It is no longer necessary to use extrapolated microwave dielectric values when designing millimeter-wave components and systems. Very recently, highly accurate millimeter-wave (5- to 1/2-mm) data on complex dielectric permittivity and loss tangent have become available to engineers for a variety of materials such as common ceramics, semiconductors, crystalline, and glass materials. One quasi-optical measurement method has proved to be most accurate and reproducible, namely, dispersive Fourier transform spectroscopy (DFTS) applied to a polarizing interferometer. The openresonator method and the Mach-Zehnder-IMPATT spectrometer will also be described and compared. The fact that the dielectric loss increases with frequency in the millimeter, unlike the microwave, is an important feature of these data. Reliable measurements also reveal that the methods of preparation of nominally identical specimens can change the dielectric losses by a factor of three.

Millimeter-wave dielectric measurement of materials

Improved heat dissipation in InP Gunn devices resulted in RF power levels exceeding 200, 130, 80, and 25 mW at oscillation frequencies of around 103, 132, 152, and 162 GHz, respectively. Corresponding dc-to-RF conversion efficiencies exceeded 2.3% from 102 to 132 GHz. Power combining increased the available RF power levels to over 300 mW at 106 GHz, around 130 mW at 136 GHz, and more than 125 mW at 152 GHz with corresponding combining efficiencies from 80% to over 100%. Operation in a second harmonic mode yielded RF power levels of more than 3.5 mW at 214 GHz, over 2 mW around 220 GHz as well as over 1 mW around 280, 300, and 315 GHz. RF power levels exceeding 10 mW at 202 GHz, 9 mW around 210 GHz, and 4 mW around 235 GHz were obtained from GaAs TUNNETT diodes in a second harmonic mode as well. Corresponding dc-to-RF conversion efficiencies were around 1% at 202 and 210 GHz.

Recent advances in the performance of InP Gunn devices and GaAs TUNNETT diodes for the 100-300-GHz frequency range and above

The design, experimental evaluation and performance of a Traveling-Wave Uni-Traveling Carrier photodiode for Terahertz generation are described and its advantages in terms of frequency response are demonstrated. The device delivered 148 microW at 457 GHz, 24 microW at 914 GHz when integrated with resonant antennas and 105 microW at 255 GHz, 30 microW at 408 GHz, 16 microW at 510 GHz and 10 microW at 612 GHz. Record levels of Terahertz figure of merit (PTHz/Popt2 in W(-1)) were achieved ranging from 1 W(-1) at 110 GHz to 0.0024 W(-1) at 914 GHz.

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Traveling-wave Uni-Traveling Carrier Photodiodes for continuous wave THz generation

Recent progress in magnetically confined plasma research has brought the goal of controlled thermonuclear fusion within reach. Simultaneously, the increased size, temperature, and density of these devices has resulted in rapid changes in diagnostic techniques. In this article, recent developments in instrumentation are reviewed together with trends for the future. The topics discussed include far‐infrared laser interferometry and polarimetry, ruby laser television Thomson scattering, excimer and Nd‐glass laser scattering, ion temperature determination via large‐α scattering with FIR and CO2 lasers, collective scattering, Schottky diode mixer technology, synchrotron radiation diagnostics and imaging, ion beam probes, x‐ray diagnostics and imaging, neutron diagnostics, resonance fluorescence scattering, ultraviolet diagnostics, and internal magnetic field measurement.

Instrumentation for magnetically confined fusion plasma diagnostics

This paper gives an overview of measurement techniques used in the THz region of the electromagnetic spectrum, from about 100 GHz to several THz Currently available components necessary for THz metrology, such as sources, detectors and passives, are briefly described A discussion of power measurements, vector network analysis and antenna measurements as well as the limitations of these measurements at THz frequencies is given The paper concludes with a summary of available components and instrumentation for THz metrology at the time of writing

THz Metrology and Instrumentation

Submillimetre-wave silicon single-drift-region IMPATT diodes with a p+?p?n+ structure have been fabricated by ion implantation. C.W. output powers of 7.5 mW at 285 GHz and 78 mW at 185 GHz were obtained. The maximum c.w. oscillation frequency observed was 394 GHz.

C.W. oscillation with p+-p-n+ silicon IMPATT diodes in 200 GHz and 300 GHz bands

400 and 300 GHz c.w. oscillation characteristics for liquid-nitrogcn-cooled silicon IMPATT diodes are described. Output powers of 2.2 and 4.5 mW have been obtained at 412 and 295 GHz, respectively, and a highest oscillation frequency of 430 GHz observed.

Liquid-nitrogen-cooled submillimetre-wave silicon IMPATT diodes

80 GHz band silicon d.d.r. Impatt diodes with diamond heatsinks were fabricated. An output power of 1014 mW at 77.70 GHz was obtained by liquid-nitrogen-cooled operation, which gives the highest pf2 product, and 726 mW at 73.35 GHz by room temperature operation. Small-signal diode impedance was calculated considering operating temperature.

M. Ino

Papers

C.W. oscillation with p+-p-n+ silicon IMPATT diodes in 200 GHz and 300 GHz bands

Liquid-nitrogen-cooled submillimetre-wave silicon IMPATT diodes

80 GHz silicon diamond-heatsink Impatt diodes