Coat hanger HD antenna, what wire?

vbimport

#1

There are designs all over the internet for coat hanger antennas that claim to work better than many expensive indoor antennas. So I have a few expensive indoor ones and like many, I am dissatisfied. there are many plans that use these same dimensions.


I’m building that without the backboard and aluminum foil (I can always add it on later ans many of the other plans don’t have it).

So I decided to use 12ga solid coper wire instead of a coat hanger (I have stranded 14ga wire for the connecting pieces that go down the center). The issue is that the wire is insulated (not shielded, just electrically insulated). Will the insulation block the signal at all. Should I strip it all off? Am I right that the copper wire would probably work a little better than coat hanger?

Also, I have a transformer that is labeled as 75ohm. Is that going to be suitable for hdtv? If not, I might have another one laying around (I’ll have to hunt for it though).

Any help would be appreciated.


#2

Hi ripit me again…antennas can be homemade. That said you need to find out what the length needs to be. Wave lengths are different. I have no idea what the length needs to be sorry.

As long as your not transmitting on it the no worries about standing waves.

I used to use a coat hanger for a tube type CB radio years ago but i would not recommend it. With transmitters the length needs to match very close. So with TV i’d say you can get close and get away with it.

I would use bare solid copper wire.

That guy doesn’t mention what the load is on that coil :\


#3

The plans give very exact dimensions (and there are several sites that use these same dimensions). Each arm is a v that is 7 inches long and 3 inches apart at the end. there are 4 sets of v’s that are 5 3/4 inch apart. The only bare copper lowes had in stock was pretty big (like 8ga) and would have cost 15-20$. I got 12ga for about 2$ but it was not available bare.

So it would help to strip off all the wire insulation?


#4

Well if you think about it antennas are aluminum and they are bare. I think the insulation would hamper the incoming signal somewhat. It doesn’t really matter on the gauge of the wire but just so it’s stiff enough to hold the shaped you make it.

You could try it with the insulation on but if you get bad signal strength then you would have to take it apart and strip it off so up to you i guess.

I would strip it off but that’s me.

Edit:
Also i would use the same ohm coil (transformer) as the lead coax. Look at the back of the TV and see if it gives you a clue or look in the manual.


#5

I’m just going off blind memory but I had thought 75 ohm was for uhf and 75 ohm was for vhf, so where does Digital fall? If it works, I’m hoping to use a cheap rca distribution amp to send it all over the house. Its a cheapo one like this but 4 channel.
http://www.thetwistergroup.com/store/customer/product.php?productid=VH100%20D37394&source=fr
I’m gambling on a lot of things here but I’m using stuff I already have so I’m out about 3$ for the wire. Will the 75 ohm one work with digital (I think it resides around vhf channel 6 but I could be way off).

On a side not, all my tv’s are sd, but I have all of them and all my computers enabled to receive digitalsd/hd and convert as necessary (I dont have all the bugs worked out on the computers but they work).


#6

I really don’t know ripit and i wish a buddy of mine was a member here cause he knows all that stuff. The uhf (ultra high) and vhf (very high) anyway.

Like i said i don’t see any mention of the coil ohms or the coax ohms he used?

I just looked at my Sat receiver and Dish uses 75 ohm for whatever that’s worth.

Usually an antenna is made to be right in the middle of the band. So when you are above or below it still works but looses at high and low ends of the band.


#7

In the back of my mind, I know stripping off the shielding might help and it wont hurt, but this is household wiring (it’s some multi layer crap that is hard to strip). I have started stripping the cut and bent pieces, and its a chore (I just want to get done before the wife gets back with the kids). I was hoping someone might know from experience or education, if it would hurt…


#8

[QUOTE=ripit;2057024]In the back of my mind, I know stripping off the shielding might help and it wont hurt, but this is household wiring (it’s some multi layer crap that is hard to strip). I have started stripping the cut and bent pieces, and its a chore (I just want to get done before the wife gets back with the kids). I was hoping someone might know from experience or education, if it would hurt…[/QUOTE]:\ if it’s that thick…lol i don’t know man. lemme call this guy real quick. brb


#9

Its not that thick, its just multi layer. the outside is a clear plastic layer (thin but the hardest to cut through). There seems to be a dual layer under it that may be two types of plastic. I don’t have anything that sharp in my toolbox, and I have good kitchen knives (US made Chicago cutlery) but I haven’t kept up on sharpening them. As luck would have it, I have a couple of kitchen aid knives I just bought that seem to be sharp enough to slit the insulation… The bad thing is, now its will be duller, and I’m pretty bad about sharpening my knives… Wish me luck!!!


#10

Fyi, on a side note, on the insulation, most wire has basic easily shippable single layer plastic. I tore a 40 wire ide cable apart the other day for wire (I needed fine wire and what the hell am I going to do with a 40 wire ide cable), and I stripped 1/2 inch of the ends of the wire with my fingernails. Granted its fine wire, but the insulation cuts and or pulls apart reasonably easy without excessive elasticity. This stuff won’t cut easy (you have to have a very sharp tool), and will not pull off (the outer layer will stretch forever if not completely cut and caused the inner layers to stretch). I did get it all off though. Its no match for a sharp knife, but its gotta be very razor sharp. A utility knife is not sharp enough.


#11

ahh he mentioned a few things…sorry so long. He’s not familiar with the wave length for what your needing. Said 75 ohms would be good for both transformer and coax. Said yeah would be best to strip the insulation off. Also if it’s that hard to get off to burn it off. We live in the country though so not sure if you can have an outdoor fire or not.

Also i sent him the link to that antenna build.


#12

Been easier coat hangers i guess. Then all you would have to do is strip it where the bend is. I still think copper would be better.


