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TV Broadcast Reception
SEARCH *** Columbia ISA Audio/Video • Home TV RECEPTION: VHF and UHF - Analog TV and Digital TV Background In the United States, television stations broadcast over the air in the VHF and UHF portions of the electromagnetic spectrum. VHF stands for Very High Frequency. Stations in the VHF band include TV channels 2 through 13. UHF stands for Ultra High Frequency. Stations in the UHF band are the television channels 14 to 69. In 1952, the FCC allocated 70 additional channels above the VHF television band and called them "ultra high frequency" or UHF band. The channels are 14 through 83. UHF signals, however, due to the physics of radio frequency transmission, are inherently less efficient in the conversion of radio waves to the electrical signals used by the television receiver, and are subject to more losses from some environmental conditions than VHF. Good UHF reception, therefore, requires more attention to antenna installation and set tuning than does VHF reception. On the other hand some VHF channels are subject to certain types of interference to which UHF channels are generally immune. If UHF reception in general is bad, how it's bad can help determine the problem. "Snow" is visual noise caused by a weak signal. poor antenna system, the set itself, or a combination of these. "Ghosts" or multiple images are caused by a signal arriving from two or more directions simultaneously reflected off buildings, trees and mountains. A good antenna system often solves these reception problems. An outdoor antenna is better than an indoor antenna. An indoor antenna is better than no antenna at all. If an outdoor antenna is needed for VHF, you'll almost certainly need an outdoor antenna for UHF. But if good VHF reception can be obtained with and indoor antenna, a loop or other UHF antenna on the set may also work. All indoor antennas can be adversely affected by the walls of a house, inadequate height, and by movement of people in the room-as may be noticed with VHF "rabbit ears." Loop or single bow tie UHF antennas are usually not satisfactory. They are difficult to adjust for maximum signal pick up or for elimination of ghosts. Be sure their lugs are secure to the UHF antenna terminals on the back of the set. The indoor combination VHF/UHF antenna has a multi-position switch to get the best picture. As a rule, this type of antenna is not good for UHF. The rod antenna, or "monopole," is a VHF/UHF antenna found on some portable sets, Normally UHF reception is poor, but can be enhanced when the rod is telescoped to its smaller size. The Best Indoor Antenna If an indoor UHF antenna must be used, the two-bay bow tie with a reflector screen is the best choice. But, keep in mind, outdoor antennas are always better than indoor antennas. Make sure the antenna wires are connected to the UHF terminals on the back of the TV set. Outdoor Antennas There are many different kinds of outdoor antennas available in a wide price range. The kind selected is determined primarily by the geographic location of the receiver. Recommended UHF antennas * Four-way bow tie for metropolitan areas with strong signal * Eight-way bow tie for suburban areas with medium signal Television signals are strongest when the station transmitting tower and the home receiving antenna are in line-of-sight. If the line-of-sight is blocked or weakened by mountains, buildings or trees, the signal, likewise will be weakened or lost. The signal will also grow weaker as it travels farther. "Gain" is the measure of an antenna's sensitivity - and its ability to pick up signals. It is measured in decibels (dB). The farther away from the station tower, the more gain the antenna should have. Gain can also vary from channel to channel. For example, an antenna's advertised gain rating may be at Channel 20, but the gain may be much less at Channel 69. Make sure the dealer guarantees that the antenna purchased is for channels in your area. Where buildings or other obstructions cause "ghosts," an antenna with good directivity is recommended. Directivity is the ability to receive only those signals at which an antenna is pointed. Highly directive antennas have narrow receiving angles (measured to degrees) and high "front to back ratios." To insure the best reception aim the antenna carefully. If a good VHF antenna installation is already on hand, it will probably be less expensive to add a good quality UHF antenna on the same mounting mast, The separate UHF antenna also will permit pointing to VHF and UHF antennas independently. YAGI If all television signals are coming from the same direction, both VHF and UHF reception can be improved. Choose an antenna according to the distance to the most distant UHF station for which reception is desired by installing an all-channel combination antenna. Combining both antennas in a single mechanical structure imposes design problems which make the selection of a well-engineered antenna very important. YAGI COMBO There are several good combination VHF/UHF antennas available. One of the best types combine a "log periodic" VHF antenna with a "yagi" UHF antenna on a single horizontal boom. If the UHF stations to be received are located in different directions from the house (more than 30 degrees apart): * Either use separate antennas with a mixer or a