More HD experiments

Friday, July 18, 2008

Living with an electrical engineer is always…interesting. I’m also an engineer, but my desire to tinker is more software-oriented than hardware, whereas Damir likes to build things. After our initial experiments with the HD TV antenna that we bought for $35, he started researching on the web, and ended up building three other HD antennae.

HD antenna 2.0 - the first homebuildFirst up was actually the most expensive of the home-builds, since he bought heavy-gauge wire instead of using the coathangers suggested in the YouTube video that inspired it. It was mounted on a piece of Ikea shelving that we had lying around (if it had been the final version, we would have trimmed it back just to a single wooden stick), and consisted of the above-mentioned copper wire ($13), a TV matching transformer (needed on all the antennae to convert the signal to the coax connection to go to the TV, $1) and some screws for that shelving that we already had. With no amplification, it worked as well as the commercial one that is amplified, although we couldn’t find the sweet spot that allowed us to get all 7 HD channels — or at least the 5 that we care about — without moving it around. Also, it could have put out someone’s eye.

HD antenna 3.0 designThat night, he took his copy of the ARRL handbook to bed to brush up on his antenna theory.

The next model, a discone model, never made it past the early prototype stage. Shown here is the cone part (he was still working on the disc part), which would have been covered with aluminum foil. He later found this to not be the right type anyway, but he had fun making (and wearing) the cones.

More research ensued.

HD TV antenna 4.0The 3rd version, a.k.a. HD antenna 4.0, is what we’re sticking with for now. It’s made of two sections cut from aluminum foil (yes, the type from the kitchen) taped to an old wooden ruler. The sections are connected on one side by a 390 ohm resistor (4 for $0.25), and on the other by the TV matching transformer. You can see a close-up of the construction in an earlier phase when he was trying it out on a larger board here; he calculated the exact size of the foil pieces from his antenna theory textbook. Technically, it’s a T2FD antenna.

The antenna-on-a-ruler is attached with 2-sided sticky pads to an old wooden salad server, then mounted on an unused tripod to allow us to easily move it around to find the right spot.

With this configuration, we get the five main HD digital channels that we wanted without moving the antenna: CBC, CTV, CityTV, Global and Sun TV. We can also get Omni 1 and Omni 2 if we move it around, but we rarely watch those so aren’t concerned about it.

Keep in mind that we are less than 1km from the CN Tower, but are west of Spadina and face west, so we’re bouncing our signals off the surrounding buildings. When we tried our Philips antenna (the one that we bought) at a neighbour’s place that has a clear line of sight to the tower, it picked up 7 or 8 HD channels with no fiddling, and several VHF channels as well (since her TV used a single feed for both analog and digital tuners).

I’ve now cancelled our Rogers cable, which will take effect mid-August. The only remaining thing is to use the (currently unused) Philips antenna as a VHF antenna to pick up the lower-range analog channels and feed them to the DVR (which has no digital tuner) and then on to the TV via the HDMI connection — if we get any decent reception on VHF, that will allow us to watch and record those channels.

One Comment

  1. Pat Anderson says:

    I have to tell you…
    I forwarded a link to this to both my parents and my brother.
    Their reactions?
    “Sounds normal to me!”
    Oh — and my brother sez he’s got some copper foil that is adhesive on one side. It’s about the same thickness as what is used on circuit boards.
    Let me know if Damir wants some 😀

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