Mounting        Gain when fed for different polarisations
  point       Vertical       45 degrees     Horizontal
  (mm)         (dBi)            (dBi)          (dBi)  
  3300        21.4410         22.0621         22.4189
  3350        21.8295         22.1861         22.4361
  3400        22.0860         22.2881         22.4526
  3450        22.2532         22.3634         22.4622
  3500        22.3537         22.4118         22.4664
  3550        22.3906         22.4287         22.4643
  3600        22.3650         22.4140         22.4580
  3650        22.2785         22.3714         22.4485
  3700        22.1346         22.3080         22.4379
  3750        21.9326         22.2301         22.4275
  3800        21.6655         22.1423         22.4184
  3850        21.3139         22.0449         22.4106
  3900        20.8614         21.9391         22.4035
  3950        20.3304         21.8335         22.3916
  4000        19.4941         21.6991         22.3328
  4050        20.2378         21.7954         22.3947
  4100        20.5947         21.8578         22.3991
  None        22.5375         22.4652         22.3995
Free space    22.5388         22.5360         22.5335     



None is with boom tube but without mounting tube.
Free space is with elements only, neither boom tube nor 
mounting tube.