=  NOW 35 WPM  =  TEXT IS FROM MAY 2024 QST  PAGE 36 =

AND FOR THREE ANTENNAS, THE IMPEDANCE IS ABOUT 17 W.  THE PS 3B PHASING
RELAY UNIT HAS A BROAD BANDWIDTH, HIGH POWER, IMPEDANCE MATCHING TRANSFORMER
THAT TAKES THE LOWER RESISTANCES OF 25 OR 17 W AND MATCHES THEM TO 50 W.  TO
MAINTAIN PROPER PHASING, THE FEED LINES TO EACH ANTENNA SHOULD BE THE SAME
LENGTHS. THE LARGEST ADVANTAGE OF STACKING ANTENNAS IS NOT NECESSARILY THE
ADDITIONAL GAIN, BUT THE ABILITY TO MOVE ANTENNA NULLS SO A DESIRED SIGNAL
DOESNT FALL INTO ONE.  WHILE GAIN MAKES A MARGINAL IMPROVEMENT, MOVING A
NULL CAN MAKE THE DIFFERENCE BETWEEN A BARELY READABLE SIGNAL AND ONE THAT
IS STRONG ENOUGH TO MAKE A RARE DX CONTACT. YOU WILL ALWAYS WANT THE DESIRED
SIGNAL TO BE IN THE MAIN LOBE OF THE ANTENNA RATHER THAN A SIDE LOBE, AND
DEFINITELY NOT IN A DEEP NULL.  A YAGI AT THE TOP OF A 60 FOOT TOWER HAS A
MAIN LOBE THAT IS NOT ALWAYS OPTIMAL FOR THE DESIRED PATH.  THIS IS BECAUSE
THE TOA FOR THE DESIRED SIGNAL IS NOT THE SAME AS THE ANTENNAS MAIN LOBE.  A
SINGLE ANTENNA INSTALLED AT MORE THAN 1 WAVELENGTH ABOVE GROUND HAS SEVERAL
LOW ANGLE LOBES, WITH DEEP NULLS BETWEEN EACH LOBE. THESE NULLS CAN BE MINUS
20 DB OR GREATER.  FROM MY LOCATION IN GEORGIA, AUSTRALIA IS ABOUT 10,000
MILES AWAY, ITALY IS ABOUT 5,000 MILES AWAY, AND SAINT LUCIA IS ABOUT 2,000
MILES AWAY.  THE OPTIMAL TOA IS QUITE DIFFERENT FOR EACH OF THESE LOCATIONS.
FOR A FARAWAY DX STATION, LOWER TOAS ARE THE MOST USEFUL.  FOR CLOSER
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