Underfill materials are used in a packaging of millimeter wave IC. However, there are few reports for dielectric properties of underfill materials in millimeter wave region. A cut-off circular waveguide method is one of a powerful technique to evaluate precisely complex permittivity in millimeter wave region. This method may be useful not only for low-loss materials, but also for mid-loss ones with loss tangent of 10$^{-2}$ order. In this paper, an evaluation technique based on the cut-off circular waveguide method is presented to measure mid-loss underfill materials. As a result, the relative permittivity $arepsilon_{r}$ and the loss tangent tan$delta$ are in the range of 2.8$sim $3.4 and (1.0$sim$1.6)$ imes10^{-2}$, respectively. Also, the measurement precision is 2.3% for $arepsilon_{r} approx 3$ and 40% for tan$delta approx 10^{-2}$.

Recently, we proposed a weak-form discretization scheme to derive second-order difference equations from the governing equation of the scattering problem. In this paper, under the scope of the proposed scheme, numerical expressions for the waveguide boundary conditions are derived as perfectly absorbing conditions for input and output ports. The waveguide boundary conditions play an important role in extracting the quasi-localized wave as an eigenstate with a complex eigenvalue. The wave-number dependence of the resonance curve in Fano resonance is reproduced by using a semi-analytic model that is developed on the basis of the phase change relevant to the S-matrix. The reproduction confirms that the eigenstate with a complex eigenvalue does cause the observed Fano resonance.

A new wavelength-selective optical modulator was proposed and discussed. The modulator consists of three kinds of distributed Bragg reflectors (DBRs) integrated in a single straight waveguide. The waveguide can guide TE$_0$ and TE$_1$ modes, and an in-line Michelson interferometer is constructed by the three DBRs. An operation-wavelength wave among incident wavelength-division-multiplexed TE$_1$ guided waves is split into TE$_0$ and TE$_1$ guided waves by one of DBRs, and combined by the same DBR to be TE$_0$ output wave with interference after one of waves is phase-modulated. A modulator using an electro-optic (EO) polymer is designed, and the static performance was predicted theoretically. An operation principle was confirmed experimentally by a prototype device utilizing a thermo-optic effect instead of the EO effect.

In this paper, the function expansion based topology optimization is employed to the automatic optimization of the waveguide dispersion property, and the optimum design of low-dispersion slow-light photonic crystal waveguides is demonstrated. In order to realize low-dispersion and large group index, an objective function to be optimized is expressed by the weighted sum of the objective functions for the desired group index and the low-dispersion property, and weighting coefficients are updated through the optimization process.

This paper presents a 120-GHz-band amplifier module with a hermetic sealing structure for a broadband wireless system. The sealing structure for F-band waveguides is a laminate composed of two sealing plates and a spacer. Each sealing plate has a fused glass window and separates inside air from the ambient atmosphere. The design process of the sealing structure is simple and has good simulation fidelity. The hermetic sealing structure designed for an amplifier in a 120-GHz-band wireless link has an insertion loss of less than 1dB and a return loss of more than 15dB in the operating band. We made three kinds of sealed modules to evaluate the sealing function. The modules sealed with this technique meet the hermetic-seal standard in MIL-STD-883F. We then verified that the sealing structure on the sealed modules has a small enough effect for the transmittance of the intrinsic characteristics. In addition, we performed 10-Gbit/s data transmission using a sealed amplifier module with the bit error rate of less than 10-10.

Optical processing of optical labels is expected for increasing processing speed in network routers. We previously proposed optical waveguide circuits for recognition of optical QAM codes by detecting a null output port. The circuits are based on a recognition circuit for QPSK codes. In the device, however, optical or electrical inverters with large dynamic range are required. In this paper, we propose optical circuits to recognize optical QAM codes by maximum output with a post-processor consisting of thresholders and logical circuits. The recognition function of the waveguide circuit is numerically proved by FD BPM.

