Novel Semiconductor Phase Shifters

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Novel Semiconductor Phase Shifters
Sheikh Sharif Iqbal, PhD Mahmoud Dawoud, PhD

• EE Department.
• KFUPM

IEEE-TEM 2000
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• Introduction
• The gyromagnetic properties of magnetized ferrite
  is widely used for phase shift section.
• Due to its frequency limitations and high cost,
  gyroelectric properties of magnetized
  semiconductors are exploted here for designing
  millimeter wave phase shifters.

1. LOW LOSS, ACCURATE phase shift 2.
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• Review of magnetized ferrite phase shifters
• When magnetized, the magnetic moments of
  spinning electrons starts to rotate around the
  axis of Ho, until unidirectional alignment.
• Direction frequency of rotation depends on Ho.
  Assume the direction is same as -CP wave

1Damping LOSS 2 CW and CCW 3 -CP until
damping losses stop

• Propagating EM wave interacts and causes aligned
  magnetic moments to restart rotating.

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• Circularly polarized modes are fundamental for EM
  wave propagation in biased ferrites.

1. 2. M. field is ? Ho 3. See fig

• So, interaction between ferrite magnetic moments
  (in -CP direction) and magnetic field component
  of EM wave (? to Ho) results Accelerated
  -CP component of mag. field. Retarded CP
  component of magnetic field.
• So, two CPs are rotated by different angles.
  Consequently, incident LP wave is rotated.

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1.rotation of LP 2. Until saturation.
454590

• Increasing Ho or thickness of the phase phase
  shift section, increases the phase-shift
• The direction of phase shift depends on the
  direction of Ho and not in the direction of
  propagating EM wave gt nonreciprocity.

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• In ferrites, the anisotropic interaction of the
  magnetic moments and the EM wave is governed by
  its permeability tensor

• Typically, ?r?50-3000 and ?r?10-20.
• EM field components within ferrite are expressed
  by substituting ?r and boundary condition into
  Maxwells equations.

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C.E. of Ferrite filled circular wave-guide

• where Ko2 ?2?o?o , ?ef f (?2-?2)/? , Rradius
  and

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YIG G 113MS140 KA/m?r15.9 Br1277 GR5
YIG G 113
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YIG G 113
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?eff?2Hin2-f22?2HinM(?M)2/?2Hin2-f2?2HinM
YIG G 113
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Yig G113 MS140 KA/m?r15.9 Br1277 GR5
YIG G 113
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Phase shift per unit length of ferrite (R mm)
YIG G 113
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• Magnetized semiconductor phase shifters
• The interaction of Electric field (EM wave) and
  free electrons of biased semiconductor produces
  gyroelectric cyclotron motion (of electrons),
  responsible for phase shift action

• The direction and magnitude of phase shift
  depends on the direction and magnitude of biasing
  magnetic field, Ho (and thickness)
• Semiconductor phase shifters nonreciprocal

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• According to drude model, the gyroelectric
  properties of semiconductor is described by

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C.E. of semiconductor circular wave-guide
where Ko2 ?2?o?o , ?r dielectric constant,
radius R
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?-f plot of magnetised semiconductor at Ho150
KA/m, ?r16, N1e18 m-3, m/me0.014, R1mm
InSb
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Phase shift per unit length of semiconductor
(R1mm)
InSb
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InSb
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For ?r16, N1e18 m-3, m/me0.014, R1mm
InSb
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For ?r12, N1e16 m-3, m/me0.067, R1mm
GaAs
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• Conclusion
• Phase shift per unit length is observed for a
  circular YIG G113 ferrite phaser of 5 mm in
  radius and magnetized by Ho 0.5 mT
• Phase shift per unit length is plotted for a
  magnetized InSb semiconductor phaser of 1mm
  radius and magnetized by Ho0.19mT
• For ferrites, the frequency range of 4.5 to 9 GHz
  was plotted and for semiconductor the frequency
  range of 28 to 32.5 GHz was observed. The phase
  shift is noted to increase with frequency.