TV Antenna Aiming/Pointing & TV Tower Locations

Start by determining the actual locations of the television broadcast towers serving your address. Do not assume that all of your local TV stations transmit from the center of the nearest city or from the same location.

The Channel Master TV Antenna Map & Technical Information Tool allows you to enter your address and view nearby broadcast transmitters along with their RF channels, distances, magnetic directions, and predicted signal strengths. Using your complete street address rather than only a ZIP code provides a more location specific prediction.

Channel Master TV Antenna Map & Technical Information Tool

For a directional antenna, identify the group of towers carrying the stations you want to receive and point the front of the antenna toward that group's magnetic compass direction. If several stations are located close together geographically, one antenna direction can often receive all of them.

iPhone users can also use the Channel Master TV Antenna Compass USA app to assist with antenna orientation.

Channel Master TV Antenna Compass USA for iPhone

The tower's compass direction should be considered the starting point, not necessarily the final antenna position. Terrain, buildings, trees, reflected signals, antenna height, and the immediate installation environment can change the direction from which the strongest usable signal actually reaches the antenna.

After establishing the initial direction, make small adjustments while evaluating reception or signal measurements. Once the best position is found, securely tighten the antenna mounting hardware so that the antenna does not rotate or drift.

These specifications describe where an antenna receives signals from, rather than simply how much gain it provides.

Directivity describes an antenna's ability to favor signals arriving from certain directions while rejecting signals arriving from others.

Beamwidth describes the angular width of the antenna's primary reception area. A narrow beamwidth generally means the antenna is more directional, while a wider beamwidth allows useful reception over a broader range of directions.

Front to back ratio compares reception from the front of a directional antenna with reception from directly behind it. It is normally expressed in decibels. A higher front to back ratio indicates greater rejection of signals arriving from behind the antenna.

For example, Channel Master's directional Pro-Model CM-1776 specifies a maximum UHF realized gain of 9.7 dB and a UHF front to back ratio of 39.1 dB. These are separate characteristics. Gain describes the antenna's ability to concentrate received energy, while front to back ratio describes how strongly it favors the front compared with the rear.

A polar plot is a graphical representation of an antenna's reception pattern. Instead of simply stating that an antenna is directional, the plot allows you to see the relative response of the antenna as the signal arrives from different angles.

First, determine whether the stations are actually spread across widely different directions or whether they form one or two relatively compact tower groups.

Use the Channel Master TV Antenna Map & Technical Information Tool to compare the magnetic direction and predicted signal strength of each desired station.

View your local TV tower locations and directions

If most desired stations are located within the reception beamwidth of a directional antenna, pointing toward the center of the tower group may provide reliable reception of all of them.

If towers are more widely separated, signal strength becomes particularly important. Strong stations can sometimes be received outside an antenna's primary forward beam, while weak stations generally benefit from being closer to the antenna's strongest reception direction.

A multidirectional antenna can be useful when desired towers are spread across a wider angular area. An omnidirectional antenna may be appropriate when sufficiently strong signals arrive from many directions.

Another possibility occurs when two tower groups are nearly opposite one another. An antenna with moderate rear reception can sometimes receive both groups, while an antenna with a very high front to back ratio may intentionally reject the stations behind it.

This is why the antenna with the highest gain or highest front to back ratio is not automatically the best antenna for every tower arrangement. Antenna directivity needs to match the geography of the desired transmitters.

The shortest geographic path between your antenna and a broadcast tower does not guarantee that the strongest or cleanest signal will arrive at the antenna from exactly that direction.

Radio frequency signals interact with the physical environment. Buildings, hills, roofs, metal structures, and other objects can block, reflect, diffract, or otherwise alter the signal before it reaches the antenna.

A reflected signal can therefore arrive from a different direction than the broadcast tower itself.

This effect is especially important with indoor and attic installations. Channel Master's current antenna pointing guidance notes that roofing material, framing, HVAC equipment, wiring, and other objects can reflect or weaken signals inside an attic. As a result, the antenna direction that provides the best reception indoors may differ from the direct compass heading to the transmitter.

Multiple versions of the same signal can also reach the antenna over paths of different lengths. This is known as multipath. Because the paths have different lengths, the signals arrive at slightly different times and with different amplitudes and phases.

ATSC receiver performance guidance specifically addresses multipath handling as an important part of reliable terrestrial digital television reception.

If the delayed signals become sufficiently disruptive, reception can become unstable even when the overall RF signal level appears strong.

This is one reason Channel Master recommends outdoor antenna installation whenever practical. Outdoors, especially when the antenna is elevated above nearby obstructions, the direct path toward the broadcast tower is generally more predictable than inside a building.

In some installations, yes, particularly when signals are strong, but this should not be interpreted to mean that omnidirectional antennas are universally better for attic installations.

An attic can create a complicated RF environment. Signals may pass through roofing materials, reflect from framing, ductwork, wiring, neighboring buildings, and other objects, then arrive at the antenna from directions that do not exactly correspond with the geographic direction of the broadcast tower. Channel Master's pointing guidance specifically identifies this effect as one reason indoor and attic antenna aiming can be less predictable than outdoor aiming.

An omnidirectional antenna such as the Channel Master Omni+ 50 (CM-3011HD) is designed to receive over a broad 360 degree horizontal area rather than concentrating its reception primarily toward one direction.

In a strong signal area, that broader reception pattern can sometimes be advantageous inside an attic because a usable signal may reach the antenna through a direct path, reflected path, or combination of paths without requiring precise directional aiming.

However, the same characteristic can also become a disadvantage.

If strong copies of the same signal arrive from several directions with different delays, the antenna can deliver multiple versions of that signal to the tuner. This is multipath. Modern digital tuners are designed to tolerate a certain amount of multipath, but sufficiently difficult multipath conditions can reduce decoding margin and contribute to pixelation, dropouts, or complete loss of reception. ATSC receiver guidelines specifically include multipath performance because of its importance to terrestrial digital reception.

A directional antenna can sometimes improve this situation by favoring one signal path and rejecting reflected signals arriving from other directions.

Therefore, an omnidirectional attic antenna can work very well where signals are strong and the indoor RF environment is favorable, while a directional antenna may perform better where additional gain or rejection of unwanted reflected signals is necessary.

Testing the antenna at several locations and orientations is often the most reliable way to determine the best attic configuration.

Yes. Over the Air television signals propagate through the atmosphere, and atmospheric conditions can change how those signals travel.

Temperature gradients and variations in atmospheric refractivity can sometimes cause VHF and UHF signals to travel farther than they normally would. Under certain conditions, tropospheric enhancement or ducting can allow distant television signals to reach areas where they are not normally received.

This does not usually mean that the physical broadcast tower has changed direction or that a permanently installed antenna should be routinely reaimed for the weather. Instead, the RF environment around the antenna can temporarily change.

A distant station using the same or an adjacent RF channel may become unusually strong, or the relative strength of direct and reflected signal paths may change. Reception that is normally reliable can therefore temporarily become unstable.

For this reason, antenna aiming should generally be optimized for normal reception conditions, not for a temporary atmospheric event.

If reception changes only during certain weather patterns, times of day, or seasons, the antenna may already be aimed correctly. The changing propagation environment may be the actual cause.

For a permanent installation, the objective is to provide enough signal quality and reception margin that normal variations in propagation do not push the desired channel below the tuner's reliable decoding threshold.