Mobile Antenna FS Comparisons

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The hat used in these tests was the DX Engineering Hot Rodz system.

Type Height Base Top Length Hat dia Field Strength Frequency Relative FS  
Reference     -18.5     best tested antenna
Large  air 36" 84" 0 -18.50 7.2 0.00 3"dia #12
Large Air 36' 27" 47" -18.70 7.2 -0.20 3" dia #12 47" hat
Small air 36" 27" 47" -19.90 7.2 -1.40 1.5"dia #16 47" hat
TarHeel 42" 27" 47" -21.00 7.2 -2.50 Tar with 47" dia
TarHeel 43" 84" 0 -21.10 7.2 -2.60 Tar with 7' whip
RM-20 36" 27" 52" -21.20 7.2 -2.70 Hustler RM-20 on 40m
TarHeel 43" 27" 23" -22.00 7.2 -3.50 Tar with 23" dia
             
             
TarHeel 61" 84" 0 -19.80 3.5    
TarHeel 59" 27" 47" -19.70 3.5   47" DXE

 

The most striking things are:

  • The range between the best and worse system was only 3.5dB
  • A large hat at the TOP of the antenna allows considerable shortening with no loss in efficiency
  • For a given height antenna, efficiency is increased with a hat at the top 

Mobile and Loaded Antenna