In article ,
Ian Jackson wrote:

I understand that my 2m 5/8 mobile antenna (on a magmount) is
essentially electrically a 6/8 (ie a 3/4 wave - hence a good match). The
actual whip is around 5/8, and the other 1/8 is the 3-turn spring steel
'loading' coil at the bottom end.

Again my understanding is that a 5/8 gives the maximum broadside gain (a
tiddly bit more oomph than a 1/2 wave), and if you make the antenna
longer, the predominant broadside lobe collapses, and most of radiation
moves to the higher angle lobe.

I read somewhere that the maximum gain toward the horizon, was obtained
with a 0.58 wavelength vertical element rather than 5/8 (0.625).

The advantage of a 5/8 antenna with a flat ground plane, is that its
impedance is capacitive with a 50 Ohm resistive component. A small
inductor (loading coil) cancels the capacitance.

Fred
K4DII