MHz center frequency fC
mm radiator diameter d
factor V °
Radiator Length	mm			(300/f).500.V
Advised Total Length	mm			(300/f).1000.V
Tube Length	mm			(300/f).250.V
'Schlankheitsgrad' S °				(300/f)/d
ChassisPart Height	mm			(300/f).(145/3)
Advised Tube Diameter D	mm
Diameter Dmin	mm			D=d.3
Diameter Dmax	mm			D=d.4

This script calculates the values concerning VHF UHF and SHF SperrTopf Antennas .. Based on the Karl Rothammel and ARRL Antenna Fundamentals :-)

1 - Type the desired center frequency fC in MHz.

2 - Type the desired radiator outer diameter d in mm. You have to know that d : D is between 1 : 3 and 1 : 4. D is the inner diameter of the tube. It is possible to calculate from radiator to tube or from tube to radiator : click here and scroll to VHF UHF SHF spertop.

3 - Type the factor V, if you do not know it, click the input, now the value 0.94 disappears, and then click the Calculate Button.

4 - ( A ) Now, the calculation delivers the so called 'Schlankheitsgrad' ( and already the ChassisPart Height too ). Now you will find easily the V factor, use the diagram above. Click on it.
     ( B ) Type ( the found value, input factor V ) and click the Calculate Button again.

For example : fC = 1280 MHz, d = 6 mm, factor V = 0.94 => you find the correct values. The Advised Total Length is the required length of the inner conductor to attach easily the antenna to a mast.

5 - The Reset System button clears the outputs and sets defaults again.