I thought that vertically polorized antennas were omni directional?
The vertical antenna is omnidirectional, but its signal is vertically polarized, which makes it difficult to communicate using the ground wave with horizontally polarized signals, no matter what direction they are received from.
Omnidirectional refers to the pattern around feedpoint of the antenna.
Polarization refers to whether the Electric portion of the electromagnetic wave is Vertical as referenced to the plane of the Earth, or horizontal.
Two different terms that mean two entirely different things.