Abstract: A polarizing screen for altering a polarization state of a radio frequency waveform radiated from a parallel plate waveguide (PPW) wherein the waveform has a centre frequency and a bandwidth, the polarizing screen comprising a plurality of developable sheets arranged stacked in parallel to each other in direction of a local normal vector of a first sheet at respective inter-sheet spacings, each sheet comprising an electrically conductive pattern forming a one-dimensional periodic structure of unit-cells in an extension direction, wherein the periodic structure is associated with a height measured orthogonally to the extension direction and orthogonally to the local normal vector of the shat, where each cell comprises an aperture configured to transmit the radio frequency waveform at a predetermined polarization state, wherein the height is determined in dependence of the centre frequency and/or the bandwidth of the radio frequency waveform such that the pre-determined polarization state is provided as well as

Abstract: A waveguide power divider device comprises four two-port orthomode junctions arranged with their common waveguides extending in parallel, wherein the two ports of each orthomode junction extend in orthogonal directions, four E-plane T-junctions, each T-junction coupling two of the four orthomode junctions to each other via respective ones of their ports, a four-port turnstile junction, wherein waveguides of the four ports are bent to extend in parallel to an extension direction of a common waveguide of the turnstile junction, and four waveguide twists, each waveguide twist coupling a common waveguide of a respective one of the T-junctions to the waveguide of a respective one of the ports of the turnstile junction, with broad walls of the common waveguide of the T-junction and of the waveguide of the port of the turnstile junction being orthogonal to each other. An array antenna may include one or more such waveguide power divider devices.

Abstract: A waveguide component for an orthomode junction or an orthomode transducer includes a common waveguide with a longitudinal direction, the common waveguide includes at least a first portion and a second portion with different cross-sections, and two coupling probes, each arranged orthogonally to the longitudinal direction. The coupling probes are further arranged to couple to different polarization components of an electromagnetic field present in the common waveguide. The second portion of the common waveguide has a cross-section with at most two-fold rotational symmetry.

Abstract: A filter for filtering an electromagnetic wave and a filter design method are provided. The filter comprises a cavity with a first plate and a second plate, the first and second plates are opposite to each other. The first plate comprises a number of elements distributed on the side of the first plate facing the cavity, wherein a location of each element on the first plate is defined in a coordinate system. The second plate comprises a number of elements distributed on the side of the second plate facing the cavity according to the locations of the elements on the first plate, wherein each element is distributed on the second plate with an offset with respect to a corresponding element on the first plate.

Abstract: A waveguide power divider device comprises four two-port orthomode junctions arranged with their common waveguides extending in parallel, wherein the two ports of each orthomode junction extend in orthogonal directions, four E-plane T-junctions, each T-junction coupling two of the four orthomode junctions to each other via respective ones of their ports, a four-port turnstile junction, wherein waveguides of the four ports are bent to extend in parallel to an extension direction of a common waveguide of the turnstile junction, and four waveguide twists, each waveguide twist coupling a common waveguide of a respective one of the T-junctions to the waveguide of a respective one of the ports of the turnstile junction, with broad walls of the common waveguide of the T-junction and of the waveguide of the port of the turnstile junction being orthogonal to each other. An array antenna may include one or more such waveguide power divider devices.

Abstract: A directional coupler (100) comprises two hollow bodies (200, 201) forming two waveguide portions. Each hollow body has an open end arranged at a first side (10) of the hollow body and another open end arranged at a second side (20) of the hollow body opposite to the first side in a longitudinal direction (30) of the hollow body. The hollow body has a first cross section perpendicular to the longitudinal direction. A second cross section along the longitudinal direction defines a first plane of propagation of the electric field. The two waveguide portions have a common wall along the longitudinal direction (30) forming a septum (400) between the two waveguide portions on a second plane orthogonal to the first plane. The septum has an aperture (410) for coupling the two waveguide portions. The aperture has a shape comprising a part (420) slanted with respect to the longitudinal direction.

Abstract: This specification describes a process and apparatus for treating water comprising selenium. A process is described having the steps of treating the wastewater influent using a biological reduction process to produce an intermediary stream and reducing the concentration of unconsumed constituents in the intermediary stream by means of filtration optionally with upstream coagulation or flocculation. When compared to the wastewater influent, the intermediary stream preferably has reduced concentration of the selenium species when compared to the wastewater influent. When compared to the intermediary stream, the effluent preferably has reduced concentration of one or more of the inorganic non-metallic constituents (such as nitrogen, phosphorous and sulphur), metallic constituents or organic constituents. An apparatus is described herein having a fixed film reactor configured to receive a wastewater influent, and a membrane filter configured to receive effluent from the fixed film reactor.

Abstract: A polarizing reflector for broadband antennas includes a flat dielectric substrate, a patch array layer formed by a bi-dimensionally periodic lattice of thin metallic patches along first and second perpendicular directions x, y, and a ground layer. All the patches have a same shape elongated along the second direction y and form electric dipoles when electrically excited along the second direction y. For each row the patches of the said row are interconnected by an elongated metallic strip oriented along the first direction x and having a width c.

Abstract: A directional coupler (100) comprises two hollow bodies (200, 201) forming two waveguide portions. Each hollow body has an open end arranged at a first side (10) of the hollow body and another open end arranged at a second side (20) of the hollow body in opposite to the first side in a longitudinal direction (30) of the hollow body. The hollow body has a first cross section perpendicular to the longitudinal direction. A second cross section along the longitudinal direction defines a first plane of propagation of the electric field. The two waveguide portions have a common wall along the longitudinal direction (30) forming a septum (400) between the two waveguide portions on a second plane orthogonal to the first plane. The septum has an aperture (410) for coupling the two waveguide portions. The aperture has a shape comprising a part (420) slanted with respect to the longitudinal direction.