switch (get professional help for this kind of installation.) * Or use an antenna rotator with remote control. The rotator is ideal when signals come from many directions. Lead-in Lines A good lead-in line installation delivers the signal from antenna to set with relatively little loss of strength. Choose a quality grade of either one. Flat ribbon twin lead, shielded twin lead and solid core coaxial cable don't work well for UHF. Lead-in lines deteriorate over time. Lead-in lines over five years old (or less depending on environmental conditions) should be replaced with new cables. Twin Lead * is initially less expensive. * has moderate to poor life; signal loss increases as it weathers and ages. * foam filled type works best. Coaxial Cable (75 ohm line) * costs more initially, but less frequent replacement makes it less costly in time. * occasionally needs matching transformers at antenna and set, and uses * special connectors. * lasts much longer, Has slightly more signal loss than new twin lead, but * loss doesn't increase with age. * foam core works best. * is better at screening local interference. * looks better. A good installation can be made using either type of line. Get professional help if you have special problems like local interference or very weak signals. Few TV sets still have 300 ohm antenna connectors, a matching transformer to connect coaxial cable to the set will be needed. With separate VHF and UHF antennas, separate lead-in lines are used to connect them to their respective terminals on the television set. Most combination VHF/UHF antennas have a connection for a single lead-in line, and in most locations a single high quality lead-in line will deliver good VHF and UHF signals. However, a single line cannot be connected to both the VHF and UHF 300 ohm terminals Instead, a good VHF/UHF "splitter"-rated 300 ohms for twin lead or 75 ohms for coaxial is required. Connect the lead-in line to one end, and the two pairs of wires at the other end to the appropriate set terminals. Splitters (also called "mixers") can also reduce signal strength. So in a weak signal area, use separate lead-ins or add a booster amplifier to the antenna. If a booster amplifier is added, it should be in the line before any splitters, and as close to the antenna as practical. Installation The Best Antenna Location * Higher is usually better. Six to eight feet above the roof should be adequate. * Buildings or other obstructions shouldn't block the line-of-sight to the TV tower. * The shorter the lead-in line, the less signal is lost. * Avoid attaching the antenna to a working chimney. * Fumes are harmful to the aluminum antenna parts. * Heed local ordinance. Tips on Installation * The dealer can advise what hardware to use to mount the antenna. * Be sure the antenna is assembled correctly. Read the instruction sheet carefully. * Check the area to be sure there are no power lines nearby that could touch the antenna, lead-in lines, or metal extension ladder. * Ground the antenna mast electrically, using No. 6 or larger wire and standard ground rod to help protect the antenna and TV set from lightning. * Masts taller than 10 feet need guy wires. * If a separate UHF antenna is used, mount it 4 or 5 feet above the VHF antenna. * Aim the antenna at the TV station tower. Where this is not feasible, a signal reflected from a large building or other obstruction may work. * Experiment with antenna height and aiming, because a few inches can make a big difference. Have someone watch the set and report of reception quality as the antenna position is changed. * Keep lead-in line free of splices and sharp bends. * Keep twin lead at least three inches from metal gutters and pipes by using "stand-off" devices every three feet. * Don't run twin lead and rotator wires through the same stand-offs. * If a rotator is used, leave enough slack in the lead-in line for rotating the antenna. * Secure twin lead to stand-offs or tape coaxial cable to the mast to avoid strain on antenna connections. * Twist twin lead 1/2 turn per foot to prevent wind whipping and to reduce FM or other interference. * Form the lead-in line into a half loop where it enters the house, so rain water will drip off. Seal the entry with a waterproof material. * Excess line coiled in the wall or behind the set can cause signal loss and interference. Multiple Sets More than one television set (or FM radio) may be connected to one antenna by using a multiple set "coupler." Most couplers weaken signals. If signals are weak a coupler and an amplifier may be needed, which substantially increased the cost. It may be cheaper to erect a second antenna. Booster Amplifiers All televisions sets, particularly older ones, add some noise or "snow" to weak UHF signals. A booster (or preamplifier) may reduce the snow, but first be sure a good antenna installation is in place. Keep in mind, outdoor booster antenna are more efficient than indoor models mounted at the set. Maintenance Regardless of initial quality, antennas and lead-in lines gradually deteriorate with age. Pollutants and salt ocean air are particularly destructive. Check the complete installation and hose the antenna with water yearly. Cable TV Systems Cable systems rarely carry a UHF station on its own UHF channel. UHF stations are usually transmitted either on an unused VHF channel or on one of the special