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Combining-efficiency X-band spatial power-combined array using a multilayered packaging architecture

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IEEE Trans. Microw. Theory Tech., Vol. 48, No. 10, October 2000, pp. 1769-1771.

Summary

The design of a high combining-efficiency spatial power-combined array is described in this paper. A multilayered stacked stripline architecture enables a compact stable design. An array incorporating antenna active impedance and proper amplifier matching is measured with a combining efficiency of 87%, radiating 6.8 W of an available 7.8 W into the ideal uniformly illuminated array directivity at 10.1 GHz.
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Summary

The design of a high combining-efficiency spatial power-combined array is described in this paper. A multilayered stacked stripline architecture enables a compact stable design. An array incorporating antenna active impedance and proper amplifier matching is measured with a combining efficiency of 87%, radiating 6.8 W of an available 7.8 W...

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MEMs microswitch arrays for reconfigurable distributed microwave components

Summary

A revolutionary device technology and circuit concept is introduced for a new class of reconfigurable microwave circuits and antennas. The underlying mechanism is a compact MEMs cantilever microswitch that is arrayed in two-dimensions. The switches have the ability to be individually actuated. By constructing distributed circuit components from an array, the individual addressability of the microswitch provides the means to reconfigure the circuit trace and, thus, provides the ability to either fine-tune or completely reconfigure the circuit element's behavior. Device performance can be reconfigured over a decade in bandwidth in the nominal frequency range of 1 to 100 GHz. In addition, other circuit-element attributes can be reconfigured such as instantaneous bandwidth, impedance, and polarization (for antennas). This will enable the development of next-generation communication, radar and surveillance systems with agiIity to reconfigure operation for diverse operating bands, modes, power levels, and waveforms.
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Summary

A revolutionary device technology and circuit concept is introduced for a new class of reconfigurable microwave circuits and antennas. The underlying mechanism is a compact MEMs cantilever microswitch that is arrayed in two-dimensions. The switches have the ability to be individually actuated. By constructing distributed circuit components from an array...

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An enhanced bandwidth design technique for electromagnetically coupled microstrip antennas

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IEEE Trans. Antennas Propag., Vol. 48, No. 2, February 2000, pp. 161-164.

Summary

This paper describes a method of enhancing the bandwidth of two different electromagnetically coupled microstrip antennas by utilization of a tuning stub. An approximate theory and equations are developed to demonstrate the potential bandwidth improvement and required stub impedance characteristics. A novel dual-stub design is presented that achieves better characteristics than a conventional quarter wavelength open-end stub. As examples, the bandwidth (VSWR < 2) of a conventional proximity-coupled microstrip antenna is increased from 4.8 to 8.4% and the bandwidth of a stacked aperture-coupled microstrip antenna is increased from 27.5 to 34.5% using this technique.
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Summary

This paper describes a method of enhancing the bandwidth of two different electromagnetically coupled microstrip antennas by utilization of a tuning stub. An approximate theory and equations are developed to demonstrate the potential bandwidth improvement and required stub impedance characteristics. A novel dual-stub design is presented that achieves better characteristics...

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Demonstration of a 630-GHz photomixer used as a local oscillator

Summary

We report the first successful demonstration of a photomixer local oscillator (LO) integrated with a superconducting heterodyne detector. The photomixer LO generated the difference frequency of two diode lasers by optical heterodyne conversion in low-temperature-grown GaAs. The measured receiver noise temperature, 331 K at 630 GHz, compares favorably with that achieved using a varactor-multiplier LO. We also report the design of a high-power distributed photomixer structure.
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Summary

We report the first successful demonstration of a photomixer local oscillator (LO) integrated with a superconducting heterodyne detector. The photomixer LO generated the difference frequency of two diode lasers by optical heterodyne conversion in low-temperature-grown GaAs. The measured receiver noise temperature, 331 K at 630 GHz, compares favorably with that...

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A dual-band circularly polarized aperture-coupled stacked microstrip antenna for global positioning satellite

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IEEE Trans. Antennas Propag., Vol. 45, No. 11, November 1997, pp. 1618-25.

Summary

This paper describes the design and testing of an aperture-coupled circularly polarized antenna for global positioning satellite (GPS) applications. The antenna operates at both the L1 and L2 frequencies of 1575 and 1227 MHz, which is required for differential GPS systems in order to provide maximum positioning accuracy. Electrical performance, low-profile, and cost were equally important requirements for this antenna. The design procedure is discussed, and measured results are presented. Results from a manufacturing sensitivity analysis are also included.
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Summary

This paper describes the design and testing of an aperture-coupled circularly polarized antenna for global positioning satellite (GPS) applications. The antenna operates at both the L1 and L2 frequencies of 1575 and 1227 MHz, which is required for differential GPS systems in order to provide maximum positioning accuracy. Electrical performance...

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A multilayered packaging architecture for spatial power combined arrays

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Published in:
IEEE Antennas and Propagation Society Int. Symp. 1998 Digest, Vol. 1, 21-26 June 1998, pp. 494-7.

