Total posts : 45366
I will admit that I had some difficulty understanding the point in your last post because your argument seems to me to be rather abstract.
I will try to reduce your argument into its elements to understand it better. You seem to, first of all, call for a separation between the antenna and its propagation environment. For the case of the half-wave dipole, this is conceptually easy. There is the dipole (the thing in itself) with its characteristic, or inherent (intrinsic) properties. It is contained in empty, three-dimensional, space extending in all directions to infinity.
It’s a little difficult to similarly separate the “thing in itself” and its operational environment (because they appear inseparable) if one is talking about the vertical monopole above an ideal ground plane. The ground plane, which extends to infinity, is an integral component of the antenna. Without the ground plane, the antenna would not exist. The operational environment is semi-infinite free space with a boundary at the ground plane.
You also speak of “obstructions” on the operational environment, as if they should be considered separately from the antenna. Suppose the obstructions are warious other vertical monopoles on the ground plane. Such monopoles, if close enough to the powered monopole (and big emough) would affect the gain in some directions. These monopoles are actually not separate from the “antenna,” but parts of a larger composite antenna.
In the situation discussed here, there are no pesky obstructions to complicate the problem, but only a simple, infinite, ground plane. The ground plane itself is the “obstruction” you speak of. You say that reflections from the ground plane add 3 dB to the “intrinsic” radiation from the monopole. Without the ground plane and its reflections, however, there would only be an end-fed 1/4 wave monopole with a voltage source with no return path for the displacement current from the monopole. In other words, in the absence of the ground plane, there would be no radiating antenna at all.
For this reason, Rich, I consider your argument about an “intrinsic gain” to be unpersuasive.
The theoretical and experimental fact is that the gain of the quarter-wave monopole above an ideal ground plane is 3 dB greater than the gain of the half-wave dipole.