Here is an interesting model that I did in Eznec 
of a end fed top loaded vertical antenna. Eznec 
has no trouble accurately modeling this type of 
antenna so the data presented easily translates 
accurately to a real world antenna of this configuration. 

Anyone who has a licensed copy of Eznec can view 
this antenna file it is located in the file section 
of the EH antenna user group on Yahoo look for file name
End fed top loaded vertical antenna.EZ .


The overall length of this vertical is 25ft. the antenna 
is designed to operate on 14.160Mhz this makes the electrical 
length of the antenna 3/8 wavelength long. The feedpoint 
is located 1.29ft. down from the top of the antenna or another 
way to say it is 5% from one end.

Below is the performance data

Overall length of this vertical is 25ft
Top 2.58ft. of the antenna has a cylinder diameter of 2.9 inches
Below this point the antenna is made of 12 gauge wire 2.053mm
or 0.0808 inch diameter

Frequency of operation 14.160Mhz
loading coil inductance=9.45uH
The antenna is Q= 21.02
calculated total capacitance 13.36pf
feedpoint impedance=40 Ohms
Gain=2.36 dBi modeled over average ground
Calculated 2:1 VSWR= 300Khz
Instantaneous bandwidth= 673.67Khz
841.03 Ohms of reactance