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A dipole antenna belongs to a sort of radio antenna,which
contains a simple wire,in which a driven element was fixed.And it
has something to do with the 2 major metal conductors who are
keeping neck and neck with esch other to supply us with rod or
wire.When the Heinrich Hertz who is the German physicist, did
experiment with radio waves around 1886,he discovered the dipole
antenna.In theory,a dipole antenna is actually the simplest
practical antennas of all. Traditionally, dipole antenna was once
used in television antennas which looks like the "rabbit
ears" .What’s more, dipole antenna works in a great range of
antennas as the driven element.And Yagi relys on dipole antenna a
lot.
There are many kinds of dipole antennas,such as
half-wavelength dipole, folded dipole, Hertzian dipole
,crossed-dipole antenna and so on. Half-wavelength dipole is a very
special case,for every wire is actually the 1/4 of the wavelength
and the total wavelength is 1/2 of the wavelength.A folded dipole
is well-known as the half-wave dipole,which has a wire connected to
its ends of two sides. Hertzian dipole is a very short dipole and
Hertzian dipole can not exsit in reality. Crossed-dipole antenna,
is a kind of antenna that can be used to reduce clutter and
enforce the GPR serveys.GPR is short of ground penetrating
radar.The crossed-dipole antenna can be used to transmit antennas
as well as receive antennas. The crossed-dipole antenna is often
seen in some areas such as environmental and engineering GPR
investigations.However,because of its lackness of sensivity to
stratigraphy,it is not so pupolar in the GPR serveys.
Then you may curious about the way to make a simple dipole
antenna.It is not so difficult to make it anyway,for the materials
are easy to prepare,all you need are the wire with different
lengths, some co-ax cable and lastly,a connector.To begin,connect
cut wire to choc block and to the 75 ohm co-ax.Then,choose the
right place to hang the antenna so that the very element pointing
upwards,when connected to the central part of the co-ax.Lastly,we
should make it for sure that there is no mismatch.Instead,by using
a balun, the co-ax’s unbalanced impedance should in no way to match
with a dipole’s balanced 75ohm impedance.
To make a summary,from the text we get to know the definition of
dipole antenna and its different kinds of dipole antennas with
various advantages and functions.And from the text,we learn how to
make a simple dipole antenna.we also know some background
information of dipole antenna for example, it is Heinrich Hertz who
invented dipole antenna.
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