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Circular Polorization with Horn Feeds


Figure 1: Circular polarisation by dual feeding

Circular polarization in a horn is created with a quadrature hybrid causing 90 degree phase difference between signal components before signal is applied to horn. Signal is injected by means of separate probes in space quadrature.


Figure 2: Layered polarizer

Passing a linearly polarized signal through a layered polarizer can achieve circular polarization. The polarizer is inclined at 45° so that one component of signal passes through unhindered while the other component undergoes propagation delay.

This method of changig the polarization is used by some Cassegrain- antennae.

Coax to waveguide
transition and input
inclined at 45°

Transition to
orthogonal orientation
and delaying of one field-component

Figure 3: Changing of polarization in a waveguide

Another method for circular polarization in horn antennas is achieved by injecting the input at a 45° angle to the horn's orientation. A combination of methods is then used to delay the selected orthogonal component.


Figure 4: transition from a waveguide with rectangle cross-cut to a round waveguide feeding a Scalar Horn


Figure 4: transition from a waveguide with rectangle cross-cut to a round waveguide feeding a Scalar Horn