In this paper, a three-way divider is proposed for a partially-corporate feed in an alternating phase-fed single-layer slotted waveguide array. The divider is placed at the middle of the feed waveguide and reduces the long line effects; the frequency bandwidth is doubled. It is a kind of cross junction with one input port and three output ports; most of the power is equally divided into the right and left halves of the feed waveguide while the rest of power goes straight into the center radiating waveguide. Based upon the moment method design of the three-way divider, an inductive post is introduced for wide band power dividing control to the radiating waveguide. Reflection is below -20 dB over a wide bandwidth of 24.3-26.3 GHz, and the range of power dividing ratio ranges from 1/43 to 1/4. The amplitude and the phase from the two output ports to the feed waveguide are well balanced, and the differences are less than 0.1 dB and 5.0 degrees, respectively. The MoM analysis and the wide band design are verified experimentally in the 4 GHz band.

This paper presents designs and performances of 76 GHz band alternating-phase fed single-layer slotted waveguide arrays. Two kinds of design, that is, uniform aperture illumination for maximum gain and Taylor distribution for sidelobe suppression of -25 dB, are conducted. High gain and high efficiency performance of 34.8 dBi with 57% is achieved for the former, while satisfactory sidelobe suppression of -20 dB in the H-plane and -23 dB in the E-plane with high efficiency is confirmed for the latter. The simple structure dispensing with electrical contact between the slotted plate and the groove feed structure is the key advantage of alternating-phase fed arrays and the slotted plate is just tacked on the feed structure with screws at the periphery. High gain and high efficiency performances predicted theoretically as well as design flexibility of the alternating-phase fed array are demonstrated in the millimeter wave frequency.

We have presented a new analytical method for the stub-loaded ridge waveguide that is a candidate of leaky-wave antennas in the millimeter-wave region. This guide has many singular conductor edges, so that its accurate analysis is very difficult. The present method overcomes such difficulty by introducing the singular fields at the edges into the field expressions beforehand. Then we have investigated the dispersion characteristics for various structural parameters, to find a structure suitable to antenna applications. Finally, we have verified their behavioral feature experimentally.

In this paper, dosimetry of an in vitro exposure apparatus based on a cylindrical waveguide is performed. The SAR distributions are first obtained numerically by using FDTD method. The thermal fields in the medium are then estimated by numerical calculations of the equation of heat conduction. The maximum temperature rise for 17.9 W/kg average SAR during 3000 s exposure is about 2 on the bottom of the medium where cells are located. The thermal distribution is relatively uniform near the center of the dish and the temperature in this region is around 38.7. The results of the numerical calculation are experimentally supported. The results provide the electromagnetic and thermal characteristics of the exposure apparatus, which will define the exposure conditions of the planned experiments using this apparatus.

This paper presents a hybrid technique combining the mode-matching method and moment method to analyze various slots cut in the wall of a rectangular waveguide partially filled with a dielectric slab. The waveguide slot structure is decomposed into two parts: a dielectric-loaded waveguide T-junction and an open-ended waveguide radiating into half space. The T-junction is analyzed by the mode-matching method, while the open-ended waveguide is characterized by the moment method with the modal functions in the slot being the full domain basis functions. A new approach for computing multidimensional integrals is proposed in the formulation of the open-ended waveguide, which greatly reduces the computation effort. The T-junction and the open-ended waveguide are then cascaded to obtain the final scattering parameters of the slot structure. Numerical results for different slots on a dielectric-loaded rectangular waveguide calculated by the hybrid method are presented and validated by comparing with measured and simulated data by Ansoft's HFSS. Good agreement is observed for all the cases considered. Parametrical studies are also conducted to examine the effect of the dielectric slab's thickness and relative permittivity on slot antenna's impedance/admittance.

This paper proposes an efficient two-phase optimization approach for a compact W-band double-plane stepped rectangular waveguide filter design, which combines genetic algorithms (GAs) with the simplified transmission-line model and full-wave analysis. Being more efficient and robust than the gradient-based method, the approach can lead to a compact waveguide filter design. Numerical results show that the resultant waveguide filter design with 4 sections (total length 19.6 mm) is sufficient to meet the design goal and provides comparable performance to that with 8 sections (total length 35.6 mm) by the Chebyshev synthesis approach. Based on the present approach, nineteen compact high-pass waveguide filters have been implemented and measured at the W-band with satisfactory performance.

