1. Dr. S. Cruz-Pol, INEL 4152-Electromagnetics
Polarization:
Why do we care??
Antenna applications –
Antenna can only TX or RX a polarization it is designed to support. Straight wires, square waveguides, and similar rectangular systems support linear waves (polarized in one direction, often) Round waveguides, helical or flat spiral antennas produce circular or elliptical waves.
Remote Sensing and Radar Applications –
Many targets will reflect or absorb EM waves differently for different polarizations. Using multiple polarizations can give different information and improve results.
Absorption applications –
Human body, for instance, will absorb waves with E oriented from head to toe better than side-to-side, esp. in grounded cases. Also, the frequency at which maximum absorption occurs is different for these two polarizations. This has ramifications in safety guidelines and studies.
Cruz-Pol,ECE Dept. UPRM
Electrical Engineering, UPRM

2. Dr. S. Cruz-Pol, INEL 4152-Electromagnetics
Polarization
In general, plane wave has 2 components; in x & y
And y-component might be out of phase wrt to x-component, d is the phase difference between x and y. x y Ey Ex y x
Front View
Cruz-Pol,ECE Dept. UPRM
Electrical Engineering, UPRM

3. Dr. S. Cruz-Pol, INEL 4152-Electromagnetics
Several Cases
Linear polarization: d=dy-dx =0o or ±180on
Circular polarization: dy-dx =±90o & Eox=Eoy
Elliptical polarization: dy-dx=±90o & Eox≠Eoy, or d=≠0o or ≠180on even if Eox=Eoy
Unpolarized- natural radiation
Cruz-Pol,ECE Dept. UPRM
Electrical Engineering, UPRM

4. Dr. S. Cruz-Pol, INEL 4152-Electromagnetics
Linear polarization
Front View
d =0
@z=0 in time domain x y Ey Ex
Back View: y x
Cruz-Pol,ECE Dept. UPRM
Electrical Engineering, UPRM

5. Circular polarization
Dr. S. Cruz-Pol, INEL 4152-Electromagnetics
Circular polarization
Both components have same amplitude Eox=Eoy,
d =d y-d x= -90o = Right circular polarized (RCP)
d =+90o = LCP
Cruz-Pol,ECE Dept. UPRM
Electrical Engineering, UPRM

6. Elliptical polarization
Dr. S. Cruz-Pol, INEL 4152-Electromagnetics
Elliptical polarization
X and Y components have different amplitudes Eox≠Eoy, and d =±90o
Or d ≠±90o and Eox=Eoy,
Cruz-Pol,ECE Dept. UPRM
Electrical Engineering, UPRM

7. Parámetros de la elipse
Dr. S. Cruz-Pol, INEL 4152-Electromagnetics
Parámetros de la elipse y
Eyo a b o x
Eyo
Cruz-Pol,ECE Dept. UPRM
Electrical Engineering, UPRM

8. Polarization Loss Factor PLF
Dr. S. Cruz-Pol, INEL 4152-Electromagnetics
Polarization Loss Factor PLF
Cruz-Pol,ECE Dept. UPRM
Electrical Engineering, UPRM

9. Poincaré Sphere Plots any possible state of polarization
Cruz-Pol,ECE Dept. UPRM

10. Cruz-Pol,ECE Dept. UPRM