What is a Whip Antenna?
Whip antenna is a common sight on four wheelers these days as most of them have a built in radio, often covering FM and AM broadcast stations. Whip antenna is named so because it is flexible and hence has the movement like a whip when flexed. In some antennas the active element is inside while in yet others you can see a wire spiralling over a fibre glass rod. Popular rubber ducky antenna of hand held VHF and UHF amateur radio are whip antennas. Inner portion of the rubber ducky will have a helical springy wire which makes it flexible as well as cancels out the capacitance of a shortened antenna with its inductance.
Most common type of whip antenna is a quarter wavelength antenna. They can be electrically shortened using a loading coil up to one tenth of a wavelength. Longer 5/8 wavelength whip antennas can be designed for better performance with maximum possible gain in this configuration. Whip antennas are omnidirectional with equal radiation in all directions perpendicular to the axis of the antenna. Radiation from a vertical whip antenna is thus vertically polarized. In case of whip antennas mounted on a vehicle, the metallic body of the vehicle acts as the ground plane.
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