Communications Satellite Corporation

International Telecommunications Satellite Organization (intelsat)

Ronald E Stegens

Gary G Hawisher

A coplanar waveguide quadrature hybrid is herein disclosed which produces even E-field symmetry about the center line of transmission during both even-and odd-mode excitation. In a first embodiment of the present invention, a first coupling element of a generally elongated shape is bifurcated and is interconnected at its ends to form a first rectangular coupling element. A second rectangular coupling element is disposed within the first rectangular coupling element. In a second embodiment of the present invention, one of the short sides of a first rectangular coupling element is broken and is cross-coupled to a third rectangular coupling element similar to the second rectangular coupling element, the third rectangular coupling element being disposed within a fourth rectangular coupling element similar to the first coupling element. The fourth rectangular coupling element is then directly connected to the second rectangular element to form a composite coupling element. During odd-mode excitation, the resulting CPW structures do not create an E-field between the ground planes and thus eliminate the spurious 'slot-line' mode of operation of prior art CPW devices.

Coplanar waveguide quadrature hybrid having symmetrical coupling

A push-pull microwave amplifier in which an input signal is split into two ransmission paths in a manner which simulates the behavior of a center-tapped transformer over a broad frequency range. The input signal is first divided into two identical paths and then passed down first and second transmission line segments in the two paths bi-directionally. One of the transmission line segments is terminated in an open circuit and the other in a short circuit so that the reflected signals have the opposite polarities. By making the transmission line segments of equal length, the opposite polarity signals emerge from the transmission line segments at the same time. The signals are then amplified and then passed again bi-directionally along third and fourth transmission line segments terminated in short and open circuits so as to re-convert the signals to the same polarity. The signals are then summed to produce the composite amplified output signal.

Push-pull microwave amplifier

A versatile test structure for coplanar waveguide (CPW) microwave integrated circuits is provided with a support structure or carrier which accommodates any length of CPW circuit. The carrier is provided with a shock mounting means for a CPW substrate which protects the substrate against physical damage, as well as damage caused by widely varying thermal coefficients of expansion. The carrier is provided at each end thereof with a sliding connector to inject or remove microwave energy from the CPW substrate via a coaxial connector. The sliding connector and the carrier together comprise a mounting structure for the substrate which may be further provided with a sliding energy sampler or a right-angle CPW transition which may be used to sample energy levels within the substrate, or test individual portions of a CPW circuit.

Coplanar waveguide mounting structure and test fixture for microwave

A non-magnetized ferrite material is provided as the propagating medium for a microwave transmission line such as a microstrip or stripline transmission line. The transmission system is adapted to provide a 'high pass' filter characteristic by selecting the saturation magnetization of the ferrite as a function of the desired cut-off frequency such that frequencies below the cut-off are absorbed by the ferrite material thereby producing a low reflection coefficient, while frequencies above the cut-off are transmitted with very little attenuation. One of the conductors of the transmission system can further have microwave circuit elements located thereon which provide a second 'filter' characteristic, such as a reactive filter or a tunnel diode. The filter characteristics produced by the ferrite material and the circuit elements combine to produce a desired system filter characteristic.

Ferrite substrate microwave filter

The Frequency response of a Microstrip Interdigital Filter (MIDF) is improved by providing a specially dimensioned top cover separated from the MIDF ground plane along one or both of its edges by a dielectric layer comprised of thin dielectric sheets. While the upper frequency skirt is mainly determined by the MIDF itself, the bandwidth may be reduced and the slope of the lower frequency skirt may be enhanced by providing the cover in accordance with the invention. The thickness of the dielectric layer can be chosen to further improve the slope of the low frequency skirt by effectively moving the filter zero closer to the desired low frequency cut-off of the filter. The particular choice of the dielectric thickness will not substantially affect the filter bandwidth.

Quasi-elliptic function microstrip interdigital filter

A method of fabrication and apparatus are disclosed for realizing a high-frequency non-transverse electromagnetic (non-TEM) mode interdigital band-pass filter. The filter has interdigital microstrip resonators R.sub.i separated a constant distance H from a ground plane by a propagation medium. The method of fabrication allows the W.sub.i /H.sub.i and S.sub.i,i+1 /H.sub.i dimensions of the filter to be obtained. The method starts by determining the self and mutual admittance values Y.sub.i,i and Y.sub.i,i+1, respectively, of each resonator R.sub.i. An estimate for W.sub.i /H.sub.i for each resonator can be made, if desired, using a single microstrip approach. The W.sub.i /H.sub.i estimates are used to obtain the S.sub.i,i+1 /H.sub.i value for each adjacent pair of resonators R.sub.i,R.sub.i+1. The S.sub.i,i+1 /H.sub.i values are used to obtain the values for Y.sub.f and/or Y.sub.fe for each resonator R.sub.i. The values for Y.sub.f and/or Y.sub.fe are used to calculate the value for Y.sub.pp for each resonator R.sub.i. Each Y.sub.pp value is used to obtain a value for W.sub.i /H.sub.i. The method of fabrication is convergent and can be iterated to obtain convergent values for S.sub.i,i+1 /H.sub.i and W.sub.i /H.sub.i so that a filter can be produced having the desired electrical passband response.

Growing community of inventors

Brookeville, MD, United States of America

Ronald E Stegens