Dipole antenna factors below 80 MHz

[Bob Sykes]

     Greetings,
     
     When making field strength measurements below 80 MHz, CISPR 22 
     says to tune the antenna to the 80 MHz resonant length.  Should 
     the antenna be calibrated at these frequencies with the 80MHz 
     resonant length?  Or does one use the antenna factors that were 
     presumably derived using the actual resonant length?
     
     I can find no guidance in published standards on this subject.
     
     Thanks in advance,
     Bob Sykes
     EMC Engineer
     Gilbarco Inc.
     bob_sy...@gilbarco.com