Thanks, I'm glad you took our comments to heart :)
Two questions:
1. What exactly is the purpose of the cardboard tube? I'm guessing the key point is that it's non-conductive, but would the same coil work without the cardboard? (not very knowledgable about antennae I admit)
2. How the hell does that connector even work? It looks so marvelously out of place ... does this mean the wire mesh around the normal coaxial cables is just shielding and doesn't actually do anything? If so, how come you don't need shielding?
Those were the two main questions that popped to mind, obviously I don't know anything about this stuff and I could probably look it up somewhere. But maybe someone here can provide a human-to-human good enough explanation.
Shielding is useful but not exactly required if the signal is strong enough and the cable is short enough. EX: You can use barbed wire to send 10 baseT. However, 1 gigabit has major issues without shielding.
PS: I once noticed my Sega genesis was producing a vary fuzzy picture, so I went to fiddle with the cable and noticed it was not even plugged in. At the time I really freaked out and to this day I still wish I had a picture.
I went to fiddle with the cable and noticed it was not even plugged in.
Back in college, we were watching a, umm, adult video on my roommate's VCR. The guy from the room next door walked past, and said "oh, you're watching the movie too?". It turns out that we'd mistakenly connected the VCR's RF output to the antenna, so the guy next door was watching our transmitted movie. (although his picture was poor)
The shell of coax (and what's in the space between it and the center conductor) also affects the impedance of the cable or antenna system. It's generally not that critical for a receiving antenna.
Sticking up almost any wire more than a few wavelengths long will collect a reasonable amount of a strong signal. A truly resonant antenna for the frequency you're interested is a lot better, but not that helpful for general HDTV viewing where the frequencies range all over VHF and UHF.
One of the amazing things I've learned from years of ham radio is how many unseen and unpredictable things affect radio signals. You can move your antenna twelve inches to the left and lose a signal completely, especially inside a structure. Or an airplane flying overhead can reflect enough "multipath" signal to wreck your TV viewing for 30 seconds. Of course your own body blocks a lot of signal and is capacitively coupled to the antenna system as you adjust it. So if you're playing with an HDTV antenna and are too young to remember the fun of constantly adjusting TV rabbit ears, just keep tweaking until you get a good signal.
"...too young to remember the fun of constantly adjusting TV rabbit ears..."
Too young, ha! I use rabbit ears on my HDTV (no cable, just netflix + locals is enough for me) and laugh when I go to Best Buy and see "state of the art high definition" antennas for anywhere from $20 to $100. The same laugh hits me when I go down the gold plated monster cable isle, but that's a different story.
I used to think Monster cables were a complete joke too until a musician friend pointed out that they have a lifetime warranty and very generous terms of exchange. One can essentially walk into any music store in the country and swap out the splinched cables for new ones, no questions asked.
It's an interesting pricing model, and the $20-$60 cables more than paid for themselves after a single tour. Probably not appropriate for casual use though.
A place not to do this is with R/C helicopters. Best to buy them from Brookstone with the 1-year no-questions-asked warranty -- you WILL destroy them and you can go through your 3-6 choppers for the price of one.
Nice tip. I've always wanted to get one of the R/C helicopters and was always planning on getting it from one of the aisle mall shops - but this advice is helpful.
What you said may be true, but their main justification for the cost is the supposed supreme quality over cheaper cables that has been disproven time and again, and some of their cables cost much much more than $60. That's not to mention their litigation practices. They are truly a horrible company.
I used to think Monster cables were a complete joke too until a musician friend pointed out that they have a lifetime warranty and very generous terms of exchange. One can essentially walk into any music store in the country and swap out the splinched cables for new ones, no questions asked.
Is he doing it right? Should the cables fail after every show? Shouldn't he just get better cables?
1. Basically, I just wanted something I could wind a length of wire around and stick in my window. The tube did the trick. After the show, I tried a few other things, like wrapping the tube with tinfoil, but the basic wire around the tube design performed best.
2. The shielding is there to keep signal interference out, which is useful if you have a clean source to start with (ie: Cable TV or a properly designed antenna). In my case, I just wanted to pick up as much signal as possible, and this is what I had to work with.
very Interesting attempt. I would like to give a try.
Btw, did u do some math in arriving at length of cable or the number of winds? Did u try increasing number of winds etc?
