‰  NOW 30 WPM  ‰  a TEXT IS FROM DECEMBER 2013 QST  PAGE 49‰

TIGHTLY COUPLED SO THAT THE CURRENTS ARE EQUAL AND IN OPPOSITE DIRECTIONS.
THAT MEANS THE SAME CURRENT SHOULD FLOW ON THE INSIDE OF THE COAX SHIELD
AND THE CONDUCTOR OF THE LADDER LINE TO WHICH THE SHIELD IS CONNECTED.  IF
ANY OF THE CURRENT ESCAPED ON THE OUTSIDE OF THE COAX FEED LINE AS COMMON
MODE CURRENT, THEN THE BALANCED CURRENT RULE WOULD BE VIOLATED, UPSETTING
THE IMPEDANCE PRESENTED AT THE JUNCTION OF THE TWO FEED LINES.  WHILE THE
COUPLING OF THE TWO CONDUCTORS IN THE FEED LINE SHOULD BE SUFFICIENT TO
GUARANTEE BALANCED CURRENTS IN EACH, ITS A GOOD IDEA TO RAISE THE IMPEDANCE
OF THE COMMON MODE CURRENT PATH, ESPECIALLY BECAUSE YOU DONT KNOW THE
IMPEDANCE OF THAT PATH.  COMMONMODE CURRENT ON FEED LINES CAN CAUSE THE
ANTENNA SYSTEM TO BEHAVE UNPREDICTABLY.  THERE IS ANOTHER REASON TO ADD
SOME COMMON MODE IMPEDANCE TO THE FEED LINE PRESERVING THE SYMMETRY OF THE
ANTENNA SYSTEM.  WITH A BALANCED ANTENNA SUCH AS A DIPOLE OR EDZ,
DECOUPLING OF THE FEED LINES COMMONMODE CURRENT PATH FROM THE ANTENNAS
RADIATED FIELD IS ALSO IMPORTANT, AS EXPLAINED IN W7ELS ARTICLE.  SINCE
COMMON MODE CHOKES ARE DIFFICULT TO CREATE FOR LADDER LINE, I ORIENTED THAT
‰  END OF 30 WPM TEXT  ‰  QST DE W1AW  ƒ