Mine is just a copper wire, no fancy cardboard tubes or coils.
How I made an HDTV antenna so I could watch Jeopardy last night
31–40 of 74 posts
Re: How I made an HDTV antenna so I could watch Jeopardy last night
#32Thanks, 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 ca…
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 ha…
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)
Re: How I made an HDTV antenna so I could watch Jeopardy last night
#33Why doesn't the outside part of the coax port have to also touch the wire?
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)
Re: How I made an HDTV antenna so I could watch Jeopardy last night
#34Heres plans for an antenna I built. http://www.tvantennaplans.com/ I like the simplicity and potential of your design though. I want to try an array of tubes and wiring, and see how well that works.
Google Chrome is warning me that soccergoalplans.com is including content from an external website known for malware.
Re: How I made an HDTV antenna so I could watch Jeopardy last night
#35Thanks, 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 ca…
The current running down the wire produces an electromagnetic field in a circular pattern around the cable. When current also travels the opposite direction it creates the same field in the exact opposite direction to cancel it out. That is essentially how shielding works in coaxial cables. The outer sheath is just a continuation of the wire traveling in the opposite direction.
Re: How I made an HDTV antenna so I could watch Jeopardy last night
#36Earlier quoted context omitted.
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.
Nah, it's to ground the shield. Shields work marginally better when grounded, but the difference is minor.
The shield shouldn't work at all unless it is grounded.
Re: How I made an HDTV antenna so I could watch Jeopardy last night
#37Gray Hoverman antennae do a good job for longer distances: http://www.digitalhome.ca/ota/superantenna/
If you search a little more through the http://www.digitalhome.ca/ forums, you can find newer generations of the design. Various folks have been using genetic algorithms to find more efficient modifications to the original design. http://www.digitalhome.ca/forum/showthread.php?t=119489
Re: How I made an HDTV antenna so I could watch Jeopardy last night
#38This 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.
Re: How I made an HDTV antenna so I could watch Jeopardy last night
#39Ive been looking for an excuse to do this:
http://www.re-nest.com/re-nest/how-to/how-to-make-a-string-t...
Thanks!
Re: How I made an HDTV antenna so I could watch Jeopardy last night
#40Earlier quoted context omitted.
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.