Abstract: A multi-frequency folded lens antenna structure includes a stack, and the stack includes a polarization-dependent trans-reflector, a dielectric gap, and a multi-frequency twist-reflector; wherein the polarization-dependent trans-reflector is configured to transmit electromagnetic radiation of a first polarization incident from within the stack out of the stack and to reflect electromagnetic radiation of a second, different polarization incident within the stack towards the multi-frequency twist-reflector, and the multi-frequency twist-reflector is configured to selectively change a polarization of the reflected electromagnetic radiation from the second polarization to substantially the first polarization and to direct the electromagnetic radiation of substantially the first polarization, within the stack, towards the polarization-dependent trans-reflector for at least partial transmission out of the stack, wherein the multi-frequency twist-reflector is configured to selectively change the polarization for at

Abstract: An apparatus, for example a multi-band radio frequency antenna system, comprising: a primary reflector, for example a parabolic reflector; and a near-field feed arrangement comprising: a multi-band waveguide feed comprising a first waveguide feed for a first frequency band and a second waveguide feed for a second frequency band separate to the first frequency band, wherein the first waveguide feed and the second waveguide feed are co-axial and have, respectively, a first aperture and a second aperture; and a splashplate located within the near-field of the first waveguide feed, located within the near field of the second waveguide feed and configured as a feed for the primary reflector.

Abstract: A multi-frequency folded lens antenna structure includes a stack, and the stack includes a polarization-dependent trans-reflector, a dielectric gap, and a multi-frequency twist-reflector; wherein the polarization-dependent trans-reflector is configured to transmit electromagnetic radiation of a first polarization incident from within the stack out of the stack and to reflect electromagnetic radiation of a second, different polarization incident within the stack towards the multi-frequency twist-reflector, and the multi-frequency twist-reflector is configured to selectively change a polarization of the reflected electromagnetic radiation from the second polarization to substantially the first polarization and to direct the electromagnetic radiation of substantially the first polarization, within the stack, towards the polarization-dependent trans-reflector for at least partial transmission out of the stack, wherein the multi-frequency twist-reflector is configured to selectively change the polarization for at

Abstract: A multiband antenna feed, an antenna incorporating the multiband antenna feed and a method are disclosed. An apparatus, comprises: a first port which may be configured to convey a first signal at a first frequency. A second port may configured to convey a second signal at a second frequency. The second frequency may be higher than the first frequency. A third port may be configured to convey the first signal and the second signal with a feed for a multiband antenna. The third port may have an inner waveguide and a coaxial waveguide. A first network may couple the first port with the coaxial waveguide and may be configured to propagate the first signal between the first port and the coaxial waveguide. A second network may couple the second port with the inner waveguide and may be configured to propagate the second signal between the second port and the inner waveguide.

Abstract: A folded lens antenna structure comprising: a stack comprising in order: a reflector; a dielectric gap; and a sub-reflector plate of smaller area than the reflector.

Abstract: An apparatus, for example a multi-band radio frequency antenna system, comprising: a primary reflector, for example a parabolic reflector; and a near-field feed arrangement comprising: a multi-band waveguide feed comprising a first waveguide feed for a first frequency band and a second waveguide feed for a second frequency band separate to the first frequency band, wherein the first waveguide feed and the second waveguide feed are co-axial and have, respectively, a first aperture and a second aperture; and a splashplate located within the near-field of the first waveguide feed, located within the near field of the second waveguide feed and configured as a feed for the primary reflector.

Abstract: A helical antenna comprising at least one helix which is formed by at least two radiating wires. According to the invention, at least one of said radiating wires is associated with a parasitic wire having a width which is less than or equal to the radiating wire(s), such as to broaden the bandwidth of the antenna.

Abstract: A helical antenna comprising at least one helix which is formed by at least two radiating wires. According to the invention, at least one of said radiating wires is associated with a parasitic wire having a width which is less than or equal to the radiating wire(s), such as to broaden the bandwidth of the antenna.