Antenna orientation and polarization

Question

Suppose a rubber duck antenna with the typical radiation pattern as shown below,

Rubber duck Antenna http://www.l-com.com/copyrighted_images/pattern_hg2405rd.gif

also the manufacture specifies that this monopole has vertical polarization.

If I put the "vertical monopole" in a horizontal orientation, the polarization changes to horizontal?

So the antenna has lineal polarization and the orientation of the antenna will determine if it has horizontal or vertical? Also the radiation pattern will shift from Vertical to Horizontal and vice-versa? Like the monopole antenna what kind of antennas will be affected for this phenomenon.

Also I would like to know if the polarization is affected by obstacles? Like Faraday Rotation in ionosphere that satellite communications needs to overcome.

Answer 1

A monopole antenna is one half of a proper dipole antenna. If you rotated the proper dipole through 90 degrees then the polarization direction follows the rotation. Because a monopole needs a ground plane to operate correctly, rotating it thru 90 degrees creates a bit of a mess mathematically and it becomes a bit unclear how the polarization changes precisely.

This is how a (ground referenced) monopole is "derived" from a free-space dipole (position c in the diagram below): -

This derivation is based on the fact that all lines of electric field along the horizontal centre-line of the dipole are effectively 0V and therefore can be replaced with a central ground-plane (without affecting dipole performance). The implication of this is that the lower half of the centre-ground-planed dipole can be discarded leaving a single monopole on a ground-plane.

The words that accompany this diagram in wiki are: -

Showing the monopole antenna has the same radiation pattern over perfect ground as a dipole in free space with twice the voltage

In other words I believe the basic premise of the question is slightly flawed.