cable channels available through a set-top converter furnished to the subscriber. The cable company will provide a listing of channels to which the UHF channels have been converted. Broadcast television stations transmit their signals out over a wide area, typically up to 60 miles, from tall towers with an antenna at the top. The tower is the steel structure that holds the antenna in the air. Sometimes transmitting towers are located on hill tops or tall buildings to increase coverage. There are two major factors that determine the coverage area of a TV station. The first factor is the height of the station's transmitting antenna. To keep the broadcast stations on a somewhat level playing field, the FCC has a limit on maximum antenna height. TV stations west of the Mississippi are restricted to a height of 2,000 feet above average terrain. The second factor that defines coverage is the effective radiated power (ERP) measured in watts. UHF TV stations operate at a higher frequency than VHF. It requires a greater amount of power output for UHF stations to match the coverage area of a VHF station. The FCC limits the maximum visual ERP to 100,000 watts for VHF channels 2 through 6. VHF channels 7 through 13 are permitted a maximum visual ERP of 316,000 watts. UHF stations are permitted a visual ERP of 5,000,000 watts. To receive a UHF TV signal you need an antenna designed for UHF reception. To receive a VHF TV signal you need an antenna designed for VHF reception. Many antennas combine VHF and UHF into one antenna but use different parts of the antenna for VHF and UHF. In 2009, many TV stations in the U.S. shutdown their analog TV signals and instead, broadcast digital TV signals. In addition, many of these TV stations will move from VHF channels to UHF channels. The same bands of VHF and UHF frequencies will be used to send signals out but with digital TV signals. An analog TV will not be able to directly receive digital signals because analog TV sets have a built-in NTSC TV tuner. The NTSC tuner is designed for analog signals. Digital TV signals will need an ATSC TV tuner. Most TV sets sold after 2007 have a built-in ATSC TV tuner designed to receive digital TV signals. To watch digital TV on an analog TV set, you need a converter. The basic converter box will receive local broadcast digital TV stations and convert the signals to analog, showing up on VHF channel 3 or 4 on the analog TV. The same VHF/UHF antennas are used to receive digital TV signals as was used to receive analog TV signals. There is no such thing as a HDTV antenna. Advertising and marketing is very misleading in this regard. If you have a VHF or UHF antenna, you may not need to buy anything when digital TV arrives. However, digital TV signals do present some new challenges which MAY require you to buy a better VHF/UHF antenna. Which antenna should I buy? Two of the more established TV antenna vendors are Channel Master and Winegard but you can buy from local dealers as well. Exactly which antenna you should buy depends on your local conditions so it is almost impossible to say without knowing all your local factors. You may have a VHF station in your area along with several UHF stations or you may only have UHF stations so you would not need a VHF antenna. Your TV stations may be in different directions or all in the same direction and so on. What if I have both analog and digital TV stations in my area? One of the features of some of the converter boxes available in 2009 is the so called ANALOG PASS-THRU feature. If you live in an area where a local TV station is going to remain broadcasting in analog or is a low-power TV station which does not have to convert to digital in 2009, you can select the analog pass-thru feature on the converter box and tune in channels on the TV set instead of the converter box. The converter just passes the signal on thru from the antenna without converting and your analog TV tunes in the channel as in the past. You do not have to modify your antenna installation. You can switch back and forth depending on which channel you want to view. Television signals are strongest when there is a line of sight between the transmitting tower and the home-receiving antenna. The signal is weakened when buildings, hills, and trees block the line of sight. Signal strength also decreases as the distance from the transmitting tower is increased. Gain and directivity are two important specifications to check when selecting a TV antenna. Gain is measured in decibels (dB). It indicates the antenna's sensitivity. There is a greater need for gain the farther you live from the TV tower. If you live close to the tower, a "local" or "suburban antenna" with a gain of 5 to 9dB should do the job. A "near fringe or fringe" antenna has 8 to 10dB of gain. If you live 30 to 35 air miles away, consider a "deep fringe" or "far fringe" antenna with 11 to 16dB of gain. Directivity indicates the antenna's ability to receive only the signals in the direction the antenna is pointing. The spec is measured in degrees. The smaller the number the greater the directivity. A highly directive antenna will have a narrow receiving angle to eliminate signal reflections that can result in ghosting. (Faint double images that appear on the screen). Alignment is critical and may take more time with a directive antenna. A movement of inches can