Abstract: The invention relates to matching asymmetrical discontinuities in transmission lines to give low reflection coefficients (less than five percent) over a wide frequency band (corresponding to at least an octave in wavelength). A group of asymmetrical discontinuities, such as impedance steps in a waveguide, are matched by considering a reference plane whose position varies with frequency at which the reflection coefficient for waves transmitted in one direction is equal to that for waves transmitted in the opposite direction. Matching elements are then provided which have a reflection coefficient at the reference plane which is equal and opposite to the reflection coefficient of the discontinuities. Matching is less difficult if the distance between the steps is less than a quarter of a guide wavelength at all frequencies in the wide band mentioned above and such an arrangement is a "reduced quarter wave transformer".

Abstract: An H-plane waveguide `T` junction is described in which matching is achieved over a full waveguide band at the waveguide which forms the stem of the `T`. Reflection from the wall facing the stem is reduced by using a probe as a monopole located about a quarter of a wavelength from the said wall. Variations with frequency in the reflection coefficient at the stem are reduced by a disc, at the foot of the probe, which acts as a radial reduced quarter wave transformer.

Abstract: The invention relates to matching asymmetrical discontinuites in transmission lines to give low reflection coefficients (less than five percent) over a wide frequency band (corresponding to at least an octave in wavelength). A group of asymmetrical discontinuites, such as impedance steps in a waveguide, are matched by considering a reference plane whose position varies with frequency at which the reflection coefficient for waves transmitted in one direction is equal to that for waves transmitted in the opposite direction. Matching elements are then provided which have a reflection coefficient at the reference plane which is equal and opposite to the reflection coefficient of the discontinuities. Matching is less difficult if the distance between the steps is less than a quarter of a guide wavelength at all frequencies in the wide band mentioned above and such an arrangement is a "reduced quarterwave transformer".

Abstract: In view of the introduction of cellular radio, there is a requirement for an antenna of simple construction which can be sold in a consumer market. While the invention meets this need it also has application to the problem of providing TM.sub.01 to TE.sub.01 made converters. The invention employs radial conductors printed on a dielectric substrate and aligned with the transverse electric field in a waveguide supporting the TM.sub.01 mode. Circumferential conductors, each coupled to one of the radial conductors, act as monopoles radiating the required field in an antenna where the radial conductors project through apertures in the waveguide. For the mode converter, both radial and circumferential conductors are inside the waveguide, with the radial conductors aligned with the transverse electric field of the TM.sub.01 mode. Arrangements for maximizing the field at the position of the radial and circumferential conductors are described as are means for preventing the propagation of unwanted modes.

Abstract: An antenna for circularly polarized high-frequency signals comprising a succession of layers. An insulating layer 10 includes openings defined by metal plated walls forming miniature horns, each having a square cross-section. A dielectric layer 19 adjacent layer 10 supports a first supply network 20 for signals whose direction of polarization is of a first type of linear polarization. An insulating layer 30 adjacent layer 19 includes openings defined by metal plated walls forming miniature waveguides each having the same square cross-section as a respective horn, at the side facing the first network 20, and having a rectangular cross-section at the other side. A dielectric layer 39 adjacent layer 30 supports a second supply network 40 for signals whose direction of polarization is perpendicular to the polarization of the signals of the first network.

Abstract: An n-port high frequency coupler for coupling opposite strip-type ports (10a, 10c) and (20a, 20c). The coupler includes transmission line stubs (10b, 10d and 20b, 20d), each having a width less than the width of the ports and being connected at one end to the corresponding port and electrically connected at the opposite end, in a central zone (40) of the coupler to the other stubs. A resonant transmission line loop is coupled to the stubs at locations which are symmetrically-disposed with respect to the central zone. The loop has a width which is substantially equal to the width of the ports and a mean length effecting establishment of a resonant frequency just below the passband of the coupler.

Abstract: A wideband power adder-divider for high-frequency circuits including a first conductive transmission line (10) for passing a high-frequency current, second and third conductive transmission lines (20) and (30) over which this high-frequency current is distributed, and a conductive wedge-shaped transition section (40) joining the first to the second and third lines. This section has two arc-shaped outer edges (41) and (42) which are tangentially connected at one end of the section to the first line and at the other end to the second and third lines. The section includes parallel slots extending transversely to the direction of propagation of the current. The parallel slots (51) to (58) have ends which are separated from the arc-shaped edges by a distance which is less than the width of the second and third transmission lines.

Abstract: An antenna element for coupling circularly-polarized radiation to a feedline. The element includes a pair of superposed planar dielectric layers. An outer surface of each layer is covered with an electrically-conductive layer forming a ground plane and having a circular opening defining respective cavities. Orthogonally-crossed dipoles are disposed between the dielectric layers and adjacent the openings for coupling radiation to the feedline through striplines also disposed between the dielectric layers.

Abstract: An arrangement for applying a DC bias current to an RF active component, such as a field effect transistor, serially-connected with an RF transmission line. The biasing current is supplied by a transmission line section connected at a junction to the transmission line. Two conductive strips, connected in parallel with the transmission line, on opposite sides of the junction, form a band-pass filter. Each of these strips is situated at a distance from the junction which is equal to approximately one-eighth of the wavelength of the signal frequency transmitted on the transmission line.

Abstract: A suspended microstrip circuit having a dielectric substrate arranged in parallel between two parallel metal planes. First and second strip conductors are provided on the substrate, the second strip conductor being in parallel with the first strip conductor and coupled thereto. A wave phenomenon can propagate through the conductor pair in an odd mode. The metal box accommodating the microwave circuit may now be much greater so that in most cases one box is sufficient. Microwave components such as Magic-T, series-T, shunt-T, circulators, filters, attenuators, can be implemented with the suspended microstrip line.

Abstract: A bandstop filter for very high frequency transmission lines having distributed constants, having several filtering elements each intended to prevent the transmission of a specific frequency band. The first filtering element is a quarter-wave filter, the second element an assembly of two transmission paths of a length such that the signals present at the outputs have opposite phases and cancel other, the third element being a quarter-wave filter, these elements being grouped such that they form an extremely compact filter which is little sensitive to proximity effects.

Abstract: A microwave device is disclosed comprising a microstrip line pattern including an open ring forming a 1/2.lambda. resonator having a narrow gap in which the electromagnetic field is closely tied to the ring.

Abstract: An energy supply arrangement for feeding microwave energy from a microwave source to the oven cavity of a microwave oven. The energy supply arrangement comprises a transmission line of the type having a conductor arranged at a small distance from a ground plane, a so-called micro-strip line. This micro-strip line is arranged within the oven cavity near the bottom wall and is, for example, in the shape of a spiral conductor disposed about a central energy feed point and dimensioned such that it radiates energy into the cavity at the same time that energy propagates along the line.