On 11/05/2013 09:23 AM, Dick Steffens wrote: > > I tried this one a couple of months ago: > > http://www.popularmechanics.com/technology/how-to/tv/build-your-own-digital-tv-antenna > > I didn't have the right kind of washers and the wires kept slipping out > from under the screws.
I soldered the wires together. Also, A sheet of aluminum foil as a back plane increases UHF signal strength at the expense of added directionality. But I have been a do-it-yourselfer for as long as > I can remember. I was around at the dawn of skateboarding. (This is in > the category of having to walk uphill both ways to school and back.) I > made my own skateboard out of a 1x3 board and an old skate, the kind you > put on under your street shoes. That worked well enough to get me > started, and I've followed that philosophy since then. I was still in diapers them days. You old geezer! Same here, tinkering with whatever home remodeling scraps a are left over. > >> I am 11-13 miles from PDX towers, on the Vancouver side. I can pick >> up ALL PDX channels crystal clear with this two designs: > > From tvfool it looks like I'm just under 15 miles from the towers. I > got a good signal on my simple dipole when I first tried it, but now, > not so much. I can get 23 channels, but not OPB or KGW. Optimal position is about 30 ft above ground level to avoid signal scattering. I can pick up OPB and KGW with the antenna new the ceiling (7-8 ft up). Also, I am on a bit of a ridge above the Columbia. > > Finally, a technical question: Is there something about a fractal design > that improves performance? I can see how it saves space, but does it do > a better job than the simple Vs on their sides style? > > Also, is there anything important about the 1" spacing and the 120/60 > degree bends? > > I'm guessing that what matters is that the wire is a certain length > relating to some fraction of the wavelength of the signal. For saving > space would any shape the wires took have the same effect, like a > spiral, or a squared off spiral? There's a bunch of mathematics re: fractal antenna designs. Heck, I've forgotten just about everything (brain seems to be getting full...old stuff drips out...). The 120/60deg bends are particular to the Koch (ie snowflake) fractal, other fractals will have other angles. The Koch is the easier one to make. The 1 inch has to do with the fractional wavelength, IIRC. Fractals are nice since the have a very wide frequency response over UHF and VHF. As you so to higher Koch fractal orders (more bends at 1/2 and 1/4 inch, it gets tricky. Loops won't work: these are for AM and shortwave: http://en.wikipedia.org/wiki/Loop_antenna > My wife used to do stained glass work and still has some copper foil > tape. One of those designs talked about poking the intersections of the > tape with a pin to make the connection between them since the adhesive > on the tape is not conductive. I would think that a pin hole through the > two pieces of tape would make a connection, but how long would that > last. Wouldn't it be better to solder the two pieces of tape together? Yep, you can "tin" or brush a bit o' solder over the top of the overlapping ends. Be quick so as to not melt the adhesive or substrate. I have an left over thin sheet on Lexan I am hoping to have time soon to paint on a nice 2nd or 3rd order Koch fractal for the that HDHomerun I have my eye on, for when I get around to firing up MythTV. In the meantime, I might just run coax straight to each LCD TV. _______________________________________________ PLUG mailing list [email protected] http://lists.pdxlinux.org/mailman/listinfo/plug
