DTV Antenna Project?

One of the things I’m considering with the advent of Digital TV is improving my antenna situation. I’ve had a TV antenna on a rotator for many years inside my attic. It was more than adequate for my needs, and I could reliably get stations from Buffalo, Hamilton and Toronto with little effort.

But the new DTV signals are a little more demanding, at least so far. I get digital signals from all the Buffalo stations, but even when the antenna is aimed right at some of the stations, we on occasion have the picture drop out. DTV signals are all-or-nothing, there is no snow, there is just nothing unless it’s perfect.

So what should I do? The antenna in my attic is only a few feet lower than where one might be if I put it on my rooftop. It’s a VHF/UHF combination antenna of medium size, as big as I could get and still turn inside the attic crawlspace.

I’ve been researching this on the interwebs and combined with my knowledge of electronics and radio communications (35 years as an Amateur Radio Operator) I can weed out the misinformation. But it’s still not totally clear-cut.

First of all, there are a lot of places that will happily sell you a HDTV antenna and promise you the world. It’s an opportunistic business model based on the switchover hype. There is no difference in antennas whether you are getting analog or digital TV, or standard or high definition. No, none, I repeat, despite whatever the seemingly knowledgeable saleperson tells you, there is no difference. Period.

What you do need to know is, after the DTV switchover, where your local stations will end up transmitting. In my area, virtually all of the DTV transmitters are on UHF channels and will remain there. (In some areas, the digital stations are on temporary channels, but will move on June 12.) A channel may be channel 4 (VHF) on analog, but have their digital assignment on channel 39 (UHF). Due to a thing called Virtual Channels, that digital signal will tell you it is whatever the TV station programs it to be, in this case 4.1, 4.2, etc. Why? Because they think it eliminates confusion. The TV people and the FCC (government) think you (the public) are too stupid to understand, so they try to fool you. It must have seemed like a good idea when they thought of it. What ends up happening is it makes it hard to tell what type antenna you need to get for DTV because you can’t just look at the channel number and tell if it is UHF or VHF anymore.

Fortunately, you can get this information online for your local area. antennaweb.org is one of the easier places to get this information. Your local FCC office, TV station (if they answer the phone), or knowledgeable salesperson at Radio Shack can probably help you too. Watch out for the clueless sales guy, though. If you want really nitty-gritty information, look at the FCC’s DTV information site for the link near the bottom for Master List of Television Stations. You can download an Excel file with information on every television station in the United States and what channels they will be on.

A quick sidebar.
Back in the days of black and white TV, before many of you were born, there were 12 TV channels, 2-13. There once was a channel 1, but it was dropped quickly because it’s signals traveled so far, it caused too much interference with the next Channel 1.

Back then, TV sets were full of glass vacuum tubes, some of which were the size of beer bottles. The very-high-frequency, or VHF bands that the TV channels were using were about as high as it was practical to build consumer equipment for.

But technology moved on and the popularity of television made more channels necessary. They eventually added ultra-high-frequency, or UHF channels, channels 14-80. New, acorn tubes and eventually, transistors, made this possible. The UHF frequencies didn’t go quite as far, but that was a good thing, enabling smaller markets to have TV stations. Taller towers and higher power levels equalized that somewhat as well.

There was a time when people asked “My TV only has 12 channels. Will I have to buy a new set?” Of course the answer was then, as it is now, “No, you can add a converter box and get the new channels.”

So, everything old is new again. Eventually, everyone got new sets and the old converters were forgotten. If you find one of those in a garage sale, it’s a collectors item. It won’t help you with DTV, though.

I’m lucky, almost all the stations here are going to UHF. UHF antennas are smaller and should be cheaper to make. They should be less conspicuous on the roof and have less wind load as well so they should last a long time.

Another thing to consider is whether – or not – to use a rotator (sometimes called a rotor). My old rotator’s control box is on it’s last legs. I try not to move it unless I really need to. DTV signals are hard to tune with a rotor. The signal disappears when the signal fades, but the peak of the signal can’t be can’t be seen, because there is no gradual change in the quality of the signal. Beyond that, the signal you see is delayed a couple seconds as the digital conversion is made, making it even more difficult to tell what you are doing. The converter box I have has a signal strength display in a menu that is helpful, but it is still delayed with the picture.

