‰  NOW 30 WPM  ‰  TEXT IS FROM SEPTEMBER 2019 QST PAGE 32 ƒ

UP THE 30 AND 15 METER BANDS.  A LESS WELL KNOWN VARIATION IS THE 20 OCFD.
FIGURE 2 DEMONSTRATES THAT THIS DESIGN COVERS SEVEN HAM BANDS BUT CANT BE
EASILY MATCHED ON 17 METERS.  FEED POINT POSITIONING FIRST, WE NEED TO
SELECT A FEED POINT WHOSE POSITION DOESNT CAUSE A HARMONIC OF THE HALF WAVE
RESONANT FREQUENCY TO FALL INSIDE OR TOO CLOSE TO A HAM BAND.  SECOND, WE
MUST MAINTAIN A LOW SWR AT THE HIGHER FREQUENCIES TO AVOID SIGNIFICANT
MISMATCH LOSSES IN THE FEED LINE.  THIRD, THE SWR AT THE TRANSMITTER SHOULD
BE EASILY MATCHED BY AN AUTOTUNER, WHETHER BUILT IN TO THE RADIO OR
AVAILABLE SEPARATELY, OR BY A LOW LOSS MANUAL L C TUNER.  SEVERAL FEED
POINT POSITIONS DELIVER USEFUL RESULTS, BUT FIGURE 3 INDICATES THAT THE 45
FEED POINT IS A GOOD SOLUTION FOR ALL THREE GOALS ON EIGHT OF THE MOST USED
HF AMATEUR BANDS.  THE SWR VALUES SHOWN IN TABLE 1 SHOULD BE EASILY MATCHED
BY EMBEDDED AUTOTUNERS OR COMMERCIALLY AVAILABLE EXTERNAL MATCHING
NETWORKS.  MOVING THE FEED POINT SLIGHTLY TO ONE SIDE OR THE OTHER
REBALANCES THE 40 METER AND 12 METER SWR LEVELS, AS DOES FEEDING THE
ANTENNA IN THE VICINITY OF THE 22R5 FEED POINT, BUT THE 45 FEED POINT MEETS
‰  END OF 30 WPM TEXT  ‰  QST DE W1AW  ƒ