I noticed a youtube video a while back where someone disconnected his cable wire from wall cable outlet and placed it against a screw head holding the faceplate to wall.He had the small wire in the coaxial cable touch the screw and he switched his tv setting from cable to antenna and was able to receive his local free channels in HD.Does this concept make sense or just another youtube scam?Im facing comcast scramble of all free local channels in a few weeks forcing us to get a box.I have a tv that I have been using its HD tuner to get local HD.This would be a great option but cant figure out how to secure the cable wire to the screw head.In the video he just places it against screw in such a way that wire stays put but seems that seems like a it would always slip off.
Anything metal can be used as an antenna. That does not mean it will be a good antenna. It was actually 12 years ago today (9/11) that I disconnected the cable leading to the TV in my classroom which was meant for a closed system only and shoved the center conductor of the cable into the frame around the blackboard. It got a good enough analog signal that all of the other teachers were stopping by my room and asking "how did you do that?"
You would be much better researching true indoor antennas if that is even appropriate in your locale.
First, there is no such thing as a HDTV antenna. It is a VHF antenna, just like we have been using for 60 years. If you search under DIY antenna, you will see many designs. It is very hard to beat the good old bow-tie. A commercial built antenna will have the details in impedance worked out that a DIY may not. I have built a lot of DIY antennas, Yagi, LP, Rombic, loops. They look very simple, but the little details matter. A lot of good info in from the ARRL antenna compendium. Note they do almost always give 50 Ohm designs, not the 75 you need.
How easy? OK strip about a foot of the shield off a piece of coax. Now you have a quarter wave whip. Everything else gets more complicated.
Easy there tvrgeek, you get it right by saying there is no such thing as an HD antenna, then you go saying its VHF. It's all about frequency, not carrier type. There are still VHF channels in the VHF frequency, but the many are UHF frequency with whatever virtual channel the station wants to be known as.