The increasing number of channels in dense wavelength division multiplexing (DWDM) systems has led to the need for wiring involving a large number of optical fibers in the system racks. We have developed a novel scalable optical fiber wiring system designed to realize as many as 10,000-fiber shuffled interconnections without fiber congestion. We propose a scheme for constructing a large-scale shuffler capable of permuting interconnected fibers that employs plural optical fiber sheets, and for arranging optical fibers without congestion in racks. We constructed a 16,384-fiber shuffler system with sixty-four 256-fiber shuffler sheets and 16-fiber fiber physical contact (FPC) connectors for a 128128 switch system with 1128 planar lightwave circuit (PLC) type thermo-optic switches (TOSW). Input here the part of summary.

A magnetic field probe consisting of a LiNbO3 optical waveguide modulator and a loop antenna element was developed to enable accurate measurement of magnetic near-fields in the gigahertz range. The invasiveness of the probe was assessed by using it to measure the magnetic field distribution above a patch antenna operating at 2.49 GHz. The measurements were compared with those obtained using a shielded loop probe. The experimental results obtained using the probe were also compared with simulation results obtained using a finite-difference time-domain (FDTD) method. The overall results indicated that the optical waveguide probe was capable of accurately measuring magnetic near-fields with low disturbance of the measured fields.

We propose and demonstrate a novel ladder interferometric filter that exhibits flat-topped spectral response for use in wavelength-division-multiplexing (WDM) based photonic networks. We numerically analyze the flattened spectral response in a ladder-type filter by modifying the transfer matrix of ladder interferometer. Conventional parabolic-shaped and flat-topped-designed ladder interferometric filters are fabricated, and characterized. We demonstrate a flat-topped filter response in the fabricated device. The shape factor, which is defined by the ratio of -1 dB bandwidth to -10 dB bandwidth, is improved from 0.32 to 0.54. The tunability and the increase in filter extinction ratio of the proposed device are also discussed.

A technique to control the radiation pattern of an NRD-guide-compatible pyramidal horn antenna, which consists of a tapered dielectric rod inserted into the horn, was developed for multiple access LAN applications at 60 GHz. By using this simple technique, the half-power beamwidth can be controlled from 11to 40.

The authors realize a 50% length reduction of short-slot couplers in a post-wall dielectric substrate by two techniques. One is to introduce hollow rectangular holes near the side walls of the coupled region. The difference of phase constant between the TE10 and TE20 propagating modes increases and the required length to realize a desired dividing ratio is reduced. Another is to remove two reflection-suppressing posts in the coupled region. The length of the coupled region is determined to cancel the reflections at both ends of the coupled region. The total length of a 4-way Butler matrix can be reduced to 48% in comparison with the conventional one and the couplers still maintain good dividing characteristics; the dividing ratio of the hybrid is less than 0.1 dB and the isolations of the couplers are more than 20 dB.

We present a low-phase-noise and frequency-tunable photonic millimeter-wave (MMW) generator based on two-mode beating. The generator consists of a single-mode laser, an external optical intensity modulator, and a planar lightwave circuit (PLC) on which an arrayed-waveguide grating (AWG) and 3-dB optical combiners are integrated. Because the AWG and the optical combiners are connected with optical waveguides and the optical path length difference between the two modes filtered by the AWG is kept constant, the phase fluctuation of the generated MMW signal is suppressed. The generator can generate MMWs with a phase noise of less than -75 dBc/Hz at 100 Hz and has a frequency tunability in a range of 90 to 125 GHz. The generator can be applied for the local oscillator (LO) in 10-Gbit/s wireless links that use heterodyne detection.

Two types of miniaturized high-temperature superconducting filters are described in this paper. The first type is developed by using small-sized microstrip spiral resonators, and the second type by coplanar waveguide quarter-wavelength resonators. The filters have significantly reduced size compared with many previous HTS filters. They are designed by employing an electromagnetic simulator in combination with appropriately chosen equivalent circuits. Their measured frequency responses agree well with theoretical predictions, and show low insertion losses in spite of their small sizes.

In order to reduce the size of a wireless system, we propose a design theory for the broadband impedance matching circuit which connects an electrically small antenna (ESA) to a semiconductor amplifier. We confirmed its validity for the case of connection between a small slot loop antenna with a small radiation resistance of Ra =0.776 Ω and a semiconductor amplifier with high input impedance of ZL =321-j871 Ω with the aid of the simulations by the electrical circuits using transmission lines as well as the electromagnetic field (EM field) simulator. We also made experiments on this antenna with matching circuits using high temperature superconductor YBCO thin films on MgO substrates.

