This document discusses ferrite phase shifters. It begins by defining ferrites as magnetic materials used in microwave applications due to their electric and magnetic anisotropy. It then discusses three main types of ferrite phase shifters: latching ferrite phase shifters, dual mode ferrite phase shifters, and rotary field ferrite phase shifters. Latching ferrite phase shifters include twin toroid designs that induce a phase shift by modifying the transmission line propagation constant. Dual mode ferrite phase shifters convert signals to circular polarization to interact with a ferrite rod under a bias field, producing a phase shift. Rotary field ferrite phase shifters rotate a ferrite half-wave plate to produce a phase

1. FERRITE PHASE SHIFTER
DEPARTMENT OF ELECTRONICS ENGINEERING
PONDICHERRY UNIVERSITY
SUBMITEED BY:
RIGVENDRA KUMAR VARDHAN
REG. NO.-14304022
M.TECH ECE 1ST YEAR

2. Contents
1. Ferrite
2. Phase Shifter.
3. Parameters Of An Electronic Phase Shifter
4. Classification
5. Ferrite Phase Shifters
6. Features
7. Latching Ferrite Phase Shifter
8. Dual Mode Ferrite Phase Shifter
9. Rotary Field Ferrite Phase Shifter
10. Applications.
11. Conclusion.
2

3.  Materials having electric anisotropy (tensor permittivity), and magnetic
anisotropy (tensor permeability). Some of the most practical anisotropic
materials for microwave applications are ferrimagnetic compounds, also
known as ferrites, such as yttrium iron garnet (YIG) and materials
composed of iron oxides and various other elements such as aluminium,
cobalt, manganese, and nickel.
 In contrast to ferromagnetic materials (e.g., iron, steel), ferrimagnetic
compounds have high resistivity and a significant amount of anisotropy at
microwave frequencies.
 The magnetic anisotropy of a ferrimagnetic material is actually induced by
applying a DC magnetic bias field. This field aligns the magnetic dipoles in
the ferrite material to produce a net (nonzero) magnetic dipole moment, and
causes the magnetic dipoles to precess at a frequency controlled by the
strength of the bias field.
FERRITE 3

4.  A microwave signal circularly polarized in the same direction as this
precession will interact strongly with the dipole moments, while an
oppositely polarized field will interact less strongly.
 Since, for a given direction of rotation, the sense of polarization changes
with the direction of propagation, a microwave signal will propagate
through a magnetically biased ferrite differently in different directions.
 This effect can be utilized to fabricate directional devices such as
isolators, circulators, and gyrators.
 Another useful characteristic of ferrimagnetic materials is that the
interaction with an applied microwave signal can be controlled by
adjusting the strength of the bias field. This effect leads to a variety of
control devices such as phase shifters, switches, and tunable resonators
and filters.
FERRITE 4

5.  A Phase Shifter is two-port device whose basic function is to provide a
change in the phase of RF signal with practically negligible attenuation.
 A phase shifter is a device which provides variable insertion phase in a
microwave signal path without altering the physical path length.
 Most phase shifters are two port devices characterized by low insertion
loss and low VSWR.
PHASE SHIFTER 5

6. 6

7. PARAMETERS OF AN
ELECTRONIC PHASE SHIFTER
 Center frequency of operation
 Bandwidth
 Insertion loss (for 360° phase shift)
 VSWR or return loss
 Switching time (for digital operation) or time required for 360° phase
change (for analog operation)
 Switching power or energy (for digital operation) or dc holding power
(for analog operation)
 Phase error
 Power-handling capability(peak and average)
7

8. CLASSIFICATION OF ANALOG PHASE
SHIFTERS
Analog Phase Shifters
SemiconductorFerrite
8

9. Ferrite Phase Shifters
Non Reciprocal Reciprocal Non Reciprocal Reciprocal
• Twin-toroid
• Toroidal
• Helical
• Circular toroid
in circular
waveguide
• Toroidal
latching in
stripline
• Slow-wave
structure in
stripline
• Microstrip
meander line
• Toroidal co-
planar
waveguide
• Dual mode
• Faraday
rotation
• Microstrip
meander line
• Stripline
latching
Waveguide Planar/MIC 9

