[opendtv] Re: Circular, elliptical antenna polarization improves mobile DTV reception reliability

"True" CP with a true CP receive antenna has an advantage over a horizontally 
polarized signal when in high multipath environments.  When a CW CP signal 
bounces off of a hard reflector (such as a building) it becomes CCW polarized, 
and is rejected by the CW polarized receive antenna.  The direct path maintains 
its CW polarization and is accepted by the CW polarized receive antenna.

The advantage of CP, dual polarization, elliptical polarization, or however you 
wish to categorize it, in a mobile environment is simply that the receive 
antenna is rarely horizontally oriented.  Therefore, if there is a vertical 
component to the broadcast signal, there is more signal for a vertically 
oriented antenna to receive.

John
  ----- Original Message ----- 
  From: Mark Aitken 
  To: opendtv@xxxxxxxxxxxxx 
  Sent: Wednesday, April 27, 2011 8:47 PM
  Subject: [opendtv] Re: Circular, elliptical antenna polarization improves 
mobile DTV reception reliability


  Dale, correct to both of your points. As to "advantage" of CW or CCW true 
circular...only needed to provide isolation or discrimination from opposing 
rotational emissions...used in space activities for example for DTTH satellite.

  Regards,
  Mark 

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