dramatically improve or degrade the signal. Use a directional antenna if ghosting is a problem in your area. Some antennas contain a built-in amplifier to boost the signal. The spec sheets often list the gain of the amplifier, not the gain of the antenna. If the signal is weak leaving the antenna, it will contain noise. The built-in amplifier will not clean up the signal. It will amplify the noise along with the signal. The appropriate solution is a larger antenna with an increased amount of gain. Outdoor Antennas Outdoor antennas are often better than indoor antennas. The mechanical details of an outdoor antenna installation depend upon the selected antenna and the available site. Shops that sell rooftop antennas offer a wide variety of hardware to secure the antenna to any structure. Consult with the shop's sales staff to select the appropriate hardware for your particular situation. Think about having your antenna professionally installed if you feel uncomfortable about working on a rooftop. Here are a couple of general comments about antenna installation. The rooftop is a good location because it is a cost-effective place to obtain the necessary height. As a general rule, higher is better. Six to eight feet above the roofline is usually adequate. Keep the antenna as far as possible from tree limbs, power lines, and any electrical equipment. If the house is located near a heavily traveled highway, the antenna should be placed on the far side of the house away from the highway. The antenna and its mast should be well grounded. Fully extend all elements of the antenna. The antenna should be positioned with the horizontal elements at right angles to the TV tower. Point the short elements toward the location of the TV tower. (Refer to the section on Antenna alignment). Connect the antenna to a television to check reception. If it is unsatisfactory, the antenna will have to be moved or rotated until a strong, reflection-free signal is received. Once the antenna is aligned, it should be locked down tight to prevent it from moving in the wind. Attic Antennas The next best option is to place a full size antenna in the attic. This approach has many limitations. The physical space may not permit optimum orientation. Attic antennas may not provide enough height to clearly receive the signal. Structural elements of the house can block and reflect the signal like metal roofs and metal solar heating protection under your shingles. They will block the signal completely and make an attic antenna useless. If you are installing an antenna in your attic, locate the antenna in a place where all of the elements can be fully extended. It is important to find a spot where the antenna can point to the TV tower. If there is enough room, experiment with different places in the attic. Sometimes the movement of only a couple of feet can make a world of difference with the quality of reception. Indoor Antennas The least expensive antennas are the indoor, set-top variety. If your television set was not provided with an indoor antenna, there are generally four types available for purchase. The UHF loop antenna is the least expensive. It is quite literally a round wire loop. On older television sets, the loop connects directly to the UHF terminals on the back of the set. Make certain that the UHF lugs are securely tightened. Bow Tie antennas are slightly more expensive than loop antennas. The antenna consists of a wire bent in the shape of two connected triangles, hence the name "Bow Tie". The bow tie is often times clipped to the telescoping pole on a set of rabbit ears. Rabbit ears consist of two telescoping poles that stand up like a "V". Some UHF-VHF rabbit ears have a round loop sitting near the base of the "V". UHF is received with the loop. Rabbit ears without the UHF loop usually provide disappointing UHF reception. The Mono Pole is a single telescoping rod that is usually built into a portable television. Normally, UHF reception is poor, but it can be enhanced when the rod is telescoped to a smaller size. Older analog TV sets have separate connections for UHF and VHF antennas. If you are using a loop or bow tie with an older set, make certain the antenna is connected to the UHF terminals with the lugs tight and secure. For best results, locate the indoor antenna near a window, away from electrical sources. You will need to experiment to find the best orientation and placement. It can take a considerable amount of manipulation to optimize for best reception. The movement of people in the room can affect the signal. Indoor antennas usually require adjustment as you switch from station to station. Most people are disappointed with the performance of inexpensive indoor antennas but if your local TV signals are strong enough, these types of antennas work fine. Antenna Alignment A typical TV station broadcasts from a 1,500-foot tower located about 10 to 20 miles from downtown. If the town has several TV channels, chances are that many of them are located in this same area. If you have a combined VHF-UHF antenna, point your antenna in the same general direction for all of the TV stations. If you have one or two TV stations located in a different direction, you may need to invest in a TV antenna rotator. This device has a motor to rotate the antenna under remote control. This allows you to change directions until your reception