bluuebunny/crossref_metadata_2025_split huggingface dataset:
Small‐sized waveguides with periodically loaded double posts
Authors: Kim Ki Chai , Tokumaru Shinobu 
Published: July 2007

AbstractThe authors have already proposed small‐sized waveguides with periodically loaded posts along a single line placed inside the cut‐off rectangular waveguides. This paper proposes small‐sized waveguides with periodically loaded double posts which have two lines of posts inside the waveguides aiming at an increase of the transmitted power there. The phase constants, the field distribution and other characteristics were obtained theoretically. They were evaluated numerically and these numerical results were confirmed by experimental measurements. This paper considers the transmitted power. Using the same size of the waveguide with a single line of posts, the maximum transmitted power increased by a factor of 1.7 and the transmission losses were reduced by about 6.38 percent by using double posts for the same numerical results of the waveguide with a single line of posts. As in the case of the waveguide with a single line of posts, either slow waves or fast waves can be transmitted. The transmission characteristics can be controlled easier by the values of the reactive loads by the double post structure.
Design of a radial line slot antenna with improved input VSWR
Authors: Ando Makoto , Ito Shuji , Kawasaki Hideji , Goto Naohisa 
Published: July 2007

AbstractA radial line slot antenna is a planar antenna which in principle has high efficiency. An excellent efficiency of no less than 57 percent has been measured in the 12‐GHz band. To realize the predicted 80 percent efficiency, reflection in the antenna feeding structure should be suppressed. In this paper, field analysis by means of the finite element method (FEM) provides the shapes of the feeding structures which minimize the reflection. Numerical results predict that the antenna overall reflection can be suppressed to less than ‐15 dB. The theoretical design is confirmed by the model experiments in 6‐GHz band. The optimum design reduces the efficiency degradation due to reflection from 15 to 3 percent.
Synthesis of a two‐dimensional linear feedback shift‐register capable of generating a given two‐dimensional array
Authors: Sakata Shojiro 
Published: July 2007

AbstractThis paper considers a synthesis problem for the 2‐D linear feedback shift‐register with the minimum number of storage devices capable of generating a given finite 2‐D array. An efficient algorithm for finding a set of polynomials which characterizes a minimal 2‐D pseudolinear feedback shiftregister is proposed. Berlekamp‐Massey's algorithm which determines a 1‐D linear feedback shift‐register with the minimum number of storage devices capable of generating a finite 1‐D array is extended to the 2‐D case. If the given array is a subarray of a doubly periodic array with a sufficiently large size, i.e. at least twice as large compared with the fundamental period parallelogram, the obtained set of polynomials is unique, and it determines the unique 2‐D linear feedback shift‐register as its physical realization.
Synthesis of Balanced Stripline Branch‐Line 3‐DB Hybrid Circuit Based on Planar Circuit Model
Authors: Anada Tetsuo , Jui‐pang Hsu 
Published: July 2007

AbstractWhen a transmission‐line type branch‐line 3‐dB hybrid is realized with a strip‐line circuit at high frequencies, electromagnetic disturbances occur near the transmission‐line junctions. Also, due to their mutual interference, the frequency characteristics are degraded from the desired ones. To treat this electromagnetic disturbance effectively, the transmission‐line type branch‐line 3‐dB hybrid circuit is separated into the branching transmission lines and the junction circuit. Based on the analysis for the function of each portion, the equivalent circuits are derived. It is described how these equivalent circuits are realized with stripline circuits with planar breadth. In practice, the balanced striplines are approximated by planar transmission line models so that the entire hybrid circuits are replaced with the planar transmission line circuits. The planar circuit theory is then applied to these structures so that the deviation from the desired hybrid characteristics due to the electromagnetic disturbance at the transmission‐line junctions is incorporated in the synthesis. Further, a hybrid circuit is designed with balanced striplines and the corresponding circuit is fabricated and tested. The measured results agree well with the theoretical frequency characteristics. Hence, the validity and effectiveness of the method are confirmed.
Gateway buffer size of local area network
Authors: Matsumoto Yutaka , Takine Tetsuya , Takahashi Yutaka , Hasegawa Toshiharu 
Published: July 2007

