Circular groove shaped resonator for millimeter waves

In millimeter wave lengths region semiconductor generators, amplifiers, mixers and other solid state UHF devices find a wide application. In our work, we suggested to use aCircular Through-Shaped Resonator for obtaining power combination using active elements at frequency region Δf≈20–40 GHz. The resonator is formed by two plane aluminum reflectors. The first reflector has a circular groove. The second reflector has coupling elements. The first and the second reflectors are considered as a ring groove shaped waveguide. A resonator spectrum was calculated and analyzed in the frequency range Δf ≈20–40 GHz. It is showed that, in the given frequency range the resonator spectrum has a complicated structure and is formed by a series of spectrum lines; a frequency range between the series increases with the frequency increasing. We studied on transmission coefficient of the resonator, frequency shifts of spectrum lines when inserting a thin (t/λ≈0.003) dielectric substrates into the resonator, and also attenuation constants of waves propagating in circular groove (due to losses in metal).     

Fence guide for millimeter waves

A new waveguide, called "fence guide," for millimeter-wave circuitry on a dielectric substrate is described. The structure of the guide, the field distribution, and its characteristics are considered.     

An interconnected 2D-TM EBG structure for millimeter and submillimeter waves

Due to their unique properties, electromagnetic bandgap (EBG) materials are of high interest for applications in communication technology for many frequency bands from microwave up to optical frequencies. We have investigated in both simulation and experiment a two dimensionally periodic EBG structure made by reactive ion etching of silicon with a bandgap for transverse magnetic waves in the millimeter wave range around 100 GHz. The structure comprises both a large bandgap and a high mechanical stability due to interconnecting dielectric bridges.     

Absorption of millimeter to submillimeter waves by atmospheric water molecules

Using the values of the rotational molecular parameters (including cencrifugal distortion terms) of the H₂ ¹⁶O molecule, which can explain 12 observed transitions below 800 GHz, all rotational energy levels with normalized Boltzmann factors larger than 5×10^?8 at 300°K are calculated. Probabilities of all possible electric dipole transitions among these states, 2277 lines, are calculated using the eigenfunctions thus obtained, and the permanent electric dipole moment of 1.8546 Debye. Assuming the single and full Lorentzian line forms, we calculated the absorption coefficient for millimeter to submillimeter region. Our result, using the single term Lorentzian line form, agrees quite well with experiment for 1 Torr of water vapor in 760 Torr air at 300°K.     

Metal mesh couplers using evanescent waves at millimeter and submillimeter wavelengths

In this paper we introduce a metal mesh evanescent wave coupler that makes use of evanescent wave coupling between a metal mesh and a dielectric plate, as a quasi-optical component for millimeter and submillimeter wavelengths. The transmission properties of this type of couplers have been investigated experimentally and theoretically for both capacitive and inductive metal meshes in the frequency range from 40 GHz to 60 GHz. The transmittance of a capacitive metal mesh evanescent wave coupler can be adjusted more than 70% by changing the spacing between the capacitive mesh and the silicon plate less than 0.15 mm at around 57 GHz.     

Frequency multipliers for millimeter and submillimeter wavelengths

Theory and tools for analysis and design of millimeter- and submillimeter-wave multipliers are discussed. Experimental work is reviewed. The Schottky diode model at submillimeter frequencies, use of Schottky multiplier chains versus direct higher-order multipliers, and the effect of cooling on Schottky diode multipliers are discussed. Alternative diodes such as the high electron mobility varactor (HEMV), the barrier-intrinsic-n⁺ diode (BIN), the barrier-n-n⁺ diode (BNN), the quantum well diode (QWD), and the single barrier varactor (SBV) are discussed, with attention given to their potential submillimeter frequency multipliers     

A new leaky wave antenna for millimeter waves using an asymmetric strip in groove guide, Part I: Theory

