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Azimuth Antenna Patterns

Off-the-Shelf Azimuth Patterns

These off-the-shelf patterns are to be set up per pattern description. Horizontal parasitic lengths and positions will be determined by the frequency.

All antenna distances from structure will be determined as follows:
– Poles: to be determined by diameter of pole (antennas with radomes may require a pole minimum of 4-inch diameter).
– Towers: recorded in (distance from tower) in remarks under pattern.
– Rotation: Leg mounted antennas may be rotated up to 30° clockwise and 30° counterclockwise on leg.
– Any changes from distance to tower, rotation, or pattern will require pattern work. Please contact Shively Sales Department with any questions.

Antenna Model 6815

Custom Azimuth Patterns

All FM antennas react with the structure they are mounted on. In the case of simple mounting structures such as poles, the resulting azimuth pattern may be fairly omni-directional and the horizontal and vertical patterns fairly consistent. As the structure increases in size or complex appurtenances are added in the aperture of the tower, the effect on the pattern can be dramatic. Relatively small changes in mounting such as proximity of the radiator to the tower face or use of parasitic elements (where legally appropriate) can significantly amplify or reduce these effects. Antennas mounted identically but operating at different frequencies may also have different patterns.

While it is not possible to reliably predict most azimuth patterns (with the exception of fairly basic installations such as small poles) we have assembled some sample patterns illustrating typical pattern responses of our most popular antennas. These samples are for education only and it should not be assumed they are achievable for any given installation.

All Shively antenna pattern studies are conducted using exact customer detailed tower specifications, including tower’s face size and bracing. All coaxes, conduit, and other items, such as ladder and other antennas, in the aperture of antenna are modeled in. The tower is then oriented to the actual leg azimuths. Pattern work is conducted in such a way as to minimize terrain interference. Real world coverage will, of course, be dependent on local terrain, buildings, etc.

If you have any questions, please contact Shively Sales Department.

Each pattern has two pages (pattern details & tabulation).

Mounts are separated into three categories: Standard mount is 17.5 inches from tower; standard SM mount is 12.75 inches from tower; standard XL mount is 22.375 inches from tower. All other mounts are CUSTOM mounts. The above mounts will be used on all leg mounts, pickup 2-leg mounts & face mounts. Some antenna bays may be rotated in the mount up to 30 degrees. Frequencies are in three categories: LOW (88.1 to 94.5 MHz); MID (94.7 to 101.3 MHz); and HIGH (101.5 to 107.9 MHz)

Patterns

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