MHz center frequency fC
mm radiator diameter d
factor V° Radiator
factor V1° Tube ( Transmission Part + Stub )
factor V2° ChassisPart Height ( Stub )
mm tube diameter D°
Input V° Confirmed				.
Input V1° Confirmed				.
Input V2° Confirmed				.
Radiator Length	mm			(300/f).500
Radiator Length V°	mm			(300/f).500.V
Advised Total Length	mm			(300/f).1200.V
Tube Length	mm			(300/f).250.V
Tube Length V1°	mm			(300/f).250.V
'Schlankheitsgrad' S°				(300/f)/d
ChassisPart Height	mm			14500/f
ChassisPart Height V2°	mm			(14500/f).V
Advised Tube Diameter D	mm			min<Zo<max
Tube Diameter D Z 50	mm			Zo = 50 Ohm
Diameter Dmin	mm			D=d.3
Diameter Dmax	mm			D=d.4
Za Radiator	Ohm			TETECH
Q Quality				TETECH
Bswr2 BandWidth	MHz			TETECH
Indication Length	mm			TETECH
Zo Transmission Part°	Ohm			138.log(D/d)

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

Important ! Recommended Radiator Diameters :

A 0145 Mc 10 mm

B 0435 Mc 6 mm

C 1280 Mc 2 mm

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 can be between 1 : 2 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 values : 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 0.96 disappears, and then click the Calculate Button. A warning comes up : "A correct input value is between 0.9 and 1.0". Now click OK.

4 - °( A ) 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 = 2mm, factor V = 0.96 => 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 - °Type the tube diameter to find Zo Transmission Part, it has been calculated apart.

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