Traveling wave antennas for the millimeter wave range face two main problems: higher metal loss at the higher frequencies, and fabrication difficulties due to the smaller wavelengths. These two problems are addressed here by a new type of leaky wave antenna, in which the fabrication problem is minimized by employing a longitudinally continuous aperture, and the higher loss reduced by basing the antenna on a low-loss waveguide, the groove guide. A longitudinally continuous asymmetric metal strip provides the mechanism that transforms the initially bound mode into a leaky mode. An accurate analysis, based on a transverse equivalent network, is presented here for the properties of this leaky structure that takes into account the mode conversion from the bound mode to the leaky mode. All the constituents of this transverse equivalent network are obtained in closed form, thus yielding a dispersion relation in closed form. Part I of these two companion papers describes the new antenna and its principle of operation, and then derives the parameters of the complete transverse equivalent network. Part II is concerned with the properties of the leaky mode and their relations to leaky wave antenna performance; design considerations together with a variety of numerical results are contained in Part II.     

Transmission characteristics of several kinds of closed groove waveguides for millimeter waves

An advantage of closed groove guide over open groove guide is attended. In this paper, the several kinds of closed groove guides including the trapezoidal-, elliptic- and parabolic-groove guides as new types of millimeter wave transmission lines are presented. Their dispersion and cut-off characteristics of the dominant mode are analysed and compared with ones of the closed V-and circular- groove guides by using the equivalent network method. The obtained results have important meaning in theoretical studies and actual applications of groove waveguides.     

A new leaky wave antenna for millimeter waves using an asymmetric strip in groove guide, Part II: Design considerations

part I of this pair of companion papers describes a new type of leaky wave antenna for millimeter wavelengths and presents derivations of the parameters of the transverse equivalent network that accurately characterizes its leaky wave behavior. From a resonance of this transverse equivalent network, one obtains a dispersion relation in closed form from which numerical values of the leaky wave behavior have been obtained. Part II begins with this dispersion relation and a brief discussion of the numerical procedure employed. The relations between these leaky wave properties and the design of leaky wave antennas form the main concern of Part II. In this context, design aspects are discussed, including optimization considerations and the fact that they are frequency independent, and then a variety of numerical results are presented, together with their relevance to leaky wave antenna performance. It is seen that this antenna is capable of systematic design and is versatile with respect to the scan angle and beamwidth of the radiation.     

Superconducting detectors and mixers for millimeter and submillimeter astrophysics

Superconducting detectors will play an increasingly significant role in astrophysics, especially at millimeter through far-IR wavelengths, where the scientific opportunities include key problems in astronomy and cosmology. Superconducting detectors offer many benefits: outstanding sensitivity, lithographic fabrication, and large array sizes, especially through the recent development of multiplexing techniques. This paper describes the scientific opportunities, the basic physics of these devices, the techniques for radiation coupling, and reviews the recent progress in direct detectors, such as transition-edge bolometers, and the work on tunnel junction (superconductor-insulator-superconductor) and hot-electron mixers.     

Quasi-optical ferrite devices for millimeter and submillimeter wave bands

Main features of the development of quasi-optical ferrite devices, using Faraday effect, are considered. Properties of a polarizing divider and a ferrite rotator of a polarization plane are analysed with standpoint of minimum losses. A matching method, based on an utilization of the rotator element in a form of the multilayers ferrite structure, which can be adjusted independently for right-handed and left-handed cyrcularly polarized waves, is suggested. It is shown, that this method allows to obtain a total matching in a quasi-optical transmission line. Results of an investigation of quasi-optical ferrite devices for the oversized round waveguide withH ₁₁ mode are presented.     

A low noise receiver for millimeter and submillimeter wavelengths

A broadband, low noise heterodyne receiver, suitable for astronomical use, has been built using a Pb alloy superconducting tunnel junction (SIS). The RF coupling is quasioptical via a bowtie antenna on a quartz lens and is accomplished without any tuning elements. In this preliminary version the double sideband receiver noise temperature rises from 205 K at 116 GHz to 375 K at 349 Ghz, and to 815 K at 466 GHz. This is the most versatile and sensitive receiver yet reported for sub-mm wavelengths.     

