Apparatus for dual-band antenna and communications tower comprising such apparatus are provided. The apparatus comprises a first part (202) comprising first and second propagation paths configured to selectively propagate signals of a first frequency with either a first polarization state or a second polarization state, a transition part (204) rotatable between first and second transition positions to selectively propagate signals of a second frequency along the second signal path with the first polarisation state when in the first transition position and with the second polarisation state when in the second transition position and a rotator part rotatable between first and second rotator positions. Wherein, the rotator part is configured to orientate the polarisation of signals in the second signal path in order to couple the second signal path to an interface, and allow propagation of signals in the first signal path in either the first or second rotator positions.

A polarizer including an antenna connected to a waveguide. The waveguide including a broad wall having a cross-slot in communication with at least one port.

An apparatus and method for orthogonal rotation of a radiation E-field polarization rely on a radiating element including an offset-ridge waveguide and a single-mode first ridge waveguide functionally adjacent to the offset-ridge waveguide.

Microwave antenna systems include a parabolic reflector antenna and a dual-band feed assembly. The dual-band feed assembly includes a coaxial waveguide structure and a sub-reflector. The coaxial waveguide structure includes a central waveguide and an outer waveguide that circumferentially surrounds the central waveguide. The sub-reflector is mounted proximate the distal end of the coaxial waveguide structure.

Apparatus is provided to allow the reception and/or transmission of data signals at two different frequency bands. The apparatus includes a waveguide (4) which has a first section (6) of larger cross sectional area for receiving and/or transmitting the lower frequency band signals, and a reducing section (8) which leads to a section with a reduced cross sectional area in comparison to the first section (6) and this allows the receipt of the higher frequency band signals. In one embodiment sections of the waveguide can be rotated to allow the apparatus to be adjusted to any particular orientation to suit the particular circular polarity transmission type at the location at which the apparatus is provided at that time.

In one example an apparatus is provided. The apparatus includes a low frequency radiator, a high frequency radiator, a high frequency waveguide that carries high frequency bands to the high frequency radiator, a low frequency coaxial waveguide coupled to the high frequency waveguide in a coaxial structure, wherein the low frequency coaxial waveguide carries low frequency bands to the low frequency radiator and a low frequency combiner in communication with the low frequency coaxial waveguide, wherein the low frequency combiner comprises a circular low frequency waveguide and air dielectric transmission lines formed by air channels formed above and below a plurality of printed circuits in a metal housing.

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.

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 comprising 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 said 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 said type of polarization and in the first frequency range to the third waveguide.

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 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.