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Polarization :

Polarization :. Why do we care?? Antenna applications –

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Polarization :

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  1. 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

  2. x Ex x y Ey y 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. Front View Cruz-Pol,ECE Dept. UPRM

  3. Several Cases • Linear polarization: d=dy-dx =0oor ±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

  4. x Ex x y Ey y Linear polarization Front View • d =0 • @z=0 in time domain Back View: Cruz-Pol,ECE Dept. UPRM

  5. Circular polarization • Both components have same amplitude Eox=Eoy, • d =dy-dx= -90o = Right circular polarized (RCP) • d =+90o = LCP Cruz-Pol,ECE Dept. UPRM

  6. Elliptical polarization • X and Y components have different amplitudes Eox≠Eoy, andd =±90o • Or d≠±90o and Eox=Eoy, Cruz-Pol,ECE Dept. UPRM

  7. Parámetros de la elipse y Eyo a b o x Eyo Cruz-Pol,ECE Dept. UPRM

  8. Polarization Loss Factor PLF Cruz-Pol,ECE Dept. UPRM

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

  10. Cruz-Pol,ECE Dept. UPRM

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