#13

I did manage to get the insulation off (good to know that it might help since I went to the trouble). One of my nice sharp kitchen knives isn’t so sharp anymore. I appreciate the help. If the transformer is good for digital, then I’m set. The problem isn’t installing a new transformer, or finding the other one I have, or even buying one (they are cheap), but its being build now, and since it wont fit on the entertainment center, (about 24 inches clearance to the ceiling and I need at least 30 inches with the rotator) its got to go behind it. thats nice because while I would put an ugly monstrosity on top, the wife wouldn’t like it. there is plenty of room back there, but it has been intentionally blocked off with very limited access, to keep the kids out. Thats where I put computers when I am working on them for other people, but it takes 15 minutes moving stuff to get back there…


#14

Hey if it works and you have $2 in it…what the heck you know…

You can make another at a later date.


#15

Sorry so many posts but not sure if you see my edits:

He also suggested building a quad. Said it would be really small. Use 50 ohm coax on it. Doesn’t matter if you hook up the shield or center of the coax to it (both need to be hooked to it) and you won’t need a transformer. But then again he needs to know what band HDTV runs on…mhz or whatever wise.


#16

@ ripit,

For your “Coat Hager Bowties” suggest visiting a Welding Supply Shop and purchase Brass Brazing rod. When visiting the Welding Supply Shop ask for 36-inch long 1/8-inch diameter Brass Brazing rods to make your “Coat Hager Bowties”. Brass is an excellent electrical conductor and the 1/8-inch diameter Brass Brazing rod will work much better than your Lowe’s 12 gauge copper wire or Coat Hangers.

Also for your 30 inch by 16-inch Aluminum Foil covered “Reflector Board” suggest visiting a Metal Shop that manufactures copper Gutters and Downspouts and ask for a 30-inch by 16 inch copper sheet that they use in manufacturing their Gutters and Downspouts. The copper sheet will reflect electrical signal many times better that Aluminum Foil wrapped around a piece of plywood and/or cardboard.

Regards,
bjkg


#17

@Bob, iprobably didn’t see your edits, I started posting a hour before the family left, but I have been working on it while I posted (so I didn’t reread) and might have missed something.

A Quad??? How do I do that (not sure what one is). I’m indoors but have a few spots where there is libral space for an antena, and I have a remote rotator).

@bjkg, yea I have welded before (I have a degree in gunsmithing), and thats a great idea. If this design works, going to a heaver rod (and something stiffer than soft coper like I am using) might be much better. I got the arms as straight as I could, but copper is too soft to get it nice and straight. maybe revision 2 would work with that (I like building things).

About the reflective backboard? I just kind of guessed that it was to block background signals. I am not going to do it now (it should be easy to add later when I have more time for a project). I just didn’t have parts handy for even the tin foil one (short on screws in my screw kits, and smaller wood). Is that what it is for? If so, would aluminum work (copper is usually expensive and this is a budget experiment as my wife works at a house builder, and is all but layed off, Us recession and reinstate market and all).


#18

[QUOTE=bjkg;2057059]@ ripit,

For your “Coat Hager Bowties” suggest visiting a Welding Supply Shop and purchase Brass Brazing rod. When visiting the Welding Supply Shop ask for 36-inch long 1/8-inch diameter Brass Brazing rods to make your “Coat Hager Bowties”. Brass is an excellent electrical conductor and the 1/8-inch diameter Brass Brazing rod will work much better than your Lowe’s 12 gauge copper wire or Coat Hangers.

Also for your 30 inch by 16-inch Aluminum Foil covered “Reflector Board” suggest visiting a Metal Shop that manufactures copper Gutters and Downspouts and ask for a 30-inch by 16 inch copper sheet that they use in manufacturing their Gutters and Downspouts. The copper sheet will reflect electrical signal many times better that Aluminum Foil wrapped around a piece of plywood and/or cardboard.

Regards,
bjkg[/QUOTE]bjkg you know what band HDTV transmits on by chance?


#19

[QUOTE=ripit;2057066]A Quad??? How do I do that (not sure what one is). I’m indoors but have a few spots where there is libral space for an antena, and I have a remote rotator). [/QUOTE]Quad antennas > http://en.wikipedia.org/wiki/Quad_antenna i’m not sure which he’s thinking about so until he knows what band HDTV transmits on he can work up some specs on the size it needs to be.

First fast builds are always like a prototype so if you like building then you can get it perfected.

The reflector board makes it directional hence the need for a rotor to turn it for signal strength.

I hear you on the jobs…US recession thang :iagree: Might be more people wanting to go this route than you would think. But one needs to be in a big city where there are many TV stations.

Plus i’m kind of interested now :bigsmile:

Edit:
After reading bjkg’s suggestions…you don’t want to get it to heavy…use light weight materials.

Any HAMS here and would like to add?


#20

I like prototypes, and rebuilding to improve, however I would like at least a somewhat working model on the first try, as I have very little free time anymore (young children). there is no telling the next time I will have any free time to improve it (its amazing I got this far). The wife is even making a lat night trip to wallmart with the kids for groceries so I can finish.

I am in a big city (wouldn’t have it any other way). I’m in Irving which is a suburb of Dallas (a few miles from DFW airport). I actually got a rotator that I plan on using with it at circuit city for 16$, originally a 60-80$ phillips model. the reviews are horrible in that weather destroys them, but I plan on using it indoor. Its the first rotator I have ever owned (always lived in apartments), but I think I can get it to work and fit behind the entertainment center (I have a somewhat large wall size entertainment center that cuts the corner of a room, so there is a large space back there).

I used to have time and did building projects like this a lot more, but now they hae to be functional ones (still don’t have time often), but tv/video/content on my htpc is all I can afford till the kids get out of daycare.