A linear-to-circular polarizer antenna is disclosed. In accordance with embodiments of the invention, the polarizer antenna includes an antenna operable to transmit and receive polarized signals and a linear-to-circular polarizer coupled to the antenna. The polarizer includes a plurality of cascaded elements, waveplates or anisotropic sheets, having biaxial permittivity. Each cascaded element has a principal axis rotated at different angles relative to an adjacent element about a z-axis of a 3-dimensional x, y, z coordinate system, and each element is composed of an artificial anisotropic dielectric. The polarizer further includes impedance matching layers disposed adjacent the cascaded elements.

In one embodiment, a waveguide structure, disposed between a first waveguide port and second and third waveguide ports, is configured to split, in the frequency domain, the first signal into the second and third signals, and/or combine, in the frequency domain, the second and third signals into the first signal. The waveguide structure includes an asymmetric cross-sectional shape defining first and second aperture regions having respective first and second extents, wherein the second extent is less than the first extent. The waveguide structure is arranged relative to the second and third waveguide ports such that the third waveguide port is predominantly adjacent the first aperture region, and the second waveguide port is predominantly adjacent the second aperture region.

A transmitter of a feed network includes first and second branches and an integrated branch line coupler that couples the first and second branches. The integrated branch line coupler includes first and second waveguide reject filters in the first and second branches respectively. The first and second waveguide reject filters include one or more single-sided stubs protruding outwardly from outer faces of the first and second waveguide reject filters. The integrated branch line coupler further includes one or more couplers that are coupled between inner faces of the first and second waveguide reject filters. The transmitter includes a core waveguide that is coupled to the first and second branches. The transmitter receives a linearly polarized signal from an input port of the first or second branches and generates a circularly polarized signal in the core waveguide.

An antenna system includes a reflector, an offset feed horn and a support platform. The reflector has a reflector surface. The reflector and offset feed horn are attached to the support platform. The offset feed horn transmits RF microwave energy toward the reflector surface. The antenna system further includes a turntable which has a single rotation axis. The turntable rotates about the antenna rotation axis. The support platform is attached to the turntable such that the turntable rotates the support platform. The reflector surface has a perturbed paraboloid geometrical shape that reflects most RF microwave energy along a beam peak pointing direction. The reflector surface reflects RF microwave energy towards the earth's surface in such a manner that the reflected RF microwave energy illuminates a narrow strip of the earth's surface from nadir to a point near the earth's horizon with substantially constant intensity. The offset feed horn is oriented and positioned such that it points away from the beam peak pointing direction.

An antenna feed includes a waveguide having a main part in hollow straight cylinder form extending in a direction, a radiating element, comprising ridges extending inwards and several treads along the direction, the number, the heights and the thicknesses of the treads being configured to allow a variation of impedance of the radiating element, a polarizer comprising two inputs separated by an internal leaf extending in the direction, and an output corresponding to the input of the radiating element, the internal leaf comprising several levels configured to transform a circularly polarized electromagnetic field into linear polarization, the polarizer comprising ridges extending inwards, the radiating element and the polarizer being made of a single piece, and disposed end-to-end in the direction, and a third portion comprising a filter, the internal leaf being prolonged in or part all of the third portion, the filter comprising a set of frequency filtration posts disposed inside the third portion and on one and the same surface of the internal leaf, the output of the filter corresponding to one of the two inputs of the polarizer, the third portion further comprising third ridges extending inwards and over all or part of the length of the third portion, the third ridges and the internal leaf being regularly distributed around the perimeter of the third portion; the radiating element, the polarizer and the filter being made of a single piece, preferably produced by an additive manufacturing technique, and the polarizer and the filter being disposed end-to-end in the longitudinal direction.

A septum polarizer according to one embodiment can comprise a waveguide body and a stair-shaped septum, which is arranged in the longitudinal direction inside the waveguide body and divides the waveguide body into two parts, and has stepped parts of different heights so that a higher order mode can be reduced in a preset frequency band. In addition, a septum polarizer according to one embodiment can comprise: a waveguide body having a polygonal cross-section; a stair-shaped septum, which is arranged in the longitudinal direction inside the waveguide body and divides the waveguide body into two parts; and a pleated part arranged on the outer surface of the waveguide body, and

A third coupler (3c) outputs a signal outputted from a first coupler (3a) to an input terminal (8-1) of a second septum polarizer (8b), and outputs a signal outputted from a second coupler (3b) to an input terminal (8-2) of a first septum polarizer (8a).

A method includes receiving, through a vertical polarization port of an orthogonal-mode transducer (OMT), a vertical polarized signal from a vertical polarization diplexer, and receiving, through a horizontal polarization port of the OMT, a horizontal polarized signal from a horizontal polarization diplexer. The method also includes receiving, through a common port of the OMT, a circular polarized signal comprising the vertical and horizontal polarized signals. The common waveguide includes a septum polarizer configured to split or combine between the circular polarized signal, and the vertical polarized signal and the horizontal polarized signal.

A diplexer for an antenna comprises a first waveguide operative in a first frequency range, a second waveguide operative in a second higher frequency range, a third waveguide operative in the first frequency range, a transmission device including at least three electric conductors, in which at least one of (i) or (ii) is met: (i) the transmission device is operative to receive electromagnetic radiations with at least one type of polarization and in the first frequency range from the third waveguide and to transmit electromagnetic radiations with the type of polarization and in the first frequency range to the first waveguide; (ii) the transmission device is operative to receive electromagnetic radiations with at least one type of polarization and in the first frequency range from the first waveguide and to transmit electromagnetic radiations with the type of polarization and in the first frequency range to the third waveguide.

A transmitter of a feed network includes first and second branches and an integrated branch line coupler that couples the first and second branches. The integrated branch line coupler includes first and second waveguide reject filters in the first and second branches respectively. The first and second waveguide reject filters include one or more single-sided stubs protruding outwardly from outer faces of the first and second waveguide reject filters. The integrated branch line coupler further includes one or more couplers that are coupled between inner faces of the first and second waveguide reject filters. The transmitter includes a core waveguide that is coupled to the first and second branches. The transmitter receives a linearly polarized signal from an input port of the first or second branches and generates a circularly polarized signal in the core waveguide.