improves. Do not point your antenna in the direction of the TV station's studio. Chances are their signal does not radiate from the studio location. Consider a separate UHF antenna if you are receiving a snowy or ghosty UHF signal with clear VHF reception. A good quality UHF antenna is optimized for the UHF band. Shop for a high gain and highly directive UHF antenna. The separate antennas will permit you to point both antennas independently for best reception instead of "splitting the difference". RECEPTION ELEMENTS: A good TV picture is the result of many variables including a strong signal broadcast from the TV station, a good antenna and antenna wire, a sensitive TV tuner, a good cable from tuner to TV set, and a good TV set. Any link in the chain which is inferior can produce a bad picture. Choosing and Installing an Antenna for Digital TV There is no single antenna or antenna type that will deliver excellent TV reception in every location. The main factors determining reception are the distance and direction from the TV station transmitters to your home receiving location. Other factors include the transmitter's power and the height of its tower, the terrain between the tower and your antenna, and the size and location of any large buildings in the path of the TV transmission. If you live within a few miles of the TV transmitter, and the signal path is relatively unobstructed, you may be able to get adequate reception using a small set-top indoor antenna. But as you move farther away, getting usable signal strength becomes more difficult. This is where careful antenna selection and installation become essential. Keep in mind that even in the same neighborhood reception conditions often vary from house to house. For that reason, it's best to purchase your antenna from a dealer who offers no-hassle returns with a money-back guarantee. VHF and UHF Like analog TV signals, digital TV signals can be broadcast over two different frequency ranges: VHF (Very High Frequency) and UHF (Ultra High Frequency). The VHF channel range is 2-13 "low-band" VHF is channels 2-6; "high-band VHF is channels 7-13. The UHF channel range is 14-69. Prior to the 2009 transition, most digital stations broadcast in the UHF frequency band, meaning that most viewers would be fine using a UHF antenna. But many stations will change their channel locations with the digital transition. The nation's 1,819 full-power TV stations will look like the following: * Low-band VHF (ch. 2-6): 40 * High-band VHF (ch. 7-13): 445 * UHF (ch. 14-51): 1334 If some of the local stations you want to receive are below channel 14, you may need a VHF/UHF antenna. The FCC requires digital stations to embed a "reference" to their analog channel so viewers won't have to memorize a whole new set of channel numbers. So, your TV might identify a digital station as being in the VHF range when it's actually in the UHF range. Example: A TV station broadcasts digitally on channel 55 but it shows up as channel 5 on your TV because channel 5 is the old original channel. What is the difference between UHF and VHF antennas? Antenna elements are based on the size of the waves they're designed to receive, and VHF frequencies are lower than UHF so the waves are longer, requiring a larger antenna surface to receive them. Uni-directional vs. multi-directional TV antennas Antennas described as "uni-directional" or sometimes just "directional" are designed to receive signals from one direction. "Multi-directional" or "omni-directional" antennas are able to receive signals from all directions. Directional antennas are able to pull in signals from greater distances, and because they "see" in only one direction they are resistant to noise and "multipath distortion" (a problem created when an antenna receives reflections of the desired signal). Because multi-directional antennas "see" in many directions they are more likely to pick up noise, interference, and multipath distortion. What digital TV stations are in my town? Use the tools located here: www.antennaweb.org "ENTER YOUR ZIPCODE" and "ENTER YOUR ZIPCODE" to locate your desired TV stations, this gives you an accurate picture of their direction in relation to your home. If all of those stations are transmitting from an area covering a range of 20° or less, you can probably receive them using a uni-directional antenna. If the transmitters are positioned more than 20° apart, try a multi-directional antenna. As an alternative to a multi-directional antenna, you might consider combining a uni-directional antenna with a "rotor," which lets you remotely rotate the antenna to pick up stations in multiple directions. A rotor is capable of moving your antenna around in a circle in order to capture TV signals better. You mount the antenna on the rotator motor and the motor on a vertical shaft usually on your roof. Then from inside the house you can control the direction of the antenna, rotating it to get a better signal. Also try here for all TV stations in your state and town with a map showing locations of TV towers: W9Wi TV stations database, USA and Canada This site shows you all the TV stations in your area with an abundance of other information. Their signal analysis tool shows each TV station with their locations relative to your location, their output power and much more. TV FOOL Indoor vs. Outdoor antennas The