Polarization in Nature, Technology and Radio

1. David Conn VE3KL Polarization in Nature, Technology and Radio 1932 Chevy ? Credits http://www.polarization.com/land/land.html http://www.windows.ucar.edu/tour/link=/earth/images/earth_magneto_image.html&edu=high David Conn VE3KL QCWA Sept 2006

2. Acknowledgements Wild Rose Chapter 151 QCWA QCWA Chapter 70 Members Ken Oelke VE6AFO Graham Ide VE3BYT Clare Fowler VE3NPC Ken Pulfer VE3PU Doug Leach VE3XK David Conn VE3KL QCWA Sept 2006

3. What is Polarization ? David Conn VE3KL QCWA Sept 2006

4. Light and Radio Waves • Composed of Electric Fields, E • E at right angles to direction of propagation • E can be Horizontal, Vertical, Circular.. • Unpolarized…….. The Sun David Conn VE3KL QCWA Sept 2006

5. Why is Polarization Important ? • The Ionosphere and materials change the polarization of Radio Waves • Operation of Lasers, LCD displays, Sun Glasses • Medical research…. Diabetes • Biology .. Insects.. David Conn VE3KL QCWA Sept 2006

6. The Basics … #1[Reflection..Refraction] Standing Wave Region SWR Air Reflected Wave Water Refracted Wave Incoming Plane Wave David Conn VE3KL QCWA Sept 2006

7. The Brewster Angle[E in plane of the Screen] 53 Degrees NO Reflection Like a matched Load SWR = 1:1 Air Water Refracted Wave Incoming Plane Wave of Light David Conn VE3KL QCWA Sept 2006

8. Basics.. #2The Wire Grid Polarizer Horizontal Wires Incoming Unpolarized Light/Radio Wave Vertically Polarized Horizontally Polarized David Conn VE3KL QCWA Sept 2006

9. The Wire Grid Reflector or Transmitter Horizontal Wires Vertically Polarized Wave Circularly Polarized Wave Horizontally Polarized David Conn VE3KL QCWA Sept 2006

10. Examples • Rainbows • Sun Glasses • Liquid Crystal Displays • The Magnetosphere • Four Antennas • Insects David Conn VE3KL QCWA Sept 2006

11. Rainbows Are they Polarized ? David Conn VE3KL QCWA Sept 2006

12. YES…But Why? Horizontal At Top Note the Double Rainbow David Conn VE3KL QCWA Sept 2006

13. Here is Why Unpolarized Light from the Sun Water Droplet Brewster Angle 42 degrees Vertical Polarized perpendicular to the Screen Horizontal David Conn VE3KL QCWA Sept 2006

14. Polarized Sunglasses Transmit Vertically Polarized Light Vertical lost due to Brewster Horizontal lost by Glasses Wire Grid Angle Important Brewster Angle Horizontally Polarized David Conn VE3KL QCWA Sept 2006

15. Liquid Crystals cyanobiphenyl materials 1888 Liquid Crystal Credits http://www.kth.se/fakulteter/TFY/kmf/lcd/lcd~1.htm http://nobelprize.org/educational_games/physics/liquid_crystals/history/ David Conn VE3KL QCWA Sept 2006

16. LCD Display http://nobelprize.org/educational_games/physics/liquid_crystals/history/ David Conn VE3KL QCWA Sept 2006

17. Polarization in the Ionosphere Big Impact on Radio and EME Earth’s Magnetic Field Linear Polarization (45 degrees tilt) Elliptical Polarization 50 MHz Electrons in the Ionosphere 70 Km David Conn VE3KL QCWA Sept 2006

18. Polarization in the Ionosphere Faraday Rotation Horizontal Polarization Input Earth’s Magnetic Field Vertical Polarization Output A Horizontal Dipole will NOT Talk to a Horizontal Dipole. Electrons in the Ionosphere David Conn VE3KL QCWA Sept 2006

19. Some Examples of Circularly PolarizedAntennas • Two Crossed Dipoles …… Basic • Two Crossed Dipoles …… Very simple • The Classic Helix …. Complex • The Skew Planar …. Very Complex David Conn VE3KL QCWA Sept 2006

20. Two Crossed Dipoles Horizontal Antenna LHC λ/4 50 Watts Transmitter 100 Watts Direction of Propagation 50 Watts Vertical Antenna Antennas Fed In-Phase (Details not shown) David Conn VE3KL QCWA Sept 2006

21. A Simple Circularly Polarized Antenna Two crossed dipoles Connected in parallel One LONGER than the other Radiates into the Screen Zin = 50 Ohms David Conn VE3KL QCWA Sept 2006

22. The HelixAntenna • Invented by John Kraus • Used by Amateurs for Satellite Communications • Difficult to Analyze • Relatively High Gain …. 15 dBc David Conn VE3KL QCWA Sept 2006

23. The Helix Antenna David Conn VE3KL QCWA Sept 2006

24. The Skew Planar Antenna 900 MHz Beacon Applications • A Story of its Own • Researched extensively by Graham Ide (VE3BYT) • Omni Directional and Circularly Polarized • First reported in QST 1960’s • Not used again until Graham got interested David Conn VE3KL QCWA Sept 2006

25. The Skew Planar Antenna 70 Cm Beacon Applications VE3BYT David Conn VE3KL QCWA Sept 2006

26. Insects Some Insects have complex polarized eyes http://xray.optics.rochester.edu/workgroups/cml/opt307/spr04/greg/ David Conn VE3KL QCWA Sept 2006

27. Summary • The Concepts and Use of Polarized Signals Span many disciplines • Two Ideas Presented: The Brewster Angle The Wire Grid David Conn VE3KL QCWA Sept 2006

28. VY 73 David David Conn VE3KL QCWA Sept 2006

29. Where to Get More Informationand Credits • http://webphysics.davidson.edu/physlet_resources/dav_optics/Examples/polarization.html • http://en.wikipedia.org/wiki/Liquid_crystal_display • http://www.ngsir.netfirms.com/englishhtm/Lissajous.htm • Fields and Waves in Communication Electronics: Ramo, Whinnery, Van Duzer ; John Wiley, third edition, 1994, ISBN 0-0471-58551-3 David Conn VE3KL QCWA Sept 2006