A whip antenna consists of a straight flexible wire connected at one end to a radio transmitter or receiver. It is designed to be flexible to avoid breaking. Whip antennas work best when they are high above the ground with a clear view in all directions. They are commonly used in portable radios, cell phones, walkie-talkies, and as vehicle antennas for car radios, police radios, and aircraft. The length of the whip antenna is typically a quarter of the wavelength of the radio waves used.

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.

7.  The whip can be made as a trace on a printed
circuit board (PCB).This is very practical at
frequencies over 800 MHz.

8. 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.

9.  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.

10.  Radiation Pattern:

11. 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.

12.  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.

14.  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.