Tsukasa Yoneyama

Design of Nonradiative Dielectric Waveguide Filters (Short Papers)

An efficient design technique of nonradiative dielectric waveguide filters for use at millimeter wavelengths is developed. Filter stuctures considered here are a gap-coupled type and an altenating-width type. According to present theory, 3-pole, 0.1-dB Chebyshev ripple bandpass filters with a 2-percent bandwidth at a center frequency of 49.5 GHz were designed and fabricated with Teflon dielectric. Calculated and measured filter responses agree quite well, and excess insertion losses are found to be as small as 0.3 dB for both types of the fabricated filter circuits.

Nonradiative dielectric waveguide circuit components

The nonradiative dielectric waveguide (NRD-guide) is a newly proposed dielectric waveguide which can substantially suppress radiation at curved sections and discontinuities and is applicable to great advantage for millimeter wave integrated circuits. Basic circuit components such as transitions between a metal waveguide and an NRD-guide, matched terminations, a ring resonator and a bandpass filter were fabricated with polystyrene material and tested successfully at 50 GHz. Measurements showed that each component worked as expected without suffering from undesirable radiation and interferences at all.

Reflection and transmission of Rayleigh waves by the edge of a deposited thin film

The reflection and transmission of Rayleigh waves by the edge of an isotropic thin film deposited on an isotropic substrate is solved within the first‐order approximation relying on the Wiener‐Hopf technique under the assumption that the film is thin enough compared to the wavelength. Straight‐crested Rayleigh waves are assumed to impinge on the edge of the film perpendicularly from the unplated side of the substrate. In formulating the problem mathematically, Tierstens boundary condition is employed to take into account the effects which the deposited film imposes on the elastic waves in the substrate. Expressions for the radiation coefficients of both of the bulk waves, longitudinal and transverse, and for the reflection coefficient of the Rayleigh wave are derived and evaluated numerically for gold, aluminum, nickel, and copper films deposited on the fused‐silica substrate. It is found that the radiation coefficients, especially the one for the transverse bulk wave, exceed the reflection coefficient b...

A 60-GHz optical frequency shifter using coupled inverted slot lines

A millimeter-wave optical frequency shifter (OFS) using coupled inverted slot lines (ISLs) is integrated on an X-cut LiNbO/sub 3/ substrate, Theoretical analysis shows that the use of the coupled ISLs makes it possible to decrease the distance between the arms of a Mach-Zehnder interferometer for optical frequency shifting. The ISL coupling characteristics measured at 60 GHz coincide well with the calculated ones. A 60-GHz frequency shifting of a 1.3-/spl mu/m optical carrier is experimentally demonstrated using two- and four-branch OFSs. The theoretical analysis and experimental results of the two-branch OFS show that the ratio of the frequency-shifted signal intensity to the optical image intensity is in proportion to the difference between the applied dc-bias voltage and the half-wave voltage. The four-branch OFS consists of two two-branch OFSs excited 180/spl deg/ out of phase, and can suppress the optical image and original carrier simultaneously. The measurements of the four-branch OFS reveal the optical image suppression of over 12 dB and the original carrier suppression of 5 dB below the desired 60-GHz frequency-shifted signal.

Millimeter-wave research activities in Japan

This paper is intended to give an insight into millimeter wave research activities in Japan particularly to participants from abroad. Quasigovernmental and academic organizations for promoting millimeter wave research and development are described. Then, state-of-the-art millimeter wave techniques such as MMICs, low cost production module techniques and MCM techniques are presented. The NRD-guide technology is also a topic to be discussed, since it has seen a new development toward practical applications. Though many millimeter wave applications systems have been proposed so far, indoor LANs and car collision avoidance radars seem to be near commercial availability. Another millimeter wave application technology is millimeter wave photonics which can be a key technology for millimeter wave mobile communications in the near future.

Velocity-matched LiNbO/sub 3/ waveguide optical modulator using inverted slot line

An inverted slotline (ISL) was used to achieve velocity matching in a Ti-diffused LiNbO/sub 3/ waveguide optical modulator. Phase modulation of 1.38 radian could be observed at an optical wavelength of 0.63 mu m with 100-mW microwave power around 10 GHz. This ISL optical modulator is expected to operate at millimeter wavelengths.<<ETX>>

Planar millimeter-wave car warning radar using NRD-guide

The development of a 60 GHz FM-CW car warning radar by integrating NRD-guide front-end with the planar slot array antenna is described. The structure of the radar-head is planar with 150 mm in vertical length, 140 mm in width and 19 mm in thickness. The results of experiments show that the measured distance error is less than 0.7 m for the target distance between 5 m to 120 m, satisfying the car radar specifications issued by the Ministry of Posts and Telecommunications.

A Systematic Investigation on Diffraction Characteristics of Dielectric Periodic Structure with Arbitrary Grating Profiles

Wave diffraction characteristics of dielectric periodic structures with arbitrary grating profiles are systematically investigated for TE and TM mode polarization by an effective engineering method, which combines the staircase approximation with the rigorous mode matching procedure. The variations of the diffraction with the frequency and incident angle for the periodic structures with different grating profiles, such as rectangle, sinusoid, triangle, trapezoid, increasing cosine, semi-ellipse and semi-circle are systematically and comparatively studied. The effectiveness and accuracy of the present method are verified by the results given in the literature.

Laterally shielded coplanar waveguide for millimeter waves

A laterally shielded coplanar waveguide (CPW) has been proposed for millimeter wave use. It is a CPW sandwiched vertically in a below cutoff parallel plate waveguide and can suppress unwanted waves in circuits. A right angle bend as well as a straight portion of the laterally shielded CPW exhibited excellent performance.<<ETX>>

Inverted Slot Line For Millimeter-Wave Optical Modulator

The inverted slot line is proposed with the pur-pose of applying to optical modulators operating at millimeter-wavelengths. Velocity of millimeter-waves can be matched to that of optical waves in LiNbO3 material by simply adjusting the spacing between th6 slotted surface and the ground plane.