1. Structure. The wire he's using isn't strong enough to just stay up standing by itself. It would fold over on itself. Also, it probably does need to be non conductive or you need to use coated wire.
2. It's not shielded because the entire thing is the antenna. I guess he could shield it between the TV and the actual wrapped tube part but this is sow low-tech it wouldn't make a difference. Your standard roof mounted antenna is shielded between the antenna and the tv because you don't want interference between the two points.
>Your standard roof mounted antenna is shielded between the antenna and the tv because you don't want interference between the two points.
To clarify this, with a roof mounted antenna the wire needs shielding because it is typically running down the middle of the house and thus would be subject to interference from the many electronic devices therein.
With this guy's solution, the wire just runs out of his window, and therefore as long as he doesn't have any ageing analogue equipment (speakers, cordless phones etc) near his TV or his window the issue of interference is minimal.
My HDTV antenna is a paperclip stuck into the back of a TiVo. I get solid HD reception, no artifacts or other problems. It is all about how close you are to the broadcast towers. I have line of sight to towers that are about 12 miles away.
Go to tvfool.com and put in your addresses. From what I can find they have Canada data in their DB too. The first step to understand how to get good reception is to learn where all the towers are located and what band they broadcast on.
You can use http://www.tvfool.com/ to chart the strength of nearby TV signals based on your location. It includes both US and Canadian broadcast towers.
I'd be interested to know the strength of the signals you're able to receive with your paper-towel-tube antenna design.
Using your antenna, how could I go about amplifying the reach in an attempt to pick up more channels and/or increase the display quality of current channels?
Going through common antenna design compromises...
Depends on your location, of course, but the most effective thing I could do is get out of this valley. Next, I'd straighten the antenna wire and move the antenna outdoors (with a 75Ω coax line connecting it to the TV). You could also adjust the length so it's resonant at a particular frequency, but that will weaken the signal you receive on other channels. Alternatively, cutting it way longer than the minimum resonant length (like an order of magnitude or so) seems to make for a pretty forgiving frequency response. Then again, commercial broadcast transmitters are probably running enough output power that unobstructed line of sight makes more of a difference than anything else can.
I got the same plans via Make and have been using mine for 2+ years. It works awesome. Before dtv I could get 1-2 stations of mostly fuzz. Now I get 7 channels in full HD.
same here... I receive over 30+ channels now, most are HD (LA) area. With this and a computer hooked up to my TV would never consider going back to cable.
I was looking at that design yesterday. I decided I didn't have the time to buy the materials and build it in the 30 minutes I had before the game started, so I ended up watching on Youtube. I plan on building this antenna in the future though.
Does this work in the US? I've been under the assumption that with the recent switch from analog to digital signal (and the need for a digital converter box), connecting an antenna straight to a TV no longer works.
The frequencies are the same, and since they're not doing anything freaky with the signal (just broadcast) the same kind of antenna ought to work. In fact, you should get a better signal, because ATSC has much better multipath resistance than NTSC did.
This article is excellent! And thank you, chaosmachine, for providing instructions for replication.
It's my strong opinion that everything here is ethically sound. This sort of "hacker" culture is the meat and potatoes of what drives innovation in the United States today, and whether this specific incident results in a new product or simply higher security by cable providers, progress has been made.
What do cable providers have anything to do with this?
He built his own antenna to receive local channels that are broadcast over the air. These are broadcast specifically so that people with antennas can receive them.
Because no signal is transmitted on the outside part, that is just used to secure the cable to the port. If you look at a coax cable, you will see it is essentially a copper wire wrapped in shielding wrapped in a vinyl(?) casing and the end is terminated with a connector that feeds the copper into the port and secures the connection.
I think that DirecTV setups transmit power and control signal through the shield. A given wavelength carries two polarized signals and the control signal tells the LNB which polarization to watch for. (or maybe I've got it all wrong, but this is what I've gathered from setting up and troubleshooting my own)
You are right, though satellite transponder frequencies with different polarizations do not typically share the same wavelength. With alternating polarization they are offset by (presumably) half the frequency separation needed for identically polarized signals.
I don't think coaxs have a 'return' on the actual cable. The outside part of a coax is just a screw for holding the cable in place. It could be made with plastic for all it matters.
Nathan Cohen made this discovery after listening to a Mandelbrot talk on fractals: http://en.wikipedia.org/wiki/Fractal_antenna#Fractal_element...