Quadripole
Antenna System
The quadripole antenna system is an extension of the Active Dipole
described elsewhere, in fact it is essentially two of the same
high impedance preamplifiers used for that antenna. These each drive
one of the two 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 the 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
targetted 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
Quaripole Antenna System is therefore useful for measuring aspects of
ionospheric propagation as well as adding selectivity to incoming
communications to reject or enhance signal-to-noise ratio. In some
situations this enhancement may be profound.