Quadripole
Antenna System
The quadripole antenna system is an extension of the Active Dipole
described
elsewhere, in fact it is
essentially two of the these with the elements mounted at right angles
to one another. These each drive one pair of the CAT5 lines
which connect to a 'Shack Board' at the operating position while power
for the assembly comes up the CAT5 in the same manner as for a single
Active Dipole The inputs of the preamplifier connect to
nominally 1m long monopoles to create an orthogonal antenna system.
Although the Active Dipole described elsewhere, was originally
targeted at obtaining the lowest broadband noise floor compared to the
ITU 'quiet rural' data, it performs as an effective probe. It is a small
linearly polarized coupling mechanism to incoming RF energy. By putting
two of these antennas orthogonal two each other it is possible to
synthesize other polarizations, namely Vertical, Horizontal, Right Hand
Circular and Left Hand CIrcular through either DSP or analog
means. This ability not only allows for measurement of the O
and X waves which are propagated by the ionosphere but also allows
effective beam forming for nulling of unwanted signals and noise. The
Quadripole Antenna System is therefore useful for measuring aspects of
ionospheric propagation as well as adding selectivity to incoming
communications to enhance signal-to-noise ratio. In some situations this
enhancement may be profound.