‰  NOW 40 WPM  ‰  TEXT IS FROM JUNE 2014 QST  PAGE 41 ‰
SOME ACTUAL RESISTANCE, ALL THE TRANSMITTER POWER HITS A DEAD END AND
REFLECTS BACK TO THE COAX AND YOUR TRANSCEIVER, GIVING ANTENNA 2 AN
INFINITELY HIGH SWR NOT A GOOD RADIATOR.  THE TWO SIDES OF IMAGINARY THAT
BRINGS US TO THE OPERATOR.  THE OPERATOR TELLS US WHAT TYPE OF REACTANCE
THE ANTENNA HAS.  THE SYMBOL INDICATES AN INDUCTIVE REACTANCE WHILE THE
SYMBOL INDICATES A CAPACITIVE REACTANCE.  YOURE NOT SUPPOSED TO ACTUALLY
USE THEM TO ADD OR SUBTRACT.  IF YOUR AN

300 600 TO WORK PROPERLY WITH A 50 TRANSCEIVER, AN IMPEDANCE TRANSFORMER OR
ANTENNA TUNER IS NEEDED.  THE RADIO ENERGY IS CARRIED BY THE COAX TO THE
ANTENNA.  AGAIN, FOR MAXIMUM POWER TRANSFER, THE ANTENNAS IMPEDANCE MUST BE
50 IF ITS NOT, AND THE ANTENNAS IMPEDANCE IS, SAY, 100, THEN THE TWO ARENT
MATCHED AND PART OF THE POWER FROM THE COAX IS REFLECTED BACK TO THE
TRANSMITTER.  ITS EASIEST TO THINK OF THIS REFLECTED POWER IN TERMS OF
VOLTAGE.  IF THE LINE IS MATCHED, THERE IS NO REFLECTION AND THE VOLTAGE
EVERYWHERE ALONG THE COAX IS THE SAME, WHICH MEANS THAT THE STANDING WAVE
RATIO SWR IS 1 1.  IF THE ANTENNA AND COAX ARE MISMATCHED, THEN PART OF THE
VOLTAGE THAT REACHES THE ANTENNA IS REFLECTED BACK DOWN THE COAX TO THE
TRANSMITTER.  AT THE SAME TIME, THE TRANSMITTER IS STILL DRIVING VOLTAGE
FORWARD TOWARD THE ANTENNA.  WHEN THE FORWARD VOLTAGE WAVE MEETS THE
REFLECTED REVERSE VOLTAGE WAVE THE TWO MIX TOGETHER.  IN SOME PLACES ON THE
COAX THEY ADD AND AT OTHER SPOTS THEY SUBTRACT, CREATING A STANDING WAVE ON
THE COAX.  THE RATIO OF THE HIGHEST AND LOWEST AMPLITUDES OF THE STANDING
WAVE ALONG THE COAX GIVES US THE SWR.  THE GREATER THE MISMATCH, THE HIGHER

THE J FACTOR COMPLEX IMPEDANCE ISNT COMPLICATED.  STEVE SANT ANDREA, AG1YK
WELL, THAT NEW ANTENNA ANALYZER YOU WERE GIVEN FOR CHRISTMAS HAS BEEN
WORKING GREAT.  YOU CAN DIAL IN ANY FREQUENCY AND GET YOUR ANTENNAS SWR TO
MORE DECIMAL PLACES THAN YOU WANT TO KNOW.  YOURE HAPPY WITH YOUR MAIN
ANTENNA THE SWR IS MORE THAN MANAGEABLE ON ANY BAND YOU WANT TO OPERATE.
OKAY, YOU THINK.  NOW WHAT?  HMMM, NEXT ON THE LIST WOULD BE THAT 100 FOOT
TOP BAND DIPOLE I PUT UP IN THE FALL SEE FIGURE 1.  I COULD HAVE SWORN I
CALCULATED THE LENGTHS CORRECTLY, BUT IT PROVED IMPOSSIBLE TO TUNE.  LETS
SEE WHAT THE ANALYZER CAN TELL US.  THE STANDING WAVE NO, NOT THE STADIUM
HALFTIME KIND THIS ONE HAS TO DO WITH GETTING POWER TO YOUR ANTENNA.  THE
FIRST REQUIREMENT FOR GETTING THE STRONGEST SIGNAL OUT ON THE BANDS IS TO
GET THE MOST POWER FROM YOUR FINALS TO YOUR ANTENNA.  A BASIC
CHARACTERISTIC OF ALL ELECTRICAL CIRCUITS AND AN ANTENNA SYSTEM IS JUST ONE
FORM OF ELECTRICAL CIRCUIT IS THAT A TRANSMITTER POWER SOURCE TRANSFERS THE
MOST POWER TO AN ANTENNA POWER LOAD WHEN THE SOURCE AND LOAD HAVE THE SAME
IMPEDANCE.  MODERN TRANSMITTERS HAVE 50 OUTPUT IMPEDANCES.  THIS MATCHES
THE 50 IMPEDANCE OF THE COAX, MAKING FOR MAXIMUM POWER TRANSFER ONTO THE
LINE.  THE SAME MATCHING EFFECT IS TRUE WHEN USING THE VARIOUS TYPES OF
LADDER/WINDOW LINE.  THESE BALANCED LINES HAVE IMPEDANCES THAT RANGE FROM
‰  END OF 40 WPM TEXT  ‰  QST DE W1AW  ƒ