€\PAPERS, REPORTS
- "Submillimeter Guided-Wave Experiments with Polyethylene Slab Waveguides,"
M. Tsuji, K. Kawai, H. Shigesawa, K. Takiyama, IEEE Transactions on Microwave Theory and Techniques, vol.27, no.11, pp.873-878, Nov. 1979.
- Abstract: The attenuation constants of a symmetric polyethylene slab waveguide are
measured in the submillimeter-wave region at lambda0= 337 mu m. In our experiments the fine metal grating is used as a coupler, instead of a usual prism coupler. Our coupler which is different from the conventional grating coupler fixed on a slab is easily movable along a slab without a fluctuation in the coupling efficiency, and the loss measurement is successfully performed for several kinds of slab thicknesses by using such couplers. As a result, the attenuation constant of about 1.3 dB/m is measured, in good reliability, for a slab of 10 mu m in thickness. Finally, to make clear the accuracy of our loss measurements, the transverse broadening of the field along the propagating direction of a slab is measured experimental!y, and it is concluded that there is little influence of the transverse broadening on the measured attenuation constants.
- "Submillimeter Guided-Wave Experiments with Dielectric Rib Waveguides,"
M. Tsuji, S. Suhara, H. Shigesawa, K. Takiyama, IEEE Transactions on Microwave Theory and Techniques, vol.29, no.6, pp.547-552, Jun. 1981.
- Abstract: The transmission characteristics of rib waveguides are examined in the
submillimeter-wave region at Lambda0 =337 Κm. A number of miniature polyethylene rib waveguides are fabricated by means of a die-cast technique. The mode launching into such a waveguide is performed by focusing a laser beam directly on the end face of the waveguide, while the transmitted power is detected at any point on a waveguide through a movable grating coupler which can couple selectively with one of propagating modes. The measured phase constants show good agreement with the theoretical ones calculated by our analytical method, while the attenuation constants, typicafly alpha lambda 0 = 4.5 X 10-3 are found to be about 1.8 times as much as theoretical ones. Finally, the good confinement of fields in the rib portion is proved by means of two simple methods.
- "Analytical and Experimental Considerations on the Resonant Frequency
and the Quality Factor of Dielectric Resonators," M. Tsuji, H. Shigesawa,
H. Aoki, K. Takiyama, IEEE Transactions on Microwave Theory and Techniques, vol.30, no.11, pp.1952-1958, Nov. 1982.
- Abstract: A dielectric pillbox resonator placed on a dielectric substrate is analyzed by a new method, the approximate mode matching method, in which the cross section of such a resonator is subdivided into several sub-sections having a simple geometry of the boundaries, i.e., dielectric slab radial waveguides, and the continuity condition of fields between subsections is treated in the least-squares sense. The resonant frequencies and the intrinsic Q values due to the leakage loss through the dielectric substrate calculated by this method are presented together with experimental results obtained in the 50-GHz region. As a result, it is found that the experimental results for both the resonant frequencies and the Q values agree better with our calculated ones than with the results by other approximate method, and so it will be concluded that the analytical method presented here is almost enough to discuss precisely the resonant characteristics of a dielectric pillbox resonator.
- "On the Complex Resonant Frequency of Open Dielectric Resonators,"
M. Tsuji, H. Shigesawa, K. Takiyama, IEEE Transactions on Microwave Theory and Techniques, vol.31, no.5, pp.392,396, May 1983.
- Abstract: An analytical method is presented for calculating accurately the complex resonant frequency of dielectric pillbox resonators. In this method, an approximated field of the resonator is expanded into a truncated series of solutions of the Hehnholtz equation in the spherical coordinates, and the boundary condtion on the resonator surface is treated in the least-squares sense. The resonant frequency and the intrinsic Q value due to radiation loss are obtained in the form of approximation converging to the exact values. Numericaf results are compared with previously published calculations, which show that the present method is a relatively simple and effective one.
- "Guided-Wave Experiments with Dielectric Waveguides Having Finite
Periodic Corrugation," M. Tsuji, S. Matsumoto, H. Shigesawa, K. Takiyama,
IEEE Transactions on Microwave Theory and Techniques, vol.31, no.4, pp.337-344, Apr. 1983.