10. Semiconductor Phase
Shifters
Reciprocal Reciprocal Non reciprocalNon reciprocal
P-I-N
diode
GaAs FET
(Passive)
• Switched line
• Hybrid coupled
• Loaded line
• High-pass low-
pass
• Switched
network
GaAs FET
(active switch)
• Switched path
GaAs FET
(passive)
GaAs FET
(active switch)
• Switched line or
loaded line
• Hybrid coupled
• High-pass low
-pass
• Switched path
DGFET
Planar/hybrid MIC Monolithic 10

11. FERRITE PHASE SHIFTERS
THEORY
 As the permeability increase the effectiveness of the ferrite rod increases
since guided wavelength is equal to wavelength in space divided by
effectiveness(permeability),hence guide wavelength decreases, which
result in a change or RF insertion phase.
 Several switching speeds.
 Works near saturated state.
 Phase bits are determined by
the length of the toroid
FEATURES
 Fast Rise Time
 360° Phase Shift
 Remote Controlled
11

12. Contd…
 Ferrite phase shifters are classed as either reciprocal or nonreciprocal,
depending upon whether the variable differential phase shift through the
device is a function of the direction of propagation.
 Further, ferrite phase shifters may be latching or non-latching, depending
upon whether continuous holding current must be supplied to sustain the
magnetic bias field.
 Phase shifters may be used in a variety of ways in microwave systems, but
their application in electronic scanning antennas is the single most
important factor influencing their development.
 Three types of ferrite phase shifters are generally encountered in
microwave circuits and systems.
1. Latching Ferrite Phase Shifter
2. Dual Mode Ferrite Phase Shifter
3. Rotary Field Ferrite Phase Shifter
 The twin toroid is a latching, nonreciprocal device; the dual-mode is a
latching, reciprocal device and the rotary-field is a non-latching reciprocal
device.
 All are constructed from ferrite materials which have a square hysteresis
loop. The latching phase shifters use either a closed magnetic circuit or a
magnetic circuit with very small air gaps.
12

13. Contd…
 The relative permeability of the ferrite is controlled by adjusting the flux
level existing in the closed magnetic circuit.
 These phase shifters effect a phase change by modifying the propagation
constant of the transmission line which contains the ferrite.
 The rotary-field phase shifter on the other hand is a true phase shifter, as
opposed to a variable line length device, since it realizes phase shift by
rotating a fixed amplitude magnetic bias field.
 This results in a modulo-360 phase control characteristic as well as
inherently low phase error since the phase shift is controlled by the
angular orientation of the bias field rather than the magnitude of the bias
field.
 The angular orientation may be controlled easily and accurately by
controlling the current into a pair of orthogonal windings.
 Two factors influencing the frequencies for which physical realization of
these phase shifters is practical are the device geometry and the
saturation magnetization of the ferrite used to construct the device.
13

14. Latching Ferrite Phase Shifter
 The first latching phase shifter used a toroidal geometry.
 The modern version of this device, the twin-toroid, is shown in Fig. 3.
Analytical models have been developed by Ince and Stern and Allen.
14

15. Contd…
 The dielectric spacer is used to concentrate the rf energy in the centre of
the waveguide.
 The walls of the toroids, which contact the dielectric spacer, are located
in those regions of the waveguide which support a circularly polarized
magnetic field.
 Letting ß+ designate the propagation constant when a positive bias field
saturates the ferrite and ß- be the same for negative bias field, the
maximum amount of variable insertion phase per unit length is (ß+ - ß-).
 Any amount of phase shift less than this is achievable by reducing the
bias field level. The values of ß- and ß+ interchange with the direction
of propagation.
 One important characteristic of the twin toroid phase shifter is the
extremely broad instantaneous r-f bandwidth achievable.
15

16. Contd…
 Figure 4 is reproduced from Ince and Stern and illustrates that the differ -
ential phase shift can be made to be independent of frequency with proper
choice of design parameters.
16

17. Contd…
 These phase shifters have been realized with bandwidths greater than an
octave. Attention must be given to mode control in these devices since the
switching wire is enclosed by the waveguide, thus allowing a TEM mode
to propagate, as well as higher order LSE and LSM modes.
 A photograph of a twin toroid phase shifter in a waveguide housing is
shown in Fig.
 The toroids are located in the centre of the structure where the housing
size is reduced. Dielectric matching transformers are placed at both ends
of the toroids to match into the air-filled, rectangular waveguide input and
output ports.
 The switching wires are threaded through holes in the narrow walls of the
waveguide and attached to posts for connection to the electronic driver.
17

