1. Novel Semiconductor Phase Shifters EE Department. KFUPM IEEE-TEM 2000

2. 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. 1. LOW LOSS, ACCURATE phase shift 2.

3. Review of magnetized ferrite phase shifters: When magnetized, the magnetic moments of spinning electrons starts to rotate around the axis of H o, until unidirectional alignment. Direction & frequency of rotation depends on H o. Assume the direction is same as -CP wave 1Damping LOSS 2 CW and CCW 3 -CP; until damping losses stop 1Damping LOSS 2 CW and CCW 3 -CP; until damping losses stop Propagating EM wave interacts and causes aligned magnetic moments to restart rotating.

4. Circularly polarized modes are fundamental for EM wave propagation in biased ferrites. So, interaction between ferrite magnetic moments ( in -CP direction ) and magnetic field component of EM wave (  to H o ) results : =›Accelerated -CP component of mag. field. =›Retarded +CP component of magnetic field. So, two CP’s are rotated by different angles. Consequently, incident LP wave is rotated. 1. 2. M. field is  Ho 3. See fig 1. 2. M. field is  Ho 3. See fig

5. Increasing H o or thickness of the phase phase shift section, increases the phase-shift The direction of phase shift depends on the direction of H o and not in the direction of propagating EM wave => nonreciprocity. 1.rotation of LP 2. Until saturation. 45+45=90 1.rotation of LP 2. Until saturation. 45+45=90

6. 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 Maxwell’s equations.

7. where K o 2 =  2  o  o,  ef f = (  2 -  2 )/ , R=radius and C.E. of Ferrite filled circular wave-guide :

8. YIG G 113:M S =140 KA/m;  r =15.9; B r =1277 G;R=5

10.  eff ={  2 H in 2 -f 2 +2  2 H in M+(  M) 2 } / {  2 H in 2 -f 2 +  2 H in M}

11. Yig G113: M S =140 KA/m;  r =15.9; B r =1277 G;R=5

12. Phase shift per unit length of ferrite (R= mm)

13. 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, H o (and thickness) Semiconductor phase shifters : nonreciprocal

14. According to drude model, the gyroelectric properties of semiconductor is described by;

15. where K o 2 =  2  o  o,  r = dielectric constant, radius R C.E. of semiconductor circular wave- guide :

16.  -f plot of magnetised semiconductor at H o =150 KA/m,  r =16, N=1e18 m -3, m * /m e =0.014, R=1mm

17. Phase shift per unit length of semiconductor (R=1mm)

19. For  r =16, N=1e18 m -3, m * /m e =0.014, R=1mm

20. For  r =12, N=1e16 m -3, m * /m e =0.067, R=1mm

21. Conclusion: Phase shift per unit length is observed for a circular YIG G113 ferrite phaser of 5 mm in radius and magnetized by H o = 0.5 mT Phase shift per unit length is plotted for a magnetized InSb semiconductor phaser of 1mm radius and magnetized by H o =0.19mT 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.