Abstract: A polarizing reflector for broadband antennas includes a flat dielectric substrate, a patch array layer formed by a bi-dimensionally periodic lattice of thin metallic patches along first and second perpendicular directions x, y, and a ground layer. All the patches have a same shape elongated along the second direction y and form electric dipoles when electrically excited along the second direction y. For each row the patches of the said row are interconnected by an elongated metallic strip oriented along the first direction x and having a width c.

Abstract: A media bed in a biological reactor is backwashed in a plurality of short pulses. An outlet of the reactor is preferably located above, but close to, the top of the bed. During a pulse, the outlet is closed and the bed may be fluidized or otherwise expanded to above the level of the outlet. Between pulses, the bed settles to below the level of the outlet.

Abstract: A system for treating wastewater containing selenium has a sequencing batch reactor upstream of a fixed film reactor. The sequencing batch reactor may be operated under anoxic conditions while influent is mixed with residual sludge. The SBR reduces total nitrogen, suspended solids, or both. Selenium is removed in the fixed film reactor by biological reduction to elemental selenium.

Abstract: A media bed reactor may be used to remove selenium from water. An exemplary reactor has a fluid injection system with one or more outlets located within the media bed. The fluid injection system may be connected to a source of gas, liquid or both. In a selenium treatment process, a denitrification zone forms above a selenium-reducing zone in the media bed. Operation of the reactor includes a step of flowing a fluid upwards through only an upper part of the bed. This upper part of the bed preferably contains at least most of the denitrification zone.

Abstract: A bioreactor has a biofilm supporting bed with at least two types of media. An upper media is relatively porous, preferably porous enough to admit particles of a lower media. In use, wastewater flows downwards through the bed. Soluble nitrogen is reduced in the upper media and converted into nitrogen gas. Nitrogen gas bubbles rise through the upper media and escape from the bed. Selenium is reduced in the lower media and converted into elemental selenium. The elemental selenium is released periodically by backwashing the bed, which may cause fluidization or other expansion of the lower media into the upper media.

Abstract: A beamformer comprises a transmission line fed by at least one input feed source, the transmission line comprising two stacked metal plates extending, along two directions, longitudinal X and transverse Y. The transmission line further comprises at least one protuberance extending in the directions X, Y, and in a direction Z orthogonal to the plane XY, the protuberance comprising a metal insert extending in the directions X and Y and extending height-wise in the direction Z, the insert comprising a base fastened to one of the two metal plates and a free end and having a contour of variable length between the two lateral edges of the transmission line. In the protuberance, the transmission line is adjoining the insert and forms, in the direction Z, a circumvolution around the insert.

Abstract: A mode extractor for extracting TM01 mode from an electromagnetic signal, including a first and second turnstile junction, each of the turnstile junctions having first port, four second ports of rectangular waveguide which are mutually orthogonal and orthogonal to first port and matching section provided at least partially in center region of respective turnstile junction, center region being located at intersection of first port and four second ports wherein first and second turnstile junction are arranged so that longitudinal axes of their first ports are aligned with each other and their first ports are facing in opposite directions, each of the second ports of first turnstile junction is electromagnetically coupled to corresponding one of second ports of second turnstile junction, and a coaxial coupling device is inserted into matching section of first turnstile junction so that a portion of coaxial coupling device extends into first port of first turnstile junction.

Abstract: A beamformer comprises a transmission line fed by at least one input feed source, the transmission line comprising two stacked metal plates extending, along two directions, longitudinal X and transverse Y. The transmission line further comprises at least one protuberance extending in the directions X, Y, and in a direction Z orthogonal to the plane XY, the protuberance comprising a metal insert extending in the directions X and Y and extending height-wise in the direction Z, the insert comprising a base fastened to one of the two metal plates and a free end and having a contour of variable length between the two lateral edges of the transmission line. In the protuberance, the transmission line is adjoining the insert and forms, in the direction Z, a circumvolution around the insert.

Abstract: A media bed reactor may be used to remove selenium from water. An exemplary reactor has a fluid injection system with one or more outlets located within the media bed. The fluid injection system may be connected to a source of gas, liquid or both. In a selenium treatment process, a denitrification zone forms above a selenium-reducing zone in the media bed. Operation of the reactor includes a step of flowing a fluid upwards through only an upper part of the bed. This upper part of the bed preferably contains at least most of the denitrification zone.

Abstract: A media bed in a biological reactor is backwashed in a plurality of short pulses. An outlet of the reactor is preferably located above, but close to, the top of the bed. During a pulse, the outlet is closed and the bed may be fluidized or otherwise expanded to above the level of the outlet. Between pulses, the bed settles to below the level of the outlet.

Abstract: A bioreactor has a biofilm supporting bed with at least two types of media. An upper media is relatively porous, preferably porous enough to admit particles of a lower media. In use, wastewater flows downwards through the bed. Soluble nitrogen is reduced in the upper media and converted into nitrogen gas. Nitrogen gas bubbles rise through the upper media and escape from the bed. Selenium is reduced in the lower media and converted into elemental selenium. The elemental selenium is released periodically by backwashing the bed, which may cause fluidization or other expansion of the lower media into the upper media.