A Novel Low-Loss Dielectric Waveguide for Millimeter and Submillimeter Wavelengths

This paper describes a novel dielectric (gas confined) wave guide which consists of a thin dielectric tube separating an internal high-dielectric-constant gas from an external low-dielectric-constant gas. The attenuation constant, fractional power flow, and radiation Ioss of this waveguide are calculated and compared with those of a conventional O-guide (a dieletric tube waveguide). The advantage of the gas-confined guide is that the attenuation constant is decreased involving no bending loss increase due to tight field confinement within the low-loss internal gas. Experimental investigations are carried out to verify the low-loss property of the gas-confined guide. An attenuation constant less than 0.4 dB/m is obtained over the 80-200-GHz range.     

A Proposal of Low-Loss Leaky Waveguide for Submillimeter Waves Transmission

A low-loss dielectric leaky waveguide which carries most of the power in air is proposed for long-distance transmission of submillimeter waves, and its guiding mechanism is fully analyzed by using a two-dimensional slab-waveguide model. It is shown that transmission losses of the guide can become several decibels per kilometer and are not significantly affected by dielectric losses of material used for practical guide parameters.     

Anomalous Low-Loss Transmission in a Gas-Confined Dielectric Waveguide for Millimeter and Submillimeter Wavelengths

A novel low-loss (gas-confined) dielectric waveguide for millimeter and submillimeter wavelengths was previously reported by the author. The waveguide consists of a thin dielectric tube separating an internal high-dielectric-constant gas from an external low-dielectric-constant gas. The attenuation constant of this form of waveguide usually increases with increasing tube thickness. The thick tube is indispensable for a mechanically stable waveguide. In this paper, anomalous low-loss transmission characteristics in a gas-confined dielectric waveguide with a thick tube are described. Some condtions are theoretically found where the attenuation constant of the waveguide with a thick tube is extremely low, due to tight field confinement within the internal gas. A qualitative explanation of the operation mechanism is also given.     

Impedance Characteristics of Closed Elliptic-Groove Waveguide for Millimeter Waves

A characteristic equation and impedance characteristic for the dominant mode of closed elliptic-groove guide have been analyzed and discussed by using the mode-matching method. The reference size of the closed elliptic-groove guide for the good impedance matching with rectangular guide in actual application is given. The obtained conclusions are of important significance in theoretical studies and actual applications of closed elliptic-groove guide for millimeter waves.     

Analysis for Transmission Properties of Arbitrarily Trapezoidal-Groove Waveguide for Millimeter Waves

In this paper, the transmission properties such as the dispersion and attenuation characteristics for the dominant mode of the trapezoidal-groove waveguide with arbitrarily inclined angle are analyzed and discussed by using the mode-matching method. Some calculated results are in very good agreement with the published data. The obtained conclusions are of important significance in theoretical studies and actual applications of trapezoidal-groove waveguides for millimeter and submillimeter waves.     

Transmission Properties of Closed Trapezoidal-Groove Guide for Millimeter Waves

The transmission characteristics of the mode TE₁₁ for a new type of closed trapezoidal-groove guide with arbitrary inclined angle are analysed in detail with the mode-matching method in this paper. The calculated results are in good agreement with the experimental values in the published reference. The dispersion of the closed trapezoidal-groove guide is very low. The relationships of the cut-off wavelength and the attenuation constant with the structural sizes of the closed trapezoidal-groove waveguide are also obtained. The given results have very important value in study, design, manufacture and application for closed trapezoidal-groove waveguide.     

Bragg Reflection Characteristics of Millimeter Waves in a Periodically Plasma-Induced Semiconductor Waveguide

Theoretical analysis on the Bragg reflection characteristics of millimeter waves in a periodically plasma-induced semiconductor waveguide is presented. The plasma is assumed to be generated by light illumination. Numerical examples are given which show the dependence of the Bragg reflection characteristics on the length of the plasma-induced section and on the plasma density. Since the period can be changed by altering the illumination pattern, this type of periodic structure may be developed to tunable filters or tunable DBR oscillators for millimeter-wave region.     

Radiation of Millimeter Waves from a Leaky Dielectric Waveguide with a Light-Induced Grating Layer

A theoretical analysis is presented for the radiation characteristics of millimeter waves in a periodic dielectric waveguide having a light-induced grating layer. The waveguide is assumed to be composed of an insulator (sapphire) slab whose one surface is coated with a high-resistivity semiconductor (silicon) film. A boundary-integral-equation formulation is employed to obtain characteristic solutions of the waveguide. Numerical calculations are made at 94 GHz for both TM and TE polarizations. Estimations of the illumination power required to produce the grating are given. The waveguide presented in this paper, in conjunction with a high-power semiconductor diode laser array as a light source, may be developed to operate as an electronically beam-steerable leaky-wave antenna at millimeter-wave frequencies.     

Waveguide Filter on Base of Dielectric the Bragg Structure for Millimeter Waves Applications

It is considered and offered the waveguide band elimination filter with the working mode H₁₀ that can be used in millimeter waves devices such as up, down- converters, mixer, etc. The characteristics of the filter was calculated by using analogy in electromagnetic the waveguide propagation and optical the wave propagation in the medium with the specific refractive index N. This conception can be applied for party-filled waveguide in the case when the Brillouin decomposition of the waveguide waves into plane waves is correct and the transformation of the incident (propagating) mode into other the mode types is absent. In this work were calculated the spectrum energy transmittance T(f) in the filter stop band and the wavelength λ ₀ in the center of this band using the characteristic equation obtained in the result of theoretical consideration. Theoretical results are compared with experimental measurements.     

