whip antenna

Download Whip antenna

Post on 23-Jun-2015

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  • 1. BY: Niaz Hussain niaz.hussain@iba-suk.edu.pk Department Of electrical Enginnering at Sukkur IBA

2. A whip antenna is an antenna consisting of a single straight flexible wire or rod. The bottom end of the whip is connected to the radio receiver or transmitter. They are designed to be flexible so that they won't break off, and the name is derived from their whip-like motion when disturbed. 3. This design goes back to the 1890's when Marconi set out to prove that radio signals could travel long distance.To achieve the goal, he had to stretch a long wire above the ground. Due to the low frequencies, thus a long wavelength, the wire had to be long. He also found that the wire worked better when it was high above ground. 4. Varieties in Design: Often whip antennas for portable radios are made of a series of interlocking telescoping metal tubes, so they can be retracted when not in use. 5. The whip can be made as a trace on a printed circuit board (PCB).This is very practical at frequencies over 800 MHz. 6. Length: The length of the antenna rod is determined by the wavelength of the radio waves used. The most common length is approximately one-quarter (Lambda/4) of the wavelength, called a "quarter-wave whip" . To reduce the length of a whip antenna, an inductor (loading coil) is often added in series with it. The inductor is always like helix, which distributes the inductance along the antenna's length. Which improves the radiation pattern, and makes antenna more flexible. 7. Gain and radiation resistance: If mounted above a perfect ground plane, a quarter-wave whip has a gain twice that of a half wave dipole, or 5.19dBi. radiation resistance of 36.8ohms. However without a ground plane the gain is reduced and the radiation resistance increased. Whips mounted on vehicles use the metal skin of the vehicle as a ground plane. In hand-held devices usually no explicit ground plane is provided, and the ground side of the antenna's feed line is just connected to the ground on the device's circuit board. [Therefore the radio itself, and possibly the user's hand, serves as a rudimentary ground plane. 8. Radiation Pattern: 9. Features: A whip-style antenna provides exceptional performance and stability. A straight whip has a wide bandwidth and is easily designed and integrated. A whip can also be made by cutting a piece of wire or rod to the appropriate length. 10. It can be used in HF and UHF bands. widely used for hand-held radios such as cell phones, cordless phones, walkie-talkies, FM radios, boom boxes, Wifi GPS receivers. 11. Also attached to vehicles as the antennas for car radios two way radios for police, fire and aircraft. Larger versions mounted on roofs or radio masts are used as base station antennas for police, fire, ambulance, taxi and other vehicle dispatchers.

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