My attic antenna rocks!
Did you see the Super Bowl in high definition?
I did, but I was one of the lucky few in the Charlottesville, Virginia area. The local ABC affiliate broadcasts analog signals only, and our cable provider (Adelphia Communications) offers no HDTV service at all. Satellite operators DIRECTV and DISH only provide high-def network feeds to folks with waivers, which are becoming harder and harder to get.
Richmond is a much larger city than Charlottesville, with many more TV stations broadcasting in digital. I knew of two other Crutchfield employees who'd had success using an attic-mount antenna to receive Richmond stations, so I decided to give it a try. I used the web tools listed on page 1 of this article to locate the stations and learned that my house is over 60 miles from the transmitters. I ordered the same gear my coworkers used: Channel Master's CM4228 "deep fringe" UHF antenna and 7777 preamplifier.
I'd had some rewiring done in my home last year, and I had the electrician run a line of RG-6 cable from the wiring center in my basement up into the attic. That simplified the installation a lot. I used a pocket compass to aim the antenna (the CM4228 is very directional so if your aim is off just a little it can really hurt your reception). My roof actually has two layers of asphalt shingles, so I wasn't at all sure I'd be able to pull in signals from so far away.
First, I tried just the antenna alone, and while I could receive most of the Richmond stations, I wasn't getting CBS, and Fox was breaking up occasionally. Adding the preamp did the trick. Before installing the antenna/preamp combo, I was getting only spotty HD reception of Charlottesville's NBC station using a Terk set-top antenna (HDTVi). Now, my reception of CBS, NBC, ABC, Fox, and PBS out of Richmond is rock-steady and clear as a bell — from 63 miles away! And I'm still getting NBC in Charlottesville, too.
Steve KindigAntenna cabling: always use 75-ohm coax cable
Whether you want to install an antenna on your roof, on a pole, or in your attic, using the right kind of cable is crucial. The two types of wire commonly used to connect an antenna to a TV are 300-ohm twin-lead and 75-ohm coax. Twin-lead is a flat wire, while coax cable looks like the round cable installed in homes for cable TV service. In recent years, virtually all TVs have gone to the coax-style connection.
Coax cable is superior to twin-lead in every way and should be used if possible. Even if your home has an existing run of twin-lead cable, consider replacing it with coax. Twin-lead is not shielded and the entire length of wire can act like an antenna, which may cause reception problems. Coax cable is shielded, which prevents signals from leaking into or out of your system. Coax cable is also unaffected by your home's electrical wiring or by contact with metal objects. And coax has a much longer lifespan than twin-lead.
Antenna cabling tips:
- For the best performance and reliability, use high-quality UL-rated dual- or quad-shield RG-6 cable
- Cable should run as directly as possible from the antenna to the tuner; try to minimize the number of splices
- Avoid sharp bends in the cable as they can impair performance
- If the antenna is installed outdoors (including on the roof) run the cable into the house through an attic or basement if possible; never run the cable through a window or door
- Outdoor antennas should be grounded for lightning protection. Place a grounding block where the antenna cable enters the house and run a wire from the grounding block to your home's ground rod. This is not only an important safety consideration but also a potential code requirement
- Outdoor connections should be protected from exposure to the elements by applying silicone grease to the connection and covering it with a weather boot
Tips on installing an outdoor antenna
Large outdoor antennas can be installed on a roof or a free-standing pole, and many can be installed in an attic. For the best results, your antenna should have the clearest possible "view" of the transmitter tower. That is achieved with a roof- or pole-mount installation (attic-mount installation is covered below).
People living in neighborhoods with homeowners' associations may wonder if association covenants can restrict antenna use. The Telecommunications Act of 1996 prohibits restrictions that impair the installation or use of antennas to receive video programming. It covers digital satellite dishes, TV antennas, and wireless cable antennas.
Most TV antennas designed for roof- and/or attic-mounting include a mounting mast. Here are some general tips for roof-mount antenna applications:
- Locate and avoid power lines and other wires in the work area
- Do not climb on a wet or icy roof
- Do not attempt high installations on windy days
- Do not climb onto a roof when there is no one else around
- Do not install an antenna under large, overhanging tree branches if it can be avoided
- If possible, avoid chimney-mounting an antenna as smoke and gases from the chimney can impair the antenna's performance and shorten its life
When you're aiming the antenna, use a compass to ensure your antenna is accurately and precisely oriented toward the signal source. At this stage, it's best to have a helper who can check picture quality and relay the information to you. (Most, but not all HDTVs and HDTV tuners include an onscreen signal strength meter.) Be sure to check the picture on all channels you want to receive before securing the antenna in place.
If you plan to use an antenna in addition to a digital satellite TV system, you have a couple of options. One fairly easy solution is to attach a "clip-on" antenna like Terk's TV44 to your satellite dish. This amplified VHF/UHF antenna has built-in "diplexers" that combine the satellite and antenna signals onto a single cable, which can eliminate the need to run new cable. You'll need to install a diplexer at each satellite receiver to provide separate connections to the "Satellite In" and "Antenna In" jacks. A clip-on antenna usually performs better than an indoor antenna, but not as good as a larger outdoor antenna.
Attic installation
Compared to roof-mounting, installing an antenna in your home's attic has several appealing advantages: installation is much easier, the antenna is hidden from view, and the antenna and connections are not directly exposed to harsh weather.
Channel Master CM4228 antenna mounted in an attic. The antenna is about 40" square. The small box sprouting cables near the bottom of the mast is part of the Channel Master 7777 preamplifier.
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The main disadvantage of attic-mounting is poorer reception. As an example, a single layer of asphalt shingles over a standard plywood roof creates a 30%-50% reduction in signal strength. Attic-mounting can be an effective option in areas where strong signals are present. To maintain adequate signal strength, an amplifier or preamp is often used.
Other potential obstacles to attic-mounting include a metal roof, aluminum siding, metal gutters, or foil-backed insulation in your walls or under the roof. Any of these conditions can result in signal interference or blockage. If that happens, try installing the antenna in a different location. For the best reliability and performance, mount the antenna to a mast and don't let the antenna touch the attic floor.
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