‰ NOW 40 WPM ‰ YOU DRILL THROUGH BOTH SIDES OF THE TUBING IN ONE PASS, SO THAT THE WIRE WONT BIND AS YOU PUSH IT THROUGH. THE FEED POINT ASSEMBLY I AM A STRONG BELIEVER IN KEEPING MECHANICAL STRESS OFF ANTENNA CONNECTIONS. I SELECTED A SHORT LENGTH OF SOLID NOT FOAM POLYETHYLENE DIELECTRIC RG 58 COAX FOR THE FEED ARRANGEMENT, BECAUSE IT DID NOT HAVE THE BENDING RADIUS RESTRICTIONS OF FOAM COAX. THIS ALLOWED THE CLAMPING ARRANGEMENT SHOWN IN FIGURE 7, WHICH TAKES THE FEED LINE STRESS, AS WEL AN EASY TO MAKE THREE BAND DIPOLE FOR ARRL FIELD DAY MAKE THIS COUPLED RESONATOR, THREE BAND DIPOLE FOR PORTABLE OR HOME STATION USE. JOEL R. HALLAS, W1ZR ONE OF MY LOCAL CLUBS, THE GREATER FAIRFIELD AMATEUR RADIO ASSOCIATION, WAS PREPARING A TWO TRANSMITTER ARRL FIELD DAY DEPLOYMENT THEIR FIRST AFTER A NUMBER OF YEARS. THEY REQUESTED MY ASSISTANCE IN ANTENNA SELECTION. THEY HAD DECIDED TO HAVE ONE STATION ON 80 AND 40 METERS, PHONE AND CW, AND THE OTHER ON 20, 15, AND 10 IN BOTH MODES. CHOOSING AN ANTENNA IN AN EFFORT TO KEEP IT SIMPLE AND STRAIGHTFORWARD, I SUGGESTED HALF WAVE DIPOLES ON EACH BAND. FROM THE NORTHEAST, A HALF WAVE DIPOLE PATTERN, IF BROADSIDE TO THE SOUTHWEST, CAN PROVIDE REASONABLE COVERAGE OVER MUCH OF NORTH AMERICA. BECAUSE THE CLUB PRESIDENT, BRUCE MOORE, N1ZU, HAD LOTS OF WINDOW LINE ON HAND, THE CHOICE FOR 80 AND 40 METERS WAS EASY A SKELETON SLEEVE OR COUPLED RESONATOR, TWO BAND DIPOLE MADE FROM WINDOW LINE, AS DESCRIBED IN A QST ARTICLE. IT WOULD HAVE ALSO MADE THE CHOICE FOR THE 20, 15, AND 10 METER ANTENNA EASY, IF ONLY THERE WERE SUCH A THING AS THREE WIRE WINDOW LINE. I CONSIDERED A NUMBER OF OTHER POSSIBILITIES, BUT KEPT COMING BACK TO THE COUPLED RESONATOR IDEA. IT HAS ABOUT THE SAME PIECES AS A FAN DIPOLE, BUT IS MORE COMPACT, LESS FUSSY ON TUNING, AND HAS BEEN A GOOD PERFORMER. OTHER POTENTIAL CANDIDATES INCLUDE A FAN DIPOLE, A CENTER FED ZEPP AND A TUNER, OR A THREE BAND TRAP DIPOLE. ALL COULD WORK, BUT THE ZEPP REQUIRES A WIDE RANGE TUNER AND ASSOCIATED OPERATING COMPLICATIONS. IT ALSO HAS A NARROWER PATTERN ON THE HIGHER BANDS. THE TRAP DIPOLE REQUIRES ADDITIONAL COST AND CONSTRUCTION COMPLEXITY TO MAKE AND TEST THE TRAPS. THE THREE BAND COUPLED RESONATOR DIPOLE I MODELED A COUPLED RESONATOR USING PARALLEL WIRES THAT COULD BE HELD AT THE APPROPRIATE SPACING BY INSULATING SPACERS, AND IT CAME OUT VERY WELL, AT LEAST ON THE MODEL. THE FINAL DIMENSIONS OF BOTH THE WIRES AND SPACERS ARE SHOWN IN FIGURE 1. THE EZNEC MODELED SWR OF THE ANTENNA ON EACH BAND, INCLUDING THE EFFECT OF 75 FEET OF RG 8X COAX, IS SHOWN IN FIGURES 2 4. THE MODEL ASSUMED A TYPICAL FIELD DAY HEIGHT OF 30 FEET ABOVE MEDIUM GROUND CONDUCTIVITY 0R005 S/M, RELATIVE DIELECTRIC CONSTANT OF 13. THE TUNING DOESNT CHANGE MUCH GOING 10 FEET EITHER WAY. DESIGN TO PERFORMANCE FOR A COUPLED RESONATOR TO WORK AS DESIRED, THE FEED MUST BE CONNECTED TO THE LOWEST FREQUENCY HALF WAVE, FED JUST LIKE A SINGLE BAND DIPOLE. THE OTHER TWO HALF WAVES HAVE NO DIRECT CONNECTION THEY ARE ‰ END OF 40 WPM TEXT ‰ QST DE W1AW ƒ