18. Dual Mode Ferrite Phase Shifter
 The dual-mode phase shifter is shown in Fig. 6. This phase shifter uses
either a circular or quadrantally symmetric ferrite rod which is metallized
to form a ferrite-filled waveguide.
 The cross-section must have this symmetry so that circularly polarized
energy will propagate through it without change of field distribution.
 At either end of the rod, nonreciprocal, quadrupole-field ferrite polarizers
are used to convert linearly polarized fields to circularly polarized fields
and vice-versa.
18

19. Contd…
 External latching yokes are fitted to the ferrite rod to provide a closed
magnetic path for latching operation.
 Resistive films are incorporated in dielectric sections at both ends of the
rod to absorb undesired cross-polarized fields.
 Linearly polarized energy incident on port 1 of the unit is converted to
circular polarization by the quadrupole-field polarizer.
 This circular polarized wave has a rotating transverse magnetic field
which interacts with the partially magnetized ferrite in the variable field
section and receives an insertion phase dependent upon the magnitude and
direction of the variable bias field.
 This may be described by a variable relative permeability ranging from µ-
for negative saturation to µ+ for positive saturation.
 If ß+ is defined as the propagation constant for negative saturation, the
variable insertion phase per unit length is (ß+ - ß-).
 The circular polarization is reconverted to linear polarization by the second
quadrupole-field polarizer and the resistive fil absorbs any undesired sense
of linear polarization that might occur because of small alignment errors.
19

20. Contd…
 For signal transmission in the reverse direction, the quadrupole-field
polarizer on the right converts incident linear polarization to the opposite
sense of circular polarization in the variable field section.
 However, the same amount of phase shift is produced since the direction of
propagation has also changed, which results in transverse-plane rotation of
the r-f circularly polarized magnetic field in the same direction as before,
and therefore, identical interaction occurs with the magnetized ferrite.
 A family of dual-mode phase shifters is shown in Fig illustrating sizes of
C-, X- and Ku-band units in metal housings. The C-band unit (on the right)
is designed to be an element in a transmission lens and is complete with
electronic driver. The X-band unit (on the left), also with electronic driver,
is connected between a waveguide feed manifold and the radiating ground
plane. Finally, the Ku band device (centre front) is designed to match into
ridge waveguide on either end.
20

21. Rotary Field Ferrite Phase Shifter
 A series of rotary-field phase shifters are shown in Fig for S-, C-, X- and
Ku-band frequencies.
 All of the units have been produced in more than prototype quantities
and all use either free convection cooling, forced air cooling are attached
to a cold plate.
 The rotary-field phase shifter is the electronic equivalent of the rotary
vane phase shifter described by Fox.
 Linearly polarized r-f energy propagating in the input and output
rectangular waveguides is converted to circular polarization in a ferrite
half-wave plate by the combination of a waveguide transition and a
reciprocal quarter-wave plate.
21

22. Contd…
 The half-wave plate is a nonreciprocal differential phase shift section
whose angular orientation is controlled by the external magnetic bias field.
 The r-f signal receives differential phase shift of twice the relative rotation
of the half-wave plate is reconverted to the TE10 rectangular waveguide
mode by another reciprocal quarter-wave plate and waveguide transition.
 Resistive film to absorb any cross-polarized energy is generally
incorporated into the waveguide transitions.
 Since the half-wave plate need provide only 180 degrees of differential
phase shift, minimum length of ferrite is utilized.
 Physically, the rotary-field phase shifter consists of a composite ferrite
/dielectric rod which has been coated with a thin metal layer to form a
circular waveguide, a drive yoke which provides the rotatable magnetic
field and a housing which generally incorporates the input and output
waveguides.
 Cooling fins, as shown in photograph of Fig. 11, can be machined in the
housing to provide for increased power dissipation.
22

23. Contd…
 Yttrium-iron garnet is used almost exclusively in these phase shifters
because of the extremely low dielectric loss tangent and good power
handling capability exhibited by garnets.
 For the garnets used, the peak r-f power level is inversely proportional to
the saturation magnetization.
23