- Abstract: A planar dielectric waveguide having finite periodic rectangular corrugation
is investigated analytically and experimentally, in case of surface waves
propagating at an angle to the corrugation. In analytical considerations,
a finitely corrugated guide is regarded as consisting of many step discontinuities
connected by a length of uniform slab waveguide, and its propagation characteristics
in the Bragg interaction region are derived from a cascaded connection
of the transmission matrix expressing a step discontinuity. Although the
present method takes only surface wave modes into account and neglects
the wave with continuous spectrum, the calculated results show an excellent
agreement with experimental ones which are performed for art H-guide in
the microwave region.
- "Analytical and Experimental Investigations on Several Resonant Modes
in Open Dielectric Resonators," M. Tsuji, H. Shigesawa, K. Takiyama,
IEEE Transactions on Microwave Theory and Techniques, vol.32, no.6, pp.628-633, Jun. 1984.
- Abstract: The complex resonant frequency of open dielectic pillbox resonators is
analyzed by an analytical method proposed by the present authors, which
expands the field into a truncated series of solutions of the Hehnholtz
equation in the spherical coordinates and treats the boundary condition
in the least-squares sense. This method is applied to calculate the characteristics
of several resonant modes which will be of practical use. The accuracy
of the method is confirmed by investigating the convergence of solutions.
Also, numerical results are compared with experimental results of several
resonant modes, which are obtained for the dielectric samples with epsilonr= 38.0 and 19.5 in the X-band.
- "Mode Propagation through a Step Discontinuity in Dielectric Planar
Waveguide," H. Shigesawa, M. Tsuji, IEEE Transactions on Microwave Theory and Techniques, vol.34, no.2, pp.205-212, Feb. 1986.
- Abstract: This paper presents two methods for dealing with wave propagation through
a dielectric step discontinuity at normal incidence. One method helps to
accelerate the convergence of solutions, especially for the TM-mode problem,
and the other treats efficiently the continuous mode spectrum by introducing
the Legendre transform in the case of open waveguides. As for the former,
the singular fields around the dielectric edges are introduced in terms
of direct use of their functional forms to the boundary condition, which
is fulfilled in the sense of least squares. As for the latter, the expansion
in terms of the Legendre functions is performed for optimally divided ranges
of a continuous spectrum. A number of numerical examples prove that the
methods presented herein are quite powerful for solving the TM-mode discontinuity
problems in dielectric waveguides of both closed and open types.
- "A Completely Theoretical Design Method of Dielectric Image Guide
Gratings in the Bragg Reflection Region," H. Shigesawa, M. Tsuji,
IEEE Transactions on Microwave Theory and Techniques, vol.34, no.4, pp.420-426, Apr. 1986.
- Abstract: This paper presents a new and completely theoretical accurate method for
the design of dlelectic image guide gratings. Our method is based on a
network approach that can easily analyze, with satisfactory approximations,
the interaction of dielectric step discontinuities. These are the fundamental
constituents of our gratings. Measurements on a filter modeled at X-band
show excellent agreement with the design characteristics.
- "Two-path cutoff waveguide dielectric resonator filters," H.
Shigesawa, M. Tsuji, T. Nakao, K. Takiyama, IEEE Transactions onMicrowave Theory and Techniques, vol.37, no.7, pp.1105-1112, Jul. 1989.
- Abstract: The authors propose an evanescent-mode wave-guide filter consisting of
two parallel cutoff waveguide paths with dielectric resonators. They introduce
an accurate design method incorporating both the full-wave analytical method
and the impedance inverter method. The specified overall characteristic
is then synthesized with the help of a computer-aided design method. Measurements
on several kinds of filters modeled at X-band show excellent agreement with the designed characteristics.
- "A new equivalent network method for analyzing discontinuity properties
of open dielectric waveguides," H. Shigesawa, M. Tsuji, IEEE Transactions on Microwave Theory and Techniques, vol.37, no.1, pp.3-14, Jan. 1989.
- Abstract: A novel network approach is proposed for analyzing interacting discontinuities on open planar dielectric waveguides by accurately taking account of both surface modes and waves with continuous spectra. In this approach, a continuum of the radiation wave is recomposed into a set of the newly defined spectral composite modes, each of which carries a finite magnitude of radiation power. These new modes, in conjunction with surface modes, construct the complete orthonormal set for expressing an arbitrary local field on a dielectric slab waveguide. This leads to an equivalent network approach effective for solving discontinuity problems, even on an open waveguide using the conventional method for closed-waveguide problems. A number of numerical results are shown to demonstrate the usefulness of the proposed approach.
