Mobile Antenna FS Comparisons



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