BICONICAL
ANTENNA
1
INTRODUCTION

A biconical antenna consists of an arrangement
of two conical conductors, which is driven by
potential, charge, or an alternating magnetic
field (and the associated alternating electric
current) at the vertex. The conductors have a
common axis and vertex. The two cones face in
opposite directions
WHY BICONICAL ANTENNA
AND CYLINDRICAL DIPOLE
?
Used to produce wide bandwidths, i.e
when coverage over a broad range of
frequencies is required
BICONICAL GEOMETRY
BICONICAL ANTENNA IS FORMED BY PLACING TWO CONES OF INFINITE EXTENT
TOGETHER WHICH IS USED TO ACHIEVE BROADBAND CHARACTERISTICS
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MAIN FEATURES
From 75 MHz to 400 MHz
 Excellent azimuth pattern symmetry
 Low loss, high efficiency

USES:
Biconical (or "Bicon") antennas are often used in
electromagnetic interference (EMI) testing either
for immunity testing, or emissions testing from
25-200 MHz (Commercial specifications) or 30200 MHz (Military applications).
DRAWBACK:
While the Bicon is very broadband, it exhibits
poor efficiency at low frequencies, resulting in
low field strengths when compared to the input
power
UNIPOLE

Whenever one of the cones is mounted on
an infinite plane conductor (i.e the lower
cone is replaced by the ground plane) , it
forms a unipole and its input impedance is
one half of the two-cone structure
CYLINDRICAL
DIPOLE
ANTENNA
9
CYLINDRICAL DIPOLE
Cylindrical dipole antennas are those antenna whose radiation
characteristics are dependent upon frequency(i.e. a wire of
finite diameter and length) and it’s diagram is shown below :-
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CHARACTERSTICS OF
CYLINDRICAL DIPOLE
Another simple and inexpensive antenna whose
radiation characteristics are frequency
dependent.
 It is a special form of biconical antenna when α=0
 -A very thin linear dipole has very narrowband
input impedance characteristics.
-if we decrease l/d ratio the operational
bandwidth will be enlarged.
-This can be done by holding the length the same
and increasing the diameter of the wire.

INPUT IMPEDANCE

For a given length wire its impedance variations
become less sensitive as a function of frequency
as the l/d ratio decreases- more broadband
characteristics can be obtained by increasing the
diameter of a given wire.
PROPERTIES OF RADIATION
PATTERN OF CYLINDRICAL ANTENNA

-It is noted that the patterns are essentially
unaffected by the thickness of the wire in
regions of intense radiation.

-As the radius of wire increases, the minor
lobe diminish in intensity and the nulls are
filled by low –level radiation.
CHARACTERSTICS OF COATED
LINEAR DIPOLE

The optimum bandwidth of the antenna can be
achieved by choosing a lossy dielectric material
with maximum imaginary parts of P and Q and
minimum real parts.-This decreases the radiation
efficiency.
APPLICATIONS
Wideband antennas are needed in television
reception of all channels.
 Radio
