Comsat Corporation

Communications Satellite Corporation

Other

Bernard D Geller

Robert M Sorbello

Amir Ibrahim Zaghloul

Krishna P Pande

Amin Ezzeddine

Gamal M Hegazi

Francois T Assal

Ramesh K Gupta

Louis B Holdeman

John I Upshur

Fred R Phelleps

Eric Christopher Kohls

Johann U Tyler

George F Laird, Iii

Richard C Mott

In a flat plate antenna, insertion loss is reduced significantly by providing an extensive waveguide structure at the back of the ground plane of the antenna. Depending on antenna size, the waveguide may feed the antenna at one or a plurality of points. According to a preferred embodiment, the transition from waveguide to stripline is made via a coaxial connection, with a quarter-wave transformation, including mode suppression walls to direct the energy more efficiently. Alternatively, a direct waveguide to stripline transition may be provided. The technique has wide applicability to a number of antenna designs, including single- and dual-polarization structures, and linear and circular polarization operation.

Waveguide transition for flat plate antenna

Contactless coupling of a low-noise block down-converter (LNB) imbedded within a flat antenna is achieved by mounting the LNB on a power summing/combining network layer of the antenna, and coupling the transition capacitively to the power summing/combining network in a stripline-to-stripline transition. The contactless coupling facilitates antenna manufacture by allowing the rapid testing of the LNB and its final assembly into the antenna.

Flat antenna low-noise block down converter capacitively coupled to feed

A monolithic gallium arsenide (GaAs) phased array using integrated gold (Au) posts for interconnecting multiple substrate layers. The phased array includes a GaAs substrate having transmit/receive modules fabricated on one side and radiating elements etched on the backside of the same substrate. The conductive gold posts are integrated on the same side with the transmit/receive modules and interconnect the transmit/receive modules with a distribution network which is printed on a second substrate. Gold posts are also used to interconnect DC bias and control lines of the two substrates.

Method of assembling a monolithic gallium arsenide phased array using

Monolithic gallium arsenide phased array using integrated gold post

A compact multi-layer flat antenna structure incorporating a low noise block down-converter on the power divider network layer of the antenna. RF circuit losses are reduced, and the antenna/receiver combination is made more compact, for flush mounting. The antenna/receiver combination finds particular utility in direct broadcast satellite (DBS) applications for single or dual orthogonal polarizations. The connection between the antenna and receiver may be implemented in stripline/coplanar waveguide, or other known technologies such as microstrip, slotline, and finline.

Low noise block down-converter for direct broadcast satellite receiver

A low loss reflection-type analog phase shifter circuit producing a large range (nearly 360.degree.) of phase shift at X-band while achieving low attenuation (insertion loss) and little amplitude variation over all phase states. The results are achieved, in part, by using a terminating impedance which includes parallel-connected hyperabrupt varactor diodes. The circuit is implemented readily in a monolithic microwave integrated circuit using GaAs.

Low loss 360 degree X-band analog phase shifter

Integration and packaging of monolithic microwave integrated circuits (MMIC) components is facilitated by using a motherboard comprising high resistivity silicon, which having a thermal conductivity three times that of gallium arsenide. Ultra high purity, uncompensated silicon preferably is used. Anisotropic etching of recesses in the motherboard facilitates precise placement of the MMICs in the recesses, enabling use of automated die and wire bonding techniques to reduce required assembly time substantially. Using a silicon motherboard also ultimately enables incorporation of required control circuitry. The silicon motherboard also transmits RF energy well, a useful characteristic particularly in C-band and X-band applications in which microstrip is used, though other transmission media function well at even higher frequencies.

Method of packaging microwave semiconductor components and integrated

An RF power combiner combines the power of several microwave high power FET amplifiers. A plurality of baluns which convert a balanced transmission line to an unbalanced transmission line and have outputs which are 180.degree. out of phase from each other may be connected at the inputs and the outputs of the FETs. This connection allows for very high output power while matching impedances of the input and the output of the power combiner. Additionally, loss in the output circuit can be minimized by connecting equi-phase outputs of the FETs in a parallel/push-pull manner.

RF power combiner using baluns

An attenuator element has a reference path and a relative attenuation path. The reference path is formed by a T-network of two FETs operated in the passive mode and a shunt path and the attenuation path is formed with a similar structure, with the FETs in the shunt path having a different channel width. Instead of a T-network, a Pi-network of transistors can be used. The respective gates of the FETs along the reference path are connected to a first control input corresponding to either zero volts or the pinch-off voltage and the respective gates of the transistors on the attenuation path are connected to a complementary control input having a voltage corresponding to the other of zero volts and the pinch-off voltage. Another type of attenuator element is formed with a reference path having a transmission line and an attenuation path formed by a resistive T-network, with the attenuation and reference paths being alternately selectable by two single pole, double throw switches. The switches can also be formed by FETs operated in the passive mode, and be controlled by a control signals corresponding to either zero volts or the pinch-off voltage. Using one type or mixing both types of attenuator elements, an attenuator device is formed. The attenuator may be used in any attenuator application, and is especially applicable to on-board transponder applications in a communications satellite, and phased array antenna and radar applications.

Microwave digitally controlled solid-state attenuator having parallel

A technique for packaging and integrating of a microwave integrated circuit (MIC) or monolithic microwave integrated circuit (MMIC) with a waveguide uses a printed conductive circuit pattern on a dielectric substrate to transform impedance and mode of propagation between the MIC/MMIC and the waveguide. The virtually coplanar circuit pattern lies on an equipotential surface within the waveguide and therefore makes possible single or dual polarized mode structures.

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Rockville, MD, United States of America

Bernard D Geller