- "New interesting leakage behavior on coplanar waveguides of finite
and infinite widths," M. Tsuji, H. Shigesawa, A. A. Oliner, IEEE Transactions on Microwave Theory and Techniques, vol.39, no.12, pp.2130-2137, Dec. 1991.
- Abstract: Above a critical frequency, the dominant mode on coplanar waveguide leaks power in the form of a surface wave on the surrounding substrate, causing undesirable crosstalk and unexpected package effects. Studies revealing several interesting behavioral features are discussed. The features are the conditions under which the leakage rate is strong or weak, the significant modifications in leakage behavior that occur when the CPW width changes from finite to infinite, and the presence of unexpected sharp minima (cancellation effects) in the leakage rate.
- "Low-loss design method for a planar dielectric-waveguide branch:
effect of a taper of serpentine shape," M. Tsuji, O. Tanaka, H. Shigesawa,
IEEE Transactions on Microwave Theory and Techniques, vol.39, no.1, pp.6-13, Jan. 1991.
- Abstract: A design method is proposed for a planar dielectric waveguide Y branch
with low loss caused by radiation. In contrast to the usual design methods,
in which the generation of the radiation wave is kept as small as possible,
the present method positively uses, for the first time, the behavior of
such a radiation wave. The radiation wave at any local position along a
taper section of the Y branch is intentionally generated, and its power
conversion and reconversion with the surface-wave mode are controlled to
reduce the insertion loss for the surface-wave mode. A design example shows
that the low-loss Y branch should have a serpentine-shaped taper, which
is an unexpected shape compared to the usual design. The effectiveness
of the design method presented is confirmed by comparing the numerical
results with those of the usual types of Y branches and with measurements.
- "The feature of the narrow-pulse transmission on conventional coplanar
waveguides when power leakage is present," M. Tsuji, M. Taniguchi,
H. Shigesawa, IEEE Transactions on Microwave Theory and Techniques, vol.41, no.6, pp.1017-1023, Jun./Jul. 1993.
- Abstract: A new type of pulse-shape degradation that occurs when a narrow pulse
is transmitted on conventional coplanar waveguide (CPW) is reported. This
degradation is not caused by the well-known dispersion of the phase constant
of the CPW dominant mode, but by the complicated dispersion behavior of
its attenuation constant due to the leakage effect. This type of degradation
was investigated with two kinds of pulse having different half-power widths.
The power leakage associated with propagation of a narrow pulse also causes
dynamic power coupling with neighboring circuits, which the authors investigate
theoretically and experimentally.
- "Packaging of printed-circuit lines: a dangerous cause for narrow
pulse distortion," M. Tsuji, H. Shigesawa, IEEE Transactions on Microwave Theory and Techniques, vol.42, no.9, pp.1784-1790, Sep. 1994.
- Abstract: We report here a new behavioral feature of a narrow pulse transmitted
on coplanar waveguide (CPW), putting the special stress on the effects
caused by the packaging of such a waveguide. This feature occurs due to
the unexpected simultaneous combination of a distortion in the guided main
pulse and a production of delayed echo pulses. An explanation based on
a new class of the dominant-mode power-leakage effect leads to a clear
physical understanding of why such features necessarily appear.
- "Coupling between different leaky-mode types in stub-loaded leaky
waveguides," H. Shigesawa, M. Tsuji, P. Lampariello, F. Frezza, A.
A. Oliner, IEEE Transactions on Microwave Theory and Techniques, vol.42, no.8, pp.1548-1560, Aug. 1994.
- Abstract: Several leaky-wave antennas have been described in recent years that possess
excellent properties, and they all have in common a parallel-plate stub
guide of finite height as part of the cross section. For taller stubs and
for larger leakage rates (wider radiated beams), some interesting new exotic
interactions occur due to coupling between the desired leaky mode and another
leaky mode, which is a modification of the gchannel-guideh mode. Although
we have described such coupling behavior briefly previously, this basic
new feature (the coupling between two leaky (complex) modes) is not generally
known, and is discussed here in more detail and in a more general context.
In addition to a broad qualitative discussion, numerical results are presented
for structures based on NRD guide and on stub-loaded rectangular guide.
We believe that these effects are universal to all leaky-wave structures
that possess a finite stub height in the cross section, so that the discussion
here serves as a model for what to expect for other structures.