indoor antenna, with compact receiving elements that are under 12 inches long. The outdoor roof-mount, which has 33 elements and measures over 8 feet long. Indoor antennas are generally small, designed to be placed on or near your TV. Outdoor antennas tend to be significantly larger and are intended for roof- or attic-mounting. In general, the larger an antenna's surface area is, the stronger the signal it will provide. The relative strength of the signal an antenna can deliver to a tuner is referred to as "gain" and is measured in decibels (dB). The higher the dB rating, the greater the gain. Nearly all outdoor antennas perform better than even the best indoor antennas. Along with their size disadvantage, indoor antennas have a height disadvantage, and are adversely affected by the walls of a house and even by movement of people in the room. Other sources of household interference include fluorescent lights, computers and cordless phones. Amplified vs. non-amplified antennas One way to help antennas overcome size or height disadvantages, or otherwise enhance signal gain, is through the use of electronic amplification. The amplifier can be built in as it is in many indoor antennas, or it can be a separate device that installs in-line between the antenna and TV. An amplifier that installs on an outdoor antenna or mast is often called a preamplifier or "preamp." Most experts recommend only using an amplifier if you need to. The potential drawbacks of amplifiers are that they amplify noise along with the signal, and they can be overdriven by strong signals, which can make reception worse. If you know of any neighbors who are using an antenna, find out what type/model it is and how well it performs. You could also try calling local TV stations with your antenna questions. It's definitely in their interest to help their viewers improve reception. Antenna cabling: always use 75-ohm coax cable RG-6 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. 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 to your satellite dish. Some VHF/UHF antennas have 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. 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. www.antennaweb.org "ENTER YOUR ZIPCODE" Get Digital TV stations in your area. Television Set Configurations All television sets require some adjustment to receive UHF. It is important to have your television set correctly configured for UHF or you will not receive any signals above channel 13. It does not matter if you have an expensive high gain antenna, if your TV is not set-up for UHF, you will not pick-up UHF channels. Please refer to the owner's manual of your TV set or consult a local dealer for your type of television. Here are a few general notes to help point you in the right direction. Cable Ready Televisions Most television sets sold since 1995 are considered "cable ready". A cable ready set is capable of direct connection to the cable system without the use of a set-top converter box. Cable television systems use essentially the same set of frequencies as the broadcast stations for channel 2 through 13. Cable systems use a different set of frequencies for channels 14 and higher. When a television is configured for first time use, there are several different menu selections that must be set-up. Most TV sets default to the Cable TV (CATV) configuration. Look for a menu selection that offers the choice of CATV or ANT. (Some sets list the choices as CABLE or TV). If CATV or CABLE is selected, you will not be able to receive an over-the-air signal because your television set is looking for a cable channel instead of UHF channel. Be certain to check this menu item for ANT or TV if you are using an outside antenna. Some televisions default to the CATV setting if unplugged from electrical power. Look for the CATV/ANT menu selection if you suddenly lose the ability to view UHF signals. Check the CATV setting anytime you move the TV or experience a power outage. Other televisions have a Cable or CATV switch located on the back of the set near the antenna connector. If your television set has a switch on the back, flip the switch to ANT. If your set is "cable ready", it most likely has a combined VHF-UHF antenna input. Look for a round, threaded connector labeled ANT. Non Cable Ready Televisions If you bought your TV set before 1990, there is a good chance that it is not "cable ready". Some of the older TVs need a fine tuning adjustment to select specific UHF stations. The procedure may require you to tweak tiny knobs located under a panel door located below the screen or on the side of the set. Refer to the owner's manual of your television set for specific instructions. Some older television sets (late 1970s and early 1980s) have rotary tuners. The rotary tuners use round knobs that "click" for each channel position as the knob is rotated. Often times there is a separate knob for the UHF band. To receive Channel 28 for example, rotate the selector to the UHF position on the VHF tuner. (It is usually located between Channel 13 and Channel 2). Next, rotate the UHF knob until Channel 28 is in the active position. If the signal is not clear, rotate the fine tuning knob. It is usually a ring that is located outside or inside the UHF channel selector. (You may have to push in the ring as you rotate it). Slowly move the fine tuning knob back and