24. Contd…
 Thus, r-f power handling capability may be achieved at the expense of
greater length (weight).
 The ferrite half-wave plate uses a quadrupole field geometry which must
be rotated to effect phase shift.
 This is accomplished by fitting a ferromagnetic yoke over the half-wave
plate portion of the ferrite/dielectric rod waveguide. The yoke has a
number of slots in which are wound two sets of interlaced coils each of
which generates a four-pole field.
 The two windings are referred to as the “sine” and “cosine” windings
because of the patterns generated by their exciting currents.
 Applying a current Im sin θ to one winding and Im cos θ to the other
winding results in the four-pole bias field being oriented at angle θ/2
which yields a phase shift of twice the relative rotation of this angle from
a prescribed reference.
 The control power necessary to provide the magnetic bias field is
inversely proportional to the number of turns in the control winding.
24

25. Contd…
 This implies that a large number of turns are desirable in order to minimize
this power requirement.
 The circuit time constant on the other hand is directly proportional to the
number of turns which would imply that the number of turns be held to a
minimum since small switching times are generally desired.
 If there are no constraints on the phase shifter diameter, the number of
turns is generally determined by the control power specification.
 If the switching time cannot be achieved with the specified control voltage,
a high voltage “boost” supply is used during the switching cycle which, to
increase the voltage per turn, results in faster switching.
 This increases the complexity, and consequently the cost of the driver.
25

26. SELECTION CRITERIA FOR DIGITAL
PHASE SHIFTERS
Twin-Toroid
(S-V
Bands)
Dual-Mode
(S-V Bands)
PIN Diode
(L-Ku
Bands)
GaAs FET
(L-V
Bands)
Geometry Waveguide Waveguide Hybrid MIC Monolithic
Reciprocal/
Non reciprocal
Non
reciprocal
Reciprocal Reciprocal Reciprocal
Bandwidth 5% - 30% 5% - 10% 10% - 20% Octave
Insertion
loss(dB)
0.5-1.0-1.6
(S-Ka-V)
0.5-0.9-1.5
(S-Ka-V)
0.5-2
(L-Ku)
5-12
Switching
time(µs)
1-1-5
(V-Ka-S)
20-30-150
(V-Ka-S)
<1 0.001
Switching
power/energy
25-30-
150µJ
(V-Ka-S)
100-150-1000µJ
(V-Ka-S)
0.1-5 W Negligible
FERRITE PHASE SHIFTERS SEMICONDUCTOR
PHASE SHIFTERS
26

27. Contd…
Twin-
Toroid
(S-V
Bands)
Dual-Mode
(S-V
Bands)
PIN Diode
(L-Ku Bands)
GaAs FET
(L-V Bands)
Peak Power 1-100 kW
(Ka-S)
1-40 kW
(Ka-S)
kW (pulse width
dependent)
W
Average Power 1 kW
(S- band)
500 W
(S- Band)
W mW
Temperature
Sensitivity
0.5º-3º /ºC
Typical
0.5º-3º /ºC
Typical
Negligible --
Insertion phase
trimming for
10% tolerance
Usually
required
Usually
required
Not
necessary
Not
necessary
Radiation
hardness
Excellent Excellent Poor --
Weight 1-4 oz
(Ka-L)
1-4 oz
(Ka-L)
0.5-1 oz
(Ku-L)
<0.1 oz
FERRITE PHASE
SHIFTERS
SEMICONDUCTOR PHASE
SHIFTERS
27

28. FERRITE PHASE SHIFTER 28

29. APPLICATIONS
 Used in a variety of communication and radar systems.
 Microwave instrumentation and measurement systems.
 In industrial applications.
 Remote Control Operation.
 High Speed Phase Modulation.
 Aircraft ,Spacecraft .
 Defence System.
29

30. CONCLUSION
 Phased array radars are used for inertia less scanning and tracking. They
as well can be used for multi target tracking.
 Phased arrays can also be used for air traffic control at the airports.
 Other than defense applications, phase shifters are finding their place in
routine life.
 An American company is working on a project where phased arrays are
used for finding the blind stops on road while driving.
 With such high tech commercial application, driving on road will be
safer.
 The phase shifter technology for phased arrays has no limitation either
in defense applications or in our daily life.
30

31. Thank You
31