Wideband Circular Polarization Patch Antenna

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BGU university - Electrical Computing
Engineering Department
Wideband Circular Polarization Patch Antenna
Based on Ferrite Disk Coupling.
Students Shlomi Kedem, Ido levitin Advisors
Prof. Reuven Shavit , Dr. Eugene Kamenetskii, Mr.
Michael Sigalov p-2008-070
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Outline
Introduction
Previous works
Ferrite properties
Antenna design
Antenna performances
Conclusion and Further steps
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Introduction
Radio signals are reflected or absorbed depending
on the material they come in contact with.
Because linear polarized antennas are able to
attack the problem in only one plane, if the
reflecting surface does not reflect the signal
precisely in the same plane, that signal strength
will be lost.

• Using of circularly polarized microstrip antennas
  is a low cost and effective method to overcome
  such problems.

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Previous works
Rectangular patch antenna printed on magnetized
ferrite substrate
CP Patch generated by two orthogonal feed lines
Circular patch antenna tuned by magnetized
ferrite post
CP Patch generated by perturbation segment
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Ferrite properties
A ferrite is a magnetic material that allows an
electromagnetic wave to propagate through.
Microwave ferrite devices permit the control of
microwave propagation by a static or switchable
DC magnetic field.
The DC bias field, internal to a ferrite sample
is generally different from the externally
applied field, because of the boundary conditions
at the surface of the ferrite.
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Magnetic dipole precession and equation of motion
- Magnetization
- Magnetic moment
- Unbalanced electron spins (magnetic
dipole) per unit volume
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Wave propagation in a ferrite medium
Magnetic dipole
ferrite media
x
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Ferrite properties
Argument is given in the graph (the
externally applied field is 2230 Oe)
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Antenna Design
Stage 1 Ordinary patch antenna without ferrite
with resonance frequency at 1.5GHz. Parameter
study 1. excitation line position, width and
length. 2. patch radius.
Stage 2 Stage 1 patch antenna with single
ferrite Parameter study 1. ferrite disk
position, radius and thickness.
2. patch radius and excitation line width ( due
to ferrite influence )
Stage 3 Stage 2 patch antenna with double
ferrite Parameter study 1. ferrite disks
position. 2. patch radius and
excitation line width (due to ferrite influence )

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Ordinary Patch Structure
H field
J surf
Vector Poynting
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Ordinary Patch Structure
resonance frequency at 1.5GHZ
excitation line width 3.5mm
excitation line width 3mm
excitation line width 2.5mm
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Single Ferrite Structure
H field
J surf
Vector Poynting
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Single Ferrite Structure
Return Loss( ) of the single ferrite design
Axial ratio of the single ferrite
3dB line
new resonance frequency with linear polarization

resonance frequency for dominant
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Single Ferrite Structure
results for positions (2),(3),(4) with 6mm, and
position (2) with 10mm
(1) position (-11mm,-12mm) (2) position
(-14mm,0mm) (3) position (-11mm,12mm) (4)
position (0mm,11mm)(5) position (0mm,0mm)
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Js for 1.51 GHz
Double Ferrite Structure
H field for 1.51 GHz
Vector poynting for 1.51 GHz
H field for 1.37 GHz
Js for 1.37 GHz
Vector poynting for 1.37 GHz
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Double Ferrite Antenna Simulation Performances
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Double Ferrite Antenna Simulation Performances
Return Loss( ) of the double ferrite design
Axial ratio of the double ferrite
3dB line
resonance frequency for dominant
resonance frequency for dominant
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Double Ferrite Antenna Simulation Performances
LHCP/RHCP/Total Gain at 1.51GHz
LHCP
LHCP/RHCP/Total Gain at 1.37GHz
RHCP
RHCP
LHCP
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Antenna Product
Microstrip feed line
Ferrite disks
Circular patch
ground plane
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Conclusion and Further steps
Dual frequency capabilities with the advantages
of CP at 1.51 GHz and 1.37 GHz with LHCP and RHCP
respectively.
By Changing the polarity of the magnet, we can
switch between the polarization qualities.
The antenna has simultaneous transmit/receive
capabilities, at different frequencies.
Further work to be carried out Testing the
antenna at Elta Antenna Laboratory
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Antenna Performances
2D view of the Vector Poynting on the patch at
1.51GHz
2D view of the Vector Poynting on the patch at
1.37GHz