I really do like this site. Most users will only react when their own interests are touched. And there is so much fantasy around here.
Well, the length of the antennae corresponded with the frequency range of the radio. For ultra short wave band of the Fu 5 radio set (as used by German tanks) antennae with 1/4 wave length was developed. This was the 2 m Stabantenne (2 m rod antenna). It was also being used by the Sturmgeschuetze with their Fu 16 working at slightly longer waves. Their antenna bases contained adaptor inductors to accommodate the antenna to their Fu 16 radio set.
German long wave radio sets such as those of the command tanks using Fu 12 or Fu 8 radio sets needed frame aerials, or later the less conspicious star antennae. They normally had an additional Fu 5 with 2 m antenna to communicate with normal tanks.
The Fliegerverbindungsoffiziere (ground to air liasion officers) using specialized command tanks used the Fu 7 radio set. This required another antenna, the 1,4 m Stabantenne. The range of this radio set was 50 km against airplanes flying at 500 m altitude and 6 - 10 km against low flying airplanes. The range of this antenna could be enhanced by 20 % by extensions - long rods, resulting in a 4 m long antenna.
The 1,4 m antenna was used with the Fu sprech f radio, too. This radio set was used by APC halftracks, recce armored cars and AT SP guns. For obtaining longer ranges this radio set could be used with 2 m Stabantenne, too.
Please understand that there were many exeptions from this ruel. Why? I don´t know...
Problem solved, at least a bit?