AbstractWhen different kinds of local area networks are interconnected, a gateway holds the key to better performance of the interconnected network. Since gateways are lia‐able to overflow easily because of their comparatively long processing time, it is necessary to estimate their appropriate buffer size with regard to the input traffic. This paper considers a local area network working under CSMA/CD protocol. First, we analyze the output process of messages which constitutes a part of arrival process at a gateway, by solving an embedded Markov chain. Second, two stochastic models of the gateway are formulated by queueing theory and loss probability of messages is evaluated in regard to its buffer size. Numerical results show some interesting features of the output and arrival processes.
Fully digital cross polarization interference canceller for multilevel digital radio
Authors: Matsue Hideaki , Ohtsuka Hiroyuki , Murase Takehiro 
Published: July 2007

AbstractIn the digital radio system using dual polarizations, an interference canceller is needed that cancels excessive interference. In this paper, a fully digital cross‐polarization interference canceller is proposed in which digital signal processing (DSP) technology and LSI technology are applied. By means of DSP technology, the cancellation characteristics are determined mainly by the quantization accuracy and the number of taps. The only degradation factor is the rounding‐off error of the operations. High accuracy and large cancellation effects are expected. Also, an application of an advanced control algorithm is possible. Flexible applications are possible for any symbol rate. In this paper, the estimation method for the fully digital cross‐polarization interference canceller is presented. Based on this method, the relationships among the cancellation characteristics, the input signal quantization accuracy, tap coefficient quantization accuracy, and number of taps are analyzed theoretically for the case where the method is applied to the 256 QAM system. Next, the configuration of the canceller is presented. From the results of the experiments using the symbol rate of 12.5 MBaud and 256 QAM signals, good agreement with the theoretical prediction is obtained and, hence, the validity of the present estimation method is demonstrated. It is demonstrated that a high‐performance cross‐polarization interference canceller is realized which can be applied to a multilevel modulation system for a high‐speed region, such as 12.5 MBaud.
A cutoff cavity antenna with resonant posts
Authors: Kim Ki Chai , Tokumaru Shinobu 
Published: July 2007

AbstractA cutoff cavity antenna is proposed in which excitation and parasitic posts are placed inside the antenna cavity. The input impedance of the antenna can be varied freely and matched. Its fundamental characteristics are obtained theoretically. The values of the load reactances which were connected externally to those posts are controlled and can be matched for a desired operating frequency. The current distribution on the excitation and parasitic posts and the electric field distribution over the aperture were analyzed. Integral equations for those distributions were derived and solved by Galerkin's moment method. In addition, the determinantal equation to obtain matched load reactances was obtained. Numerical examples were presented for the current distribution and the aperture electric field under a matched condition. Experiments were conducted on a test antenna and the validity of the theory was discussed.
Stability analysis of combined random/reservation access methods
Authors: Onozato Yoshikuni , Kato Tatsuhito , Noguchi Shoichi 
Published: July 2007

AbstractThe combined random/reservation access method is one of the access schemes in satellite packet communication networks which exhibits a desirable performance in adapting to the load variation. In the analysis of the system performance up to the present, however, the stability of the system has not been discussed fully. This paper considers the AA/TDMA (adaptive assignment/time division multiple access) scheme as an example of the random combined reservation access. The system is modeled using the equilibrium analysis, and the stability of the AA/TDMA system is discussed in detail using the theory of catastrophe. The change of the stability according to the load variation is described qualitatively using the wedge catastrophe. Furthermore, the stability condition is described qualitatively.
Effect of error control system by range transmission for PCM sound broadcasting
Authors: Kawai Naoki , Yoshino Takehiko 
Published: July 2007

AbstractIn the PCM sound broadcast by digital transmission, the noise due to the bit‐error at low reception field intensity degrades the speech quality, which restricts the range of broadcast reception. A method to reduce the bit‐error noise is the error control by range transmission, where the information indicating the range of the significant bit in the sample in a specified interval is transmitted as the range data. This paper presents a quantitative analysis for the reduction of the bit‐error noise, for the traditional range transmission system and the control system by majority decision, to fully utilize the merit of the method. The improvement from the viewpoint of listening sensation was verified by a subjective evaluation test. It is shown that the proposed method exhibits a remarkable improvement in the low‐intensity reception with a high error‐rate, where the error‐correcting code cannot achieve a sufficient improvement. It is shown by experiment that seven levels of the transmission range are sufficient to achieve the desired performance.
Three‐dimensional electromagnetic analysis by the subspace synthesis method
Authors: Nagaike Masaru , Ichiyanagi Takashi 
Published: July 2007

