Abstract: An antenna module, in particular for a base station of a cellular mobile radio network, comprising a group of radiating elements capable of receiving and/or transmitting electromagnetic waves having at least two different, preferably linear orthogonal, polarizations, said antenna module further comprising at least one passive decoupling element. Said decoupling element extends with its longest dimension in a direction which is substantially perpendicular to a direction of propagation of said electromagnetic waves and/or substantially parallel to a ground plane and thus improves a degree of decoupling between said polarizations.

Abstract: A waveguide directional filter for combining multiple high power UHF television broadcasting transmitters on to a common antenna. The directional filter arrangement includes an input waveguide, an output waveguide and an interconnected cascade assembly of two or more cavity resonators. The input and output waveguides are each aperture-coupled to an end cavity resonator of the cascade assembly. The edges of each aperture incorporate inwardly extending curved protrusions of a characteristic shape. Alternatively or additionally, at least one pair of non-adjacent cavity resonators are coupled by at least one additional coupling element incorporating an external transmission line.

Abstract: A waveguide directional filter for combining multiple high power UHF television broadcasting transmitters on to a common antenna. The directional filter arrangement includes an input waveguide, an output waveguide and an interconnected cascade assembly of two or more cavity resonators. The input and output waveguides are each aperture-coupled to an end cavity resonator of the cascade assembly. The edges of each aperture incorporate inwardly extending curved protrusions of a characteristic shape. Alternatively or additionally, at least one pair of non-adjacent cavity resonators are coupled by at least one additional coupling element incorporating an external transmission line.

Abstract: An antenna module, in particular for a base station of a cellular mobile radio network, comprising a group of radiating elements capable of receiving and/or transmitting electromagnetic waves having at least two different, preferably linear orthogonal, polarizations, said antenna module further comprising at least one passive decoupling element. Said decoupling element extends with its longest dimension in a direction which is substantially perpendicular to a direction of propagation of said electromagnetic waves and/or substantially parallel to a ground plane and thus improves a degree of decoupling between said polarizations.

Abstract: A waveguide directional filter for combining multiple high power UHF television broadcasting transmitters on to a common antenna. The directional filter arrangement includes an input waveguide, an output waveguide and an interconnected cascade assembly of two or more cavity resonators. The input and output waveguides are each aperture-coupled to an end cavity resonator of the cascade assembly. The edges of each aperture incorporate inwardly extending curved protrusions of a characteristic shape. Alternatively or additionally, at least one pair of non-adjacent cavity resonators are coupled by at least one additional coupling element incorporating an external transmission line.

Abstract: A phase shifter element for selectively varying the phase of signals of desired frequencies or frequency range passing through an adjacent transmission line associated with, for example, an antenna array to electrically down-tilt the array's electromagnetic wave pattern. The phase shifter element comprises a planar dielectric member having at least three discrete coplanar interactive segments extending from an edge thereof and arranged to movably overlap the adjacent transmission line to vary its dielectric constant. Optimum dimensions of each interactive segments and optimum widths of gaps defined by opposite edges of adjacent segments being determined by a computer optimisation program, such that the phase shifter element achieves a wide operating frequency and minimum aggregate reflection.

Abstract: A waveguide directional filter for combining multiple high power UHF television broadcasting transmitters on to a common antenna. The directional filter arrangement includes an input waveguide, an output waveguide and an interconnected cascade assembly of two or more cavity resonators. The input and output waveguides are each aperture-coupled to an end cavity resonator of the cascade assembly. The edges of each aperture incorporate inwardly extending curved protrusions of a characteristic shape. Alternatively or additionally, at least one pair of non-adjacent cavity resonators are coupled by at least one additional coupling element incorporating an external transmission line.

Abstract: A waveguide directional filter is described for combining multiple high power UHF television broadcasting transmitters on to a common antenna. The filter arrangement comprises an input waveguide (1) and an output waveguide (2). The waveguides are rectangular having broad walls (3) joined by narrow walls (4) whose width/height ratio is approximately 4:1. The two waveguides are connected by at least one direct-coupled cavity resonator (5). Coupling between the cavity and each waveguide is obtained by a respective characteristic aperture (7, 7a) in the form of a rectangle whose four sides have inwardly extending hemicycle sectors (8, 9, 10 and 11).

Abstract: A phase shifter element for selectively varying the phase of signals of desired frequencies or frequency range passing through an adjacent transmission line associated with, for example, an antenna array to electrically down-tilt the array's electromagnetic wave pattern. The phase shifter element comprises a planar dielectric member having at least three discrete co-planar interactive segments extending from an edge thereof and arranged to movably overlap the adjacent transmission line to vary its dielectric constant. Optimum dimensions of each interactive segment and optimum widths of gaps defined by opposite edges of adjacent segments being determined by a computer optimisation program, such that the phase shifter element achieves a wide operating frequency and minimum aggregate reflection.

Abstract: A dual band combiner for combining two frequency bands having a 2:1 relationship, e.g. 900 MHz and 1800 MHz. The combiner comprises an upper frequency bandpass filter section and an upper frequency bandstop filter. The bandpass filter section comprises two open-end resonators whose lengths are 1/2 wavelength of the upper frequency band, and the bandstop filter comprises three open-end resonators whose lengths are 1/4 wavelength of the upper frequency band. Because of the 2:1 frequency relationship pronounced selectivity-enhancing transmission zeros are produced at the lower frequency band, thereby providing a combiner that has high isolation between ports while maintaining low insertion loss.

Abstract: The antenna element comprises a printed circuit board (1) on one side of which is a conductive ground plane (2); and on the other side of which are two symmetrical conductive feed tracks (3,4) which excite orthogonal slot apertures (12,13, 22, 23) etched in the ground plane. Radiation from the slots induces orthogonal currents into a radiating patch (14, 18) supported in a spaced relationship with the slots. Two signals can be radiated from the patch simultaneously with 90.degree. separation in polarization. The slots radiate to the rear as well as to the front. A symmetrical conductive cavity (17, 25) enclosing the slots contains rear radiation.