

Hell, toss a dipole on the edge of the roof (or the top even) and call it an ice melter if you live in an area that has ice in the winter.

But I would put it on the peak of the roof... but that's just me. ::)

Did you know that aluminum filings and iron filing and (XXXXXXcensoredXXXXXX) are the makings for a great Termite b--o--m--b?  Very powerful and hot as all get out.

When you are running power to the rain gutter notice (carefully) if the aluminum oxide at the joints is glowing? If so... stop transmitting immediately...!

If you go to the peak of the roof method you may get some directionality by make a semi-inverted Vee running the antenna center at the peak and the 'legs' from the lower point of the rafters.

Always have the feed point at the highest point possible.

ie:
         roof edge (outer edge of rafter)
          _ _ _ _ 
          \
            \ antenna
           - - - ridge pole (peak of roof)
               \ antenna
          _ _ _\
          other roof edge (outer edge of rafter)  Do bass ackwards if directional (see below)

If you go this route try to get wire that has a plastic insulation with a similar color of the roof shingles.  And the coax... well hide it the best you can or find some soft plastic tubing to match the shingles (might be expensive <sigh>).

I don't know what wave pattern this might give you... a true inverted Vee is pretty most like a vertical in its wave pattern.

Anyway have fun.

PS.  I have wires every where...  why?  My morning Glory flowers need them to climb on... in the winter no one even notices  ;D
73 Vince
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