A 16×16-element corporate-feed waveguide slot array antenna in the 60-GHz band is designed to achieve broadband reflection and high antenna efficiency. The sub-arrays consisting of 2×2-elements are designed to improve the reflection bandwidth by implementing lower Q and triple resonance. The designed antenna is fabricated by diffusion bonding of thin copper plates. A wide reflection bandwidth with VSWR less than 2.0 is obtained over 21.5%, 13.2GHz (54.7-67.8GHz). The measured gain is 32.6dBi and the corresponding antenna efficiency is 76.5%. The broad bandwidth of more than 31.5-dBi gain is realized over 19.2%, 11.9GHz (56.1-68.0GHz). The gain in bandwidth covers the whole of the license-free 60-GHz band (57-66GHz).

The objective of this paper is to extend the dosimetric assessment of 35mm Petri dishes exposed in the standing wave of R18 waveguides operated at 1950MHz for a medium-oil two-layer configuration for cells in monolayer and suspension. The culture medium inside the Petri dish is covered by oil that prevents evaporation and seals the cells below in the medium. The exposure of the cells was analyzed for one suspension-medium configuration, two different suspension-multilayer configurations, and one monolayer-multilayer configuration. The numerical dosimetry is verified by dosimetric temperature measurements. The non-uniformity of the specific absorption rate (SAR) distribution is 30% for monolayer, and 59-75% for suspension configurations. The latter should be taken into account when biological experiment is performed.

As a promising lamination-loss-free fabrication technique, diffusion bonding of etched thin metal plates is used to realize double-layer waveguide slot antennas. Alternating-phase feed is adopted in this paper to reduce the number of laminated plates to simplify fabrication as well as to reduce cost. A 20 × 20-element double-layer waveguide slot antenna with a bottom partially-corporate feed circuit is designed for 39GHz band operation as an example. The adjacent radiating waveguides as well as the 2 × 2 sub-arrays fed in an alternating-phase manner eliminate the need for complete electrical contact in the top layer. However, the feed circuit in the bottom layer has to be completely diffusion-bonded. These two layers are simply assembled by screws. An antenna laminated by only diffusion bonding is also fabricated and evaluated for comparison. The comparison proved that the simply fabricated antenna is comparable in performance to the fully diffusion-bonded one.

We calculated propagation constants of supermodes for two-dimensional two-slab waveguides, with small core gap, using second-order perturbation expansion from gapless slab waveguide system, and compared our results with the existing works. In the perturbation calculation, we used trapezoidal method to calculate the integral over the transverse direction in space and obtained second-order expansion of (core gap)/(core width) for propagation constants. Our result can explain the qualitative relationship between the propagation constants and the gap distance in the neighbor of (core gap)/(core width) being zero.

A point-to-point fixed wireless access (FWA) system with a maximum throughput of 1Gbps has been developed in the 39GHz band. A double-layer plate-laminated waveguide slot array antenna is successfully realized with specific considerations of practical application. The antenna is designed so as to hold the VSWR under 1.5. The antenna input as well as feeding network is configured to reduce the antenna profile as well as the antenna weight. In addition, integrating the antenna into a wireless terminal is taken into account. A shielding wall, whose effectiveness is experimentally demonstrated, is set in the middle of the wireless terminal to achieve the spatial isolation of more than 65dB between two antennas on the H-plane. 30 test antennas are fabricated by diffusion bonding of thin metal plates, to investigate the tolerance and mass-productivity of this process. An aluminum antenna, which has the advantages of light weight and anti-aging, is also fabricated and evaluated with an eye to the future.

We design and fabricate a double-layer hollow-waveguide slot array antenna with wide bandwidth and high antenna efficiency for the 120 GHz band. The antenna is fabricated by diffusion bonding of laminated thin metal plates for high precision and perfect electrical contact. The 1616-element antenna shows more than 70% antenna efficiency over a 13 GHz bandwidth. Furthermore, it realizes error-free data transmission in 2.5 m distance at up to 10 Gbit/s. To our knowledge, this is the first report of the design and fabrication of a high-efficiency wideband planar antenna for the 120 GHz band.

In situ UV-vis. absorption spectra of cytochrome c adsorbed on ITO electrode was observed with slab optical waveguide spectroscopy combining pulse potential step (PPS) between 0.3 and -0.45 V vs. Ag/AgCl. The amount of cytochrome c adsorbed on ITO electrode was estimated from the amount of coulomb of the peaks in cyclic voltammogram to be about a monolayer coverage in this experimental condition. Spectral change between oxidized and reduced cytochrome c by PPS was finished in about 20 msec with phosphate buffer solution. The results strongly proved that SOWG spectroscopy should be effective for in situ observation of ET reaction kinetics of surface adsorbed molecules.