The best way to aim the antenna is by bearing. Again, antennaweb gives you that information. Point the antenna where it tells you and make small adjustments to tweek it. In my location, all the local stations are in two areas; south of Buffalo in the hills, or on Grand Island where two TV stations have 1000-plus foot towers. The Grand Island stations are strong enough here that they can be received with a coathanger, so the antenna pointed at the ones to the south should get both directions. Channel 4 and 7 are marginal at times with my current antenna, but may get better after final changes happen after June 12. In any case, a small improvement should make my reception 100%.

Canada is another story. We normally get 4-5 good signals from southern Ontario, plus a number of weaker ones. Toronto should be a piece of cake, as it’s practically line-of-sight, yet I have only successfully received one station in DTV (5.1 CBLT.) I know there are more, but all the antenna-turning I do only gets them detected enough to get added to the guide, but not received.

Canadian TV reception is sort of a bonus here, but many places have a similar situation, a local market and a second, bit further away source. The only problem for me is all that handy information I get from antennaweb or the FCC for US stations, doesn’t include Canadian listings. I wonder if there is a similar setup for Canada and if it does, will it cover my location for headings?

My current thought for a antenna design is a UHF-only, high-gain, broad pattern antenna. Fortunately, there is such a thing commonly available for UHF TV. A bow-tie reflector type of antenna provides just that sort of thing. They are available from several sources for from $30-100 dollars. I think if I point one south at the Buffalo stations in the hills, I’ll do all right. I might try another on the same mast pointed to Toronto. With the added height and gain, I’m guessing it will at least get the major stations there. I’ll skip the rotator entirely and this setup should be small enough to put on a chimney mount instead of a tripod on the roof.

So what is with the video at the top of the article? Well, before I spend a lot of money on these antennas, maybe the thing to do is try one out. I’ve had a lot of experience building antennas, and can easily duplicate – even improve upon – the construction shown. The video makes it look so simple, and there are many other similar videos out there that make it look even easier. This one at least gives some specific dimensions. Add a reflector by following this page. There is also a good article on a similar antenna with detailed blueprints on a design called a Gray-Hoverman Antenna. Avoid the articles or videos with shoeboxes, coffee cans and no specific plans or dimensions.

The main thing about these simple antennas is, while they may or may not work, holding together an antenna through wind, rain, ice and snow by putting some wood screws and washers into a two-by-four just won’t last. My construction experience might let me improve on that, but I still am in favor of a commercially-made and developed antenna for a long-term solution.

But what they are good for is a trial balloon. Build one for a few bucks and try it out, if it works, go for the big-bucks commercial antenna, it will be worth it. But if you build it reasonably well and are sure it should work, but reception just isn’t there, no other antenna of the same approximate size will do much better. It’s simple physics, an antenna is an antenna is an antenna and the electrons don’t care a whit whether it’s a store-bought antenna or not. It might save you investing in a lot of aluminum you won’t use. Or it might work so well, that you might find out you need less aluminum than you had planned.

Whatever you do, there are some things that are a must to do whether you install a new antenna or upgrade an existing one. Upgrade your lead-in. Nothing lasts forever and lead-in cable is often the weak link in the whole system. Get a good RG-6 cable and replace the old coax. An amplifier might be in order too, especially if you are just marginal with dropouts occasionally. Get a mast-mounted one and put it at the antenna. But this is only a solution if you are close to having the signal you need. You can’t amplify what isn’t there, after all.

When you are done with any changes, rescan for channels. It’s in the TV or converter box menu. You’ll see if you’re getting new channels in just a few minutes.

Posted in Tech Stuff, TV
One comment on “DTV Antenna Project?
  1. Al Gritzmacher says:

    More interesting links to support this article:

    http://www.tvantennaplans.com/

    http://www.remotecentral.com/hdtv/distances.htm and http://www.remotecentral.com/hdtv/

    http://diyfreetv.blogspot.com/2008/01/how-to-build-tv-antenna-from-beer-can.html (A how-not-to example!)

    http://fjallfoss.fcc.gov/edocs_public/attachmatch/FCC-07-138A2.pdf

    http://www.tvfool.com/index.php (Better online location data, includes bearings, both map and compass, and Canadian info. The Google Earth coverage maps are awesome!)

    http://www.antennapoint.com/ (Another station locator. Clean and crisp, easy to follow and use.)

    http://www.digitalhome.ca/forum/forumdisplay.php?f=81 (Canadian forum for OTA antennas and issues.)

    http://www.jedsoft.org/fun/antennas/dtv/xgh.html (“Gold Standard” Grey-Hoverman Antenna)

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