- "Simultaneous propagation of bound and leaky dominant modes on printed-circuit
lines: a new general effect," H. Shigesawa, M. Tsuji, A. A. Oliner,
IEEE Transactions on Microwave Theory and Techniques, vol.43, no.12, pp.3007-3019, Dec. 1995.
- Abstract: We were the first to report that both the bound and leaky dominant modes
can propagate simultaneously on conductor-backed coplanar strips over a
frequency range. We have recently studied this interesting and initially
unexpected effect in more detail, and we have made two important discoveries:
First, the simultaneous-propagation effect can actually occur on most,
if not all, printed-circuit transmission lines (its presence depending
on the relative line dimensions), so that, contrary to earlier belief,
the effect is rather general. Second, we have discovered the surprising
presence of a new improper (or nonspectral) real solution, which is nonphysical
but whose evolution as a function of dimensional change serves to explain
how the simultaneous-propagation effect can occur. The new solution, and
its behavior in a completely nonphysical region, thus governs otherwise-mysterious
large changes in the physical, measurable solutions.
- "A versatile leaky-wave antenna based on stub-loaded rectangular waveguide
.III. Comparisons with measurements," M. Tsuji, H. Shigesawa, F. Frezza,
P. Lampariello, A. A. Oliner, IEEE Transactions on Antennas and Propagation, vol.46, no.7, pp.1047-1055, Jul. 1998.
- Abstract: For pt.II ibid., vol.46, no.7, p.1042-46. The article describes the measurements
that verify the validity of the theoretical expressions for this new type
of antenna. Measurements were made both at millimeter wavelengths (40 to
60 GHz) and in the X-band (8 to 12 GHz) frequency range and of two different
quantities: the propagation wavenumbers ΐ and Ώ and radiation patterns.
Comparisons were made with numerical values obtained from the theoretical
expressions derived in parts I and II and very good agreement was found
in all cases.
- "A versatile leaky-wave antenna based on stub-loaded rectangular waveguide
.II. Effects of flanges and finite stub length," F. Frezza, P. Lampariello,
H. Shigesawa, M. Tsuji, A. A. Oliner, IEEE Transactions on Antennas and Propagation, vol.46, no.7, pp.1042,1046, Jul. 1998.
- Abstract: For pt.I see ibid., vol.46, no.7, p.1032-41 (1998). A new leaky-wave antenna was presented and discussed in Part I that possesses many desirable performance features. The antenna structure is also simple in form, consisting of a rectangular waveguide with an offcenter stub on its top wall. Part I presented the principle of operation and the basic theory in which the stub guide was idealized to be infinitely long (or high) in order to stress the essential features. In practice, however, the stub guide has a finite length (or height) and it may be terminated by a flange or a ground plane or simply remain in the form of a pair of baffles. The modifications in the theory and the associated performance considerations under these practical circumstances are treated in this paper.
- "A versatile leaky-wave antenna based on stub-loaded rectangular waveguide
.I. Theory," P. Lampariello, F. Frezza, H. Shigesawa, M. Tsuji, A.
A. Oliner, IEEE Transactions on Antennas and Propagation, vol.46, no.7, pp.1032-1041, Jul. 1998.
- Abstract: A new leaky-wave antenna is presented that possesses many desirable features
and is suitable for application to both the millimeter-wave and microwave
ranges. These desirable features, some of which are unusual, include a
simple configuration, a wide flexibility in the range of available beamwidths,
the ability to control the beamwidth and the direction of the beam essentially
independently, and negligible cross polarization at all scan angles. The
antenna structure consists of a parallel-plate stub guide of small height,
less than a half wavelength, located off center on the top of rectangular
waveguide. The beamwidth is easily controlled from very wide to very narrow
by adjusting the stub width or location. The article presents the principle
of operation and the theory, employing a new transverse equivalent network
that is accurate, but also simple, so that it permits rapid and inexpensive
numerical calculations.
- "Significant contribution of improper-real solution to the fields
excited by a practical source in printed-circuit transmission lines,"
M. Tsuji, N. Yahata, H. Shigesawa, IEEE Transactions on Microwave Theory and Techniques, vol.47, no.12, pp.2487-2492, Dec. 1999.
- Abstract: For conductor-backed coplanar strips, we first reported that nonphysical
improper solution has a significant effect on the physical total field
excited by a practical source. Here, we quantitatively and experimentally
investigate this unexpected effect for slot lines in more detail, and we
conclude that it occurs on most, if not all, printed-circuit lines; thus,
the effect is rather general.