BEFORE TAKEOFF, THE CREW OF N7647U (UA FLT 663) NOTED CUMULUS CLOUDS & VIRGA IN THE AREA. AT 1327, A DEHAVILLAND DASH 7 CREW RPRTD A 25 KT LOSS OF AIRSPEED, BUT SVRL OTHER ACFT THEN TOOK OFF WITHOUT RPRTG A PROBLEM. DUE TO RADIO CONJESTION,THE CAPTAIN DID NOT QUERY OTHER AIRCREWS, BUT DECIDED TO CLIMB OUT AT V2 PLUS 20. WHEN THE CONTROLLER CLEARED FLT 663 FOR TAKEOFF, HE ADVISED THE CREW OF NUMEROUS WIND SHEARS IN 3 QUADRANTS, BUT USED INCORRECT TERMINOLOGY IN ISSUING THE WIND SHEAR ALERT. DURING TAKEOFF, THE ACFT STRUCK AN ILS LOCALIZER ANTENNA, 1074 FT FROM THE DEPT END OF THE RWY, & DAMAGED THE LOWER FUSELAGE. WHEN UNABLE TO PRESSURIZE THE ACFT, THE CREW RETURNED TO THE ARPT & LANDED. AN INVESTIGATIONREVEALED THE ACFT ENCOUNTERED WIND SHEAR FROM MICROBURST ACTIVITY WHICH REACHED ITS GREATEST ACTIVITY AS FLT 663 WAS TAKING OFF. THE WIND SHEARED FROM AN 8 KT HEADWIND TO 40 TO 56 KTS OVER A 44 SEC PERIOD. THE CREW NOTED A HESITATION WHILE ACCELERATING THRU 120 KTS, THEN AT OR BEYOND VR SPEED OF APRX 141 KTS, THE ACFT MOMENTARILY LOST 20 KTS.