The reflection characteristics of large alternating-phase fed single-layer waveguide arrays with center-feeds are investigated to identify the mechanism for bandwidth narrowing effects. Firstly, the overall reflection for the whole array is analyzed by FEM and fine agreement with measurements is demonstrated. It is deviating from the conventional prediction based upon a simple sum of reflections from components in the array, such as the multiple-way power divider, the slot waveguides and the aperture at the antenna input. Careful diagnosis reveals that the mutual coupling between the alternating phase waveguides via external half-space is the key factor in reflection accumulation. Amongst all, the slot with strong excitation whose position depends upon the aperture illumination design produces the dominant contribution in the mutual coupling.

We propose an information-sharing network system, capable of forming and dynamically reconfiguring multiple information-sharing groups on the same network platform by using wavelength routing and distributed shared memory technologies. The network system comprises information-sharing terminal nodes equipped with a shared memory and a wavelength-tunable transmitter, network management terminal and an arrayed-waveguide grating (AWG). The information-sharing terminal nodes are connected to an AWG by a pair of optical fibers, forming a star-shaped topology. Information is shared among the information-sharing terminal nodes through the establishment of a logical information-sharing ring. This is accomplished by adjusting the output of the wavelength-tunable transmitter at each terminal node to an appropriate wavelength according to the wavelength-routing characteristics of the AWG wavelength router. We developed a prototype information-sharing network system, in which, as preliminary experiments, HDTV and SDTV videos were used for real-time information sharing. The dynamic reconfiguration of information-sharing groups and a simple automatic restoration technique have been successfully demonstrated. The system is applicable to distributed computer processing systems and high-capacity information-sharing applications such as high-quality videoconferences.

A fully integrated broadband distributed frequency tripler, periodically loaded with HBV devices, has been designed and fabricated and has demonstrated the generation of a broad range of output frequencies of up to 570 GHz. Key to the design is the principle that the entire frequency tripler circuit is produced monolithically and incorporates novel HBV devices electrically and mechanically interconnected by a thin low-loss SU-8 membrane. With the device fabrication approach used, the novel HBV devices are able to produce a higher capacitance-voltage swing ratio whilst simultaneously minimizing the device series and contact resistances to achieve the optimum conversion efficiency. The entire concept of this work was to design a cost effective fully integrated waveguide package, with the frequency tripler circuit mounted at the E-plane of a micromachined waveguide which was constructed with stepped height and width to prevent the propagation of higher order modes inside the waveguide sections. The micromachined waveguide sections exhibit high dimensional accuracy and a good surface finish which is necessary for the efficient propagation of high frequency signals. The frequency tripler circuit and the accompanying micromachined waveguide sections are mounted in a specifically designed metal test fixture to form a compact and cost-effective subcomponent with great commercial potential for broadband harmonic generation of up to terahertz frequencies. This paper presents the design methodology and techniques used to produce the frequency tripler package, together with some initial measurement results.

The recent progress in the field of Ti:Er:LiNbO3 waveguide lasers with emission wavelengths in the range 1530 nm < λ < 1603 nm is reviewed. After a short discussion of the relevant fabrication methods concepts and properties of different types of lasers with grating resonator, acoustooptically tunable Fabry Perot type lasers and new ring laser structures are presented.

This paper describes improvement of the gain in the Er-doped lithium niobate waveguide optical amplifiers. A new configuration is proposed, which is loaded with a high-index cladding for the purpose of realizing a larger overlap between the guided light fields and doped Er ion-concentration. It is shown by theoretical simulations and also by experiments that the clad is advantageous to shifts of the light fields toward the substrate surface, and that the overlap between the light field and Er ion-concentration becomes large. Improved optical gains are measured for a fabricated device with a thin-TiO2 clad in the LiNbO3 substrate.

A GaInAs/InP multiple quantum well (MQW)-based wavelength demultiplexer composed of a waveguide array in which the refractive index varies across the array yielded successful results of wavelength demultiplexing and optical deflection. Since optical path length differences between waveguides in the array are achieved through refractive-index differences controlled by the SiO2 mask design in selective metal-organic vapor phase epitaxy (MOVPE), a straight waveguide grating can be formed with reduced optical propagation losses. A straight waveguide array device with a 1.4% refractive-index difference was fabricated. The fabrication of a preliminary wavelength demultiplexer was also achieved, for which a wavelength separation with an approximately 25 nm spacing and free spectral range (FSR) of approximately 100 nm were obtained. Moreover, an optical deflector was investigated and primitive deflection was achieved at 1460 and 1490 nm incident wavelengths.