forth to adjust for the clearest reception. Older television sets have a separate connection for UHF and VHF antennas. Look at the back of your set. If it has a separate connection for UHF, you must have a UHF antenna connected to it or else you will not receive any television station above Channel 13. When in doubt, refer to the owner's manual of your television. The Transmission Line An important element often overlooked is the transmission line. It is the wire that carries the signal between the antenna and the television set. Transmission lines deteriorate with age. If your transmission line is worn-out, you may be looking at a snowy, ghosty signal even if the antenna and television are brand new. For optimum performance, a transmission line should be replaced every five years. That statement does not mean that you should change a five-year-old line if you are satisfied with the existing reception quality. Just be aware that the condition of your transmission line has a major effect on any over-the-air reception. It should be considered for replacement any time that the antenna is properly aligned and over-the-air reception is "not what it used to be". If you are installing new transmission line, it is important to select a quality grade to minimize signal loss. Round coaxial cable and flat twin lead are the two basic types of transmission line. Twin lead cable is less expensive, but it deteriorates faster and is more susceptible to interference. The RG-6 coaxial cable is highly recommended. You should switch to the coaxial cable if you are having reception problems with the twin lead transmission line. Here are a few tips about transmission line installation. Use the most direct route possible between the antenna and the television set. Long cable runs result in signal loss. The shorter the cable, the better the signal. The line should be kept as far as possible from electrical equipment, even if it means a longer cable run. One continuous piece of cable is best. Keep the line free of splices and sharp bends. Amplifiers WEAK SIGNALS: Weak signals show up as a snowy picture on analog TV sets and on digital TV channels as dropouts, pixelation or blank screens. A preamplifier mounted near the antenna can eliminate or reduce the snow or pixelation. Signal strength deteriorates as it travels down the transmission line to the TV. A weak signal will be non-existent when it reaches the television unless it receives amplification before the trip. The pre-amp boosts the signal to offset any loss from the transmission line. An amplifier only prevents additional signal deterioration. If the signal is noisy leaving the antenna, the amplifier will amplify the noise along with the signal. Splitters Households with multiple sets often use passive splitters to send the antenna lead to different televisions. Passive splitters do not require any power to split a signal two to four times. If your signal looks snowy, it is the result of a weak signal. If you are using a splitter, bypass it by directly connecting the antenna to a television set. If the signal improves, you will need to get an amplified splitter. The amplified splitter divides the signal and amplifies each output. Splitters can be 2-way, 3-way, even 4-way and generally cost only a few dollars. Splitters can sometimes be used in the reverse direction as a combiner to allow multiple inputs to a TV. When used as a combiner, only one input can be "active" at a time, otherwise you will get interference. Attenuators If you live close to the TV tower and receive distorted, smeary pictures, the incoming signal is possibly too strong. The problem is easily solved with an attenuator. It is a passive device that simply reduces the strength of the incoming signal without losing clarity. The device can be found at the same place that you bought your antenna. Maintenance and Troubleshooting Start at the television set and work your way toward the antenna. Check the programming (or selector switch) for the setting ANT - CATV or TV - CABLE. Change the setting to ANT or TV. If the television does not have automatic fine-tuning, adjust the fine-tuning for the best picture. If you are still
having reception problems, check for a loose antenna
connection on the back of the TV. If everything is secure and tight,
examine the condition of the line. Transmission lines can suffer damage
from hungry pets and vacuum cleaners. A nicked section of line should
be repaired or replaced. If everything looks fine behind the TV, grab a
ladder and head outside. Cable connections and hookup wiring
diagrams - Home-made TV Antenna Another example is a UHF bow-tie antenna made from coat hangers, a 2X4 stud, copper wiring and an aluminum foil panel. Again, reception can be better than a store-bought YAGI antenna. You may have the materials lying around the house. Get a wooden stud 2X4 (which is actually 1.5 inches by 3.5 inches) about 40 inches long or whatever fits your placement area. Studs are available at your local home building supply store and cost just a couple of dollars if you do not have one already. Get a cabinet door or wood panel. It could even be a stiff piece of cardboard about 16 inches wide by 30 inches high. Cover one side with aluminum foil and attach the panel to the 2X4 at the top with the foil facing the 2X4.
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