Summary

The explosion of interest in high data rate communications places great demands on current antenna designs. Antennas used for transmitting signals can require high gain with high radiated power. An efficient means to accomplish these goals is the free space combining of many amplifiers via elements in an antenna array. Combining the output power of the MMIC amplifiers in space obviates the circuit losses associated with connecting many amplifiers in parallel and results in potentially more efficient transmitting antennas. However, the implementation of arrays with many MMIC amplifiers and antenna elements requires a compact, multilayered packaging architecture to achieve the density of circuits with desired performance.
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Summary

The explosion of interest in high data rate communications places great demands on current antenna designs. Antennas used for transmitting signals can require high gain with high radiated power. An efficient means to accomplish these goals is the free space combining of many amplifiers via elements in an antenna array...

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A modified transmission line model for cavity backed microstrip antennas

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IEEE Antennas and Propagation Society Int. Symp. 1997 Digest, Vol. 4, 13-18 July 1997, pp. 2139-42.

Summary

Spatial power combining of many MMIC amplifiers at millimeter wave frequencies using a fixed array of microstrip antenna elements places unique demands on dielectric media. The substrate must be relatively thick to allow space for MMIC placement, must provide rather high thermal conductivity to disipate MMIC heat, and be of high dielectric constant to shrink circuit element dimensions. Presently, microstrip antenna models require a low dielectric constant substrate to be valid. This paper presents a modified transmission line model on the model of Pues and Van de Capelle which addresses the problems of thick, high microstrip antenna elements. The goal of the model was to guide design of a microstrip array antenna suitable for a spatial power combined module.
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Summary

Spatial power combining of many MMIC amplifiers at millimeter wave frequencies using a fixed array of microstrip antenna elements places unique demands on dielectric media. The substrate must be relatively thick to allow space for MMIC placement, must provide rather high thermal conductivity to disipate MMIC heat, and be of...

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45-GHz MMIC power combining using a circuit-fed, spatially combined array

Published in:
IEEE Microw. Guid. Wave Lett., Vol. 7, No. 1, January 1997, pp. 15-17.

Summary

We describe the design and measurement of a hybrid-circuit, tile-approach subarray for use in spatial power-combined transmitters. The subarray consists of 16 monolithic millimeter-wave integrated circuit (MMIC) amplifiers, each feeding a circularly polarized cavity-backed microstrip antenna. The average performance across the 43.5-45.5 GHz band is as follows: EIRP 18.3 dBW, dc-RF efficiency 10.3%, effective transmitter power 530 mW, system gain 13.2 dB, and combining efficiency of 46.2%. The minimum axial ratio is 1.2 dB at 43.9 GHz, and the array has a 3% 3-dB axial ratio bandwidth.
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Summary

We describe the design and measurement of a hybrid-circuit, tile-approach subarray for use in spatial power-combined transmitters. The subarray consists of 16 monolithic millimeter-wave integrated circuit (MMIC) amplifiers, each feeding a circularly polarized cavity-backed microstrip antenna. The average performance across the 43.5-45.5 GHz band is as follows: EIRP 18.3 dBW...

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A 16-element subarray for hybrid-circuit tile-approach spatial power combining

Published in:
IEEE Trans. Microw. Theory Tech., Vol. 44, No. 11, November 1996, pp. 2093-8.

Summary

Three designs for a 4-by-4 are described for use in a spatial power-combined transmitter. The subarrays are constructed using a hybrid-circuit, tile-approach architecture and are composed of 16 cavity-backed, proximity-coupled microstrip antennas, each fed by a 0.5 watt amplifier. Both linearly and circularly polarized subarrays have been constructed for operation over a 10% band centered at 10 GHz. The linearly polarized subarray showed the following peak performance: EIRP greater than 27 dBW, effective transmitter power greater than 5 watts, dc-RF efficiency greater than 20%, and excellent graceful degradation performance.
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Summary

Three designs for a 4-by-4 are described for use in a spatial power-combined transmitter. The subarrays are constructed using a hybrid-circuit, tile-approach architecture and are composed of 16 cavity-backed, proximity-coupled microstrip antennas, each fed by a 0.5 watt amplifier. Both linearly and circularly polarized subarrays have been constructed for operation...

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Experimental comparison of the radiation efficiency for conventional and cavity backed microstrip antennas

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Published in:
IEEE Antennas and Propagation Society Intl Symp., 21-26 July 1996.

Summary

The radiation efficiency of conventional microstrip antennas generally decreases when the substrate thickness or permittivity is increased because of loss to surface waves. However, constructing a metal cavity around the microstrip antenna prevents the surface wave propagation. Thus, the cavity backed microstrip antenna has been predicted to have increased radiation efficiency. In this paper, we compare conventional and cavity backed microstrip patch antennas on substrates with an electrical thickness of 0.067 ho and dielectric constants of ~r=2.94, 6.15, and 10.2. As one would expect, the radiation efficiency of the conventional patch decreases with increasing dielectric constant, but the efficiency remains relatively constant for the cavity backed patch. In this work, three different methods are used to measure the radiation efficiencies: a far field gain comparison, a Wheeler cap method and an input admittance method.
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Summary

The radiation efficiency of conventional microstrip antennas generally decreases when the substrate thickness or permittivity is increased because of loss to surface waves. However, constructing a metal cavity around the microstrip antenna prevents the surface wave propagation. Thus, the cavity backed microstrip antenna has been predicted to have increased radiation...

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