Dielectric image line groove antennas for millimeter waves, Part II: Experimental verification

In the first part of this paper the theory of radiation from discontinuities in the ground plane of a dielectric image line has been described. In this second part experimental verifications of the radiation theory as well as millimeter-wave antennas realized on the basis of the theory are described. In the antennas slots and holes in the ground plane of the dielectric image line are used as discontinuities. Experimental results for the radiation characteristics are discussed.     

Dielectric image line groove antennas for millimeter waves, Part I: Theoretical background

Dielectric image line groove antennas are very useful for the application in the millimeter-wave region. In this first part of a two-part paper, three different types of groove discontinuities under a dielectric image line for application in millimeterwave antennas are investigated: the equivalent circuits of 1) a slot discontinuity in a metallic ground plane and 2) a slot discontinuity in the metallization of a substrate material under a dielectric image line are derived theoretically using an approximation for the electromagnetic fields of the slots. 3)The equivalent circuit of cylindrical holes in a metallic ground plane under a dielectric image line is derived from measurements. The results are used to synthesize millimeterwave dielectric image line antenna arrays as described in part II of the paper.     

Radar astronomy at millimeter and submillimeter wavelengths

The scant two-decade existence of radar astronomy has seen important contributions by this new technique to positional astronomy, to the metrics of the solar system, and to the study of lunar and planetary surfaces. The role of millimeter wavelengths in this new astronomy is discussed and the problems unique to these short wavelengths defined. Brief mention is made of the importance of correlation of active and passive measurements and important new millimeter wave component requirements are listed. The implementation of an eight-millimeter radar capable of detecting the moon is described. At the eight-millimeter wavelength, the moon is found to be generally rough and has a radar cross section of about seven percent of its projected geometrical area. Methods of improving these measurements and their feasibility are outlined. Future equipment configurations capable of extending millimeter wave measurements can be implemented, given critical component development success.     

Advanced devices and components for the millimeter and submillimeter systems

The purpose of this paper is to discuss key topics related to low-noise mixers, high efficiency multipliers, the use of quasi-optical techniques to reduce circuit losses, and the development of very high-Q devices applicable to the millimeter and submillimeter wavelengths [1]-[5]. In particular, we will describe the development of a highly reliable metalized GaAs Ta-Schottky-barrier diode with native-oxide passivation. The zero-bias cutoff frequency of these diodes is greater than 1000 GHz when measured accurately near 60 GHz with a zero-bias junction capacitance near 0.1 pF. This zero-bias cutoff frequency is approximately twice the value for a comparable nonmetallized device. Using these very high-Q devices, we have achieved RF performance that has advanced prior state of the art. In frequency multipliers, doublers (100-200 GHz), and triplers (100-300 GHz), we have realized conversion efficiencies of 12 and 2 percent, respectively. The CW output power of the doubler was 18 mW and that of the tripler 2 mW. In an image-enhanced mixer at 35 GHz with an IF of 1 GHz, we have realized conversion loss below 3 dB including 0.6-dB circuit losses, and less than 5.9-dB noise figure (SSB) including a 2-dB IF noise-figure contribution.     

Resonator systems for klystrons of millimeter and submillimeter wave bands

Design problems of resonator systems for klystrons of millimeter and submillimeter wave bands are considered. It has been shown that, for efficient interaction of the resonator’s field and the electron beam in such devices, it is necessary to use resonators with high wave impedance. A quality factor, which allows one to compare resonators having different shapes, has been introduced. Different means of increasing the resonator’s wave impedance and circuits coupling resonators to input and output transmission lines have been investigated.     

A bulk semiconductor imaging device for millimeter and submillimeter radiation

A device is described whereby millimeter or submillimeter wave images obtained from reflecting targets can be converted to visible displays providing a cathode ray tube presentation. The principle of the technique is based on the fact that transmitted power at these wavelengths can be modulated by a semiconductor panel in which the bulk conductivity is changed by electronic means. Experimental data is reported.