Antennas shape where a wireless signal actually goes: omnidirectional antennas that spread coverage around an access point, directional and panel antennas that push a link down a hallway, across a warehouse, or between buildings, and the replacement and remote-mount antennas that move a radio's signal away from the metal cabinet it lives in. The radio sets the power; the antenna decides the shape.
Match the antenna to the radio's frequency bands and connector type first - an antenna tuned for the wrong band attenuates instead of amplifying, and wireless connectors look alike while differing in thread and polarity. Then choose the pattern for the space: omnidirectional for open rooms, directional for aisles and point-to-point links. Cable length matters more than it looks, since every meter of coax spends some of what the antenna gained. COLAMCO quotes antennas and cabling with the access points, radios, and readers they serve for business, government, and education networks.