CONTENTS
• INTRODUCTION
• Working
• application
• ADVANTAGES
• Conclusion
• references
A helical antenna is a specialized that antenna emits
and responds to with rotating (circular)
polarization.
These antennas are commonly used at earth-based
stations in satellite communications systems.
This type of antenna is designed for use with an
unbalanced such as
The center conductor of the cable is connected to
the helical element, and the shield of the cable is
connected to the reflector.
CONSTRUCTION DIAGRAM
WORKING OF HELICAL
ANTENNA
 A helical antenna is an antenna
consisting of conducting wire wound in
the form of a helix.
 this antenna can operates in one of two
principle modes,
1. NORMAL MODE
2. AXIAL MODE
NORMAL MODE
In this modes
the dimension of
helix are small
compare with the
wavelength this
antenna typically
used mobile
communication
AXIAL MODE
In this modes the helix dimensions
are at above the Wavelength of
Operation.
The antenna the falls under the class
of waveguide antenna and produces
True circular polarization.
These antenna are best suited for
space communication
AXIAL MODE
EXAMPLE OF HELICAL ANTENNA
• Model 8617-810 - High Gain UHF High Power
Helical Antenna
• For uplinks to UHF satellites, this antenna operates
from 236 - 330 MHz with right-hand circular
polarization with a gain of 12 to 17 dBic.
• Overall length is 10 feet. A special perforated metal
cup reflector increases gain and reduces side lobes.
• The antenna comes complete with an
elevation/azimuth pipe mount allowing for elevation
adjustments from horizon to 65°. Equipped with a
type N connector, this antenna can handle up to 1 KW
of RF
Model 8617-800
UHF 12 - 17 dBic Gain
APPLICATION
•
•
•
•
•
•
High Gain
RH Circular Polarization
Adjustable Tilt Stainless Steel Bracket
Type N Female Connector
DC Grounded for lightening protection
Rugged, Lightweight and Waterproof
• Greater Bandwidth (range 400MHz to
900MHz,14dB)
• greater gain
• more flexibility
• Uni-directional antenna
• crystal clear transmision
We conclude A Helical antenna is
broadband VHF and UHF.
This antenna are right hand
circular polarization.
This antenna can operates in one
of two principle modes,
REFERENCE:
Electronics Communication System
Author
George Kennedy
&
Bernard Davis
Website :en.wikipedia.org/wiki/helical_antenna
and google search