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Antenna

This page is a chapter in 'BASE Wiki About BASE Jumping'

Antenna (A) is the 2nd object of the B.A.S.E. Acronym. Please note each of the 4 main object types have their own special considerations and optimal wind conditions.

Antenna Objects are man-made structure typically used for communication purposes. They can range from very low at about 200 feet to very high at 2,000 feet.

Low towers are commonly used for mobile telephones and are often located in populated areas. The taller antennas are usually found further off the beaten path, and generally offer less chance of being seen and have much larger/better landing areas.

Two common considerations when choosing an antenna to jump, besides access and LZ, are guyed wires (object strike) and the type of antenna (due to radiation concerns).

'Freestanders' are any antennas that do not have support wires. The appealing attributes of these objects are: 1) no wires to avoid under canopy, 2) easier to climb because they lean in, and 3) some of them offer huge platforms on top for running exits. The down side of a freestander is they are always low, meaning slider-down/off and usually range from 190 to 500 feet.

'Guyed' are any antennas that have support wires. They typically offer a jumper much more altitude but take longer to climb and often require a specific wind direction. The wires on a guyed antenna are usually organized into three groups making 3 distinct sides known as 'Sectors'. On a guyed antenna, the best wind conditions would be to have the wind cleanly bi-sect the sector with the best landing area. Occasionally an elevator can be used to reach the top which is a beautiful but rare thing.

Most jumpers agree that the optimal wind condition for any antenna (or crane) is a tailwind equal to the forward speed of your canopy that would make an object strike very unlikely, even with an off-heading deployment.

Heading performance on short delay slider-up deployment is not great, hence most jumpers prefer to avoid jumping from a guyed antenna with certain configurations.

Common antenna types include: AM, FM, TV, Cell, Communication, and dead. AM towers are very dangerous because the entire structure is transmitting, irradiating the jumper during the entire climb. The others types are relatively safe if you avoid the apparatuses that actually broadcast a signal. Never rest near a stinger, dome, horn, or array!!

The best type of antenna for the conservative jumper is one that is not broadcasting any signal. These will either be structures that are currently not in use or after their broadcast day has completed. To locate one of these gems do your research.

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