Mode Distribution and Bandwidth Characteristic of Arbitrarily Trapezoidal-Groove Guide for Millimeter Waves

The modes TE and TM of arbitrarily trapezoidal-groove guide are analyzed by using the mode-matching method. The mode TE₁₁ is the dominant mode of the trapezoidal-groove guide under different conditions. The bandwidth characteristic and the operation condition for the single dominant mode are discussed. The obtained conclusions are of very important significance in theoretical study and practical application of trapeziodal-groove guides for millimeter waves.     

On the Design of Transitions Between a Metal and Inverted Strip Dielectric Waveguide for Millimeter Waves

The results of a study of three types of transitions between the rectangular metal waveguide and the inverted strip guide are reported. Reflected power measurements from each type of transition and insertion-loss measurements for configurations involving the three transitions have also been carried out. The procedure of determining the optimum parameters for the transition is quite general, and has the potential for being extended to other dielectric structures.     

The Open-Ring Line: A Low-Loss Surface Waveguide

This paper presents the theoretical analysis of the electromagnetic properties of the open-ring line by means of the Hankel transform. Fields components, stored energy, power flow, dispersion relation, and energy distribution are calculated. Measurements have corroborated our theoretical results. These results help in the design of low-loss line operating in the fundamental dipolar hybrid mode. The measured attenuation on a prototype line consisting of equally spaced aluminum rings held by a metal rod is less than 5 dB/km below 1.8 GHz. Among the possible applications are railway traffic control and railway obstacle detection.     

Birefringent Filter for Millimeter Waves

A scale model (f/sub 0/ =20 GH/sub z/ of a Solc-type birefringent wave filter for millimeter wavelengths is described. The filter consists of five cascaded identical half-wave plates, or crystals, each composed of an artificial anisotropic dielectric medium with its reference axis tilted at some prescribed angle to the plane of the input polarization. The design and analysis of an individual plate, using Collin's second-order theory of the birefringence of artificial anisotropic dielectrics, and the analysis of multielement filters (filters composed of many plates), aided by Evans' matrix method, are discussed. The experimental filter was tested in the range of 18 to 33 GHz, and its measured performance was found to compare well with the theoretical performance over a major portion of the range of frequencies used in the tests. A synthesis procedure for optimum (equal-ripple stopband) response multielement filters is given, together with tables of plate angles for such filters. In this procedure, the Dolph approximation and the Harris synthesis are combined.     

Channel Multiplexing Network for a Millimeter Waveguide Transmission System

The Nippon Telegraph and Telephone Public Corporation (NTT) plans to make a field test for the practical application of the W-40G millimeter waveguide transmission system, using a frequency range of 43 GHz to 87 GHz and a clock frequency of 403 MBd. This paper describes channel multiplexing-demultiplexing networks fabricated for use in the test. First, frequency allocation and construction of the 43 ∼ 87 GHz multiplexing-demultiplexing networks are discussed. Second, newly developed hardware consisting of band-splitting filters and channel-dropping filters is described. Finally, overall loss, frequency response in amplitude and delay and pulse waveform transmission characteristics are shown. The overall losses of the networks constructed by three stages, namely, band-splitting filters (I), (II), and a channel-dropping filter, are 8 ∼ 12 dB over the frequency range from 43 GHz to 87 GHz, with the channel-dropping filters only partly installed. The experimental results suggest that these multiplexing-demultiplexing networks are suitable for the millimeter wave guided wave communication system.     

Measurement of Dielectric Properties for Low-Loss Materials at Millimeter Wavelengths

We describe here a system for accurate measurement of the dielectric properties of very low-loss materials in the 130 to 170 GHz frequency range. This system utilizes an open resonator with a quality factor ∼ 1 × 10⁶. Resonance curves for this resonator are acquired with a commercial spectrum analyzer equipped with an external millimeter-wave harmonic mixer. The excitation source is a backward-wave oscillator locked to the spectrum analyzer local oscillator via a digital phase-locked loop. This system permits rapid and accurate measurement of resonance curve line widths, permitting determination of loss tangents down to the 10^-6 range. Results are reported for silicon carbide (SiC), CVD diamond, sapphire, and quartz.     

The Analysis of Hole-Gap Helical Groove Waveguide

The hole-gap helical groove waveguide, as a all-metal slow-wave circuit, has advantages of good heat dissipation and great size, and thus is suitable for use of mm TWT. By means of an approximate field theory, the expressions of the dispersion equation and the coupling impedance of the hole-gap helical groove waveguide is obtained in this paper. The influence of various circuit dimensions on the dispersion relation and the coupling impedance is discussed by the numerical computation.     

A New Leaky Waveguide for Millimeter Waves Using Nonradiative Dielectric (NRD) Waveguide-Part I: Accurate Theory

An almost-rigorous analysis is presented for a new leaky waveguide of simple configuration based on a recent nonradiative modification of H guide suitable for millimeter wavelengths, The analysis employs a transverse equivalent network that yields a dispersion relation in closed form, and contains some interesting and subtle features. Numerical values are presented for the phase and leakage constants in terms of the different geometric parameters and the dielectric constant comparisons with measurements are made in the companion paper, part II.     

Hollow-Cylinder Waveguide Isolators for Use at Millimeter Wavelengths

The device considered in this study is a semiconductor waveguide isolator consisting of a hollow column of a semiconductor mounted coaxially in a circular waveguide in a longitudinal dc magnetic field. An elementary and physical analysis based on the excitation of plane waves in the guide and a more rigorous mode-matching analysis (MMA) are presented. These theoretical predictions are compared with experimental results for an InSb isolator at 94 GHz and 7.5 K.