To better understand antenna properties in a narrow space such as in a densely-packed device, a circular microstrip antenna in a narrow parallel-plate waveguide is theoretically studied. An analytical expression is derived for the input impedance in a parallel-plate waveguide by using the cavity model with surface admittance on the side wall. The surface admittance is defined by the external magnetic field due to the equivalent magnetic current at the aperture and takes into account the contribution of the parallel plates to the antenna. The magnetic field external to the antenna, that is in the parallel-plate region, is determined by using a dyadic Green's function. The input impedance is then calculated by a basic definition based on the conservation of the complex power. An analytical expression which couples the resonant frequency and the surface susceptance is also formulated. Presented expressions are validated by comparison with experimental results.

In this paper, we have analyzed the guiding problem by dielectric waveguide with defects composed of dielectric circular cylinders array and deformed rhombic dielectric structure embedded in the middle layer and investigated the influence of energy flow for defect area by using the propagation constants at the guided area. From the numerical results, it is shown that we can obtain the confinement efficiency by rhombic dielectric structure compared with the deformed rhombic dielectric structure for both TE and TM modes.

In this letter, a novel ultra-wideband circular quasi-fractal monopole antenna with a six-petaled lotus pattern is presented. The CPW-fed technique and quasi-fractal concept are used to achieve ultra-wideband characteristics. The size of the proposed antenna is 4250 mm2 with a lotus diameter of 19.8 mm. The proposed antenna exhibits ultra-wideband characteristics from 2.65 to 12.72 GHz, which corresponds to a fractional bandwidth of 131%. The measured radiation pattern of the proposed antenna is nearly omnidirectional.

In the millimeter-wave band, the series-fed array antenna is facing a problem of large transmission loss and narrow bandwidth by using a high-permittivity and large-loss-tangent material. In this paper, an air region is inserted in the half of the height in the LTCC waveguide of εr =6.6 and tanδ =0.013 to reduce the transmission loss. The reduction of the equivalent dielectric constant by the air insertion structure enhances both the gain and the bandwidth of the series-fed slot array. The transmission loss of the single-mode rectangular waveguide has been reduced to about 1/6 by using the partially-filled structure in the 60-GHz band. In a one-dimensional slot array, the total loss has also been reduced to about 1/7. And the 3 dB-down gain bandwidth has also been increased from 1.3 GHz to 2.3 GHz.

Slotted-waveguide array antennas are attractive because of their low-loss characteristics at high frequencies. Several types of slotted arrays whose polarization angles are inclined to the waveguide axis have been reported. In this paper, we propose a new type of slot array antenna on a rectangular coaxial line for minimizing the waveguide width. As opposed to a conventional waveguide, there is no “cut-off” concept in our proposal because the coaxial line is a transverse electromagnetic (TEM) line. Therefore it is possible to guide the wave even if the diameter of the line is much smaller than that of the waveguide. Moreover, the proposed antenna is a resonant slot array antenna that is based on standing-wave excitation and is thus different from traveling-wave antennas (such as a leaky coaxial cable (LCX)).

A complete analysis of GaN-based structures with very promising characteristics for future optical waveguide devices, such as modulators, is presented. First the material growth was optimized for low dislocation density and surface roughness. Optical measurements demonstrate excellent waveguide properties in terms of index and temperature dependence while planar propagation losses are below 1 dB/cm. Bias was applied on both sides of the epitaxially grown films to evaluate the refractive index dependence on reverse voltage and a variation of 2.10-3 was found for 30 V. These results support the possibility of using structures of this type for the fabrication of modulator devices such as Mach-Zehnder interferometers.

Wavelength demultiplexed light switching is numerically calculated in the variable index arrayed waveguide. Wavelength demultiplexed light is switched in 4 output ports by changing the refractive index of variable index arrayed waveguide with 16 array waveguides. In the calculation, the phase differences in each arrayed waveguide, and the diffraction in the star coupler are considered. In 4 output ports switching, numerically calculated the refractive index changes of 16 array waveguides are numerically calculated to obtain the 24 switching pattern, and also calculated the crosstalk of each switching.