[Mobile-Portable] hamstick vs 102" whip

[K7fe@aol.com]

Jeff,
Any antenna with a large coil on the bottom for 10 meter Mobil is definitely 
not a 5/8 wave.  A quick (but not terribly accurate evaluation) method as 
follows:  a 5/8 wave antenna is 5/8 of 10 meters or 5/8=(converting to decimal) 
0.62.  0.62x10m is 6.2 meters.  Since a meter is about 3 feet (39.37 inches) 
then 6.2 meters x 3 feet = 18.6 feet long.  So a 5/8 wave antenna on 10 meters 
would be about 18.6 feet long.  Anything shorter cannot be a 5/8 wave antenna on 
that band.  Nor can it be a 1/4 wave, because a 1/4 wave antenna does not 
require a base loading coil.  Using the same analogy as above you can see that a 
1/4 wave antenna on 10 meters must be approximately 2.5 meters long or about 
7.5 feet in height.  

The exact length in feet of a 1/4 wavelength antenna can more accurately be 
found by using the following formula:

1/4 wave length in feet = 234 divided by the frequency in megahertz

Sample:  1/4 at 28.350 MHz = 234/28.350 = 8.25 feet (or 99 inches)
     Then a 5/8 wave would actually be 20.62 feet

Shorter antenna's than these would be considered "loaded" antennas and less 
efficent than full size antennas.  In practice many of us use loaded antennas
because the fullsize just won't fit.  Say you mounted a a 1/4 wave antenna 
for 40 meters on you car. That would be 33 feet tall.  Sorry but that antenna 
won't clear the freeway under pass. Hi Hi

Specmanship games and outright lies are often found in antenna manufacture's 
"claims" for antenna specifications.  Antenna "gain" measurements are the most 
abused.  Be cautious and good luck.  

73,
Terry, K7FE  


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