AbstractThe required computer memory capacity and the calculation time become enormous when analyzing problems for three‐dimensional electromagnetic fields by finite‐element methods. In many cases calculation is difficult even by a super‐computer. To save the required computer memory capacity and computer time, we propose a subspace synthesis method, an outline of which is as follows. First, the object space is divided into several subspaces. In each subspace we apply the finite‐element method. We formulate dispersed equations for each subspace. From these equations we derive reduced equations which relate only the unknown coefficients on connecting regions among sub‐spaces. By combining reduced equations from all subspaces, we obtain the reduced equations for the total object space. By solving them we can obtain the electromagnetic fields. In the proposed method, we execute calculations for a small subspace one at a time. Therefore the required computer memory capacity is reduced greatly from that for analyzing the object space by the direct application of the finite‐element method. The corresponding computer calculation time is also reduced. This paper shows the formulation of the subspace synthesis method, and applies it to several examples. The calculation results by the present method were compared with rigorous solutions or experimental data. The effectiveness of the proposed method was shown from these comparisons.
Optical‐loss change characteristics of fiber organizers for optical‐fiber cable joints
Authors: Shimizu Masatoshi , Kobayashi Hideo , Tomita Nobuo 
Published: July 2007

AbstractThis paper discusses and evaluates optical‐loss change characteristics which occur in the process of installing the optical‐fiber splicing points and slack fibers into an optical‐fiber organizer. First, as the optical‐loss change factors, bend lateral force and twisting were discussed. Their effects on the loss characteristics have been studied theoretically and experimentally so that the main factor for degrading the transmission characteristics is the bending process of the slack fiber. Next, the evaluation method for the optical‐loss change characteristics is studied at the fiber joint for the analog baseband video signal transmission. It is found that the allowable optical output vs. optical‐loss change ratio SNRC is 37.1 dB, and the bend radius is satisfying the present allowable SNRC at all frequency components of the optical loss change is more than 18 mm. Also, the relationship was studied between the bending radius of the fiber satisfying this SNRC and the changing frequency. It is found that the allowable bend radius can be relaxed by about 20 percent by doubling the fiber organizing time. Further, the optical‐loss change characteristics have been evaluated for the individual organization and the simultaneous organization. It is pointed out that the individual organization is suited for subscriber optical cables.
Flame‐Resistant Optical Fiber Cable with Corrosion‐Protective Painted Stainless Steel Sheath
Authors: Kuwabara Tsuneo , Koga Hiroaki 
Published: July 2007

AbstractA flame‐resistant optical fiber with a stainless steel sheath is proposed. As a result of the flame test (IEEE 383 Standard) on a 12‐fiber optical fiber cable based on the proposal, it was found that only the corrosion‐protective paint on the stainless steel surface, which was exposed to the flame, was burned (burn length 30 to 45 cm). During this IEEE 383 Standard Flame Test, the fiber did not show any increase of optical loss. However, the optical loss began to increase within a certain period of time after the flame test, and the period is longer when the softening temperature of the secondary coating material is lower. The stainless steel surface should be coated with corrosion‐resistance paint. As a result of the corrosion test, the chromate treatment is suitable for surface treatment. Vinyliden fluoride paint, dicarbolic acid paint with glycidyl acrylic or oil‐free melamine polyester paint are effective for corrosion protection.
Experimental study on shielding effect for shielding cable in metallic duct
Authors: Yamane Hiroshi , Kanamori Hisaaki , Ideguchi Tsuyoshi , Motomitsu Tamio 
Published: July 2007

AbstractWhen transmission lines are short circuited to the ground by accidents, induced voltages are induced between the conductor wires and the ground at the ends of communication cables. To reduce the induced voltages below the restricted voltage (430 V rms), we used countermeasures employing shielding cables and arrestors. However, studies for installation methods of shielding cables in metallic ducts have been insufficient. Many points of the shielding effect have not been clarified. In this paper we consider the shielding effect of the shielding cables installed inside metallic ducts buried in the ground which have distributed grounding resistances. We proposed a new laboratory measurement method for clarification by using small‐scale models including the current distribution in the metallic ducts. We examined experimentally through this new method, shielding characteristics of shielding cables in metallic ducts. As a result, we clarified that the shielding factor has a minimum value for the induced longitudinal voltage, the shielding effect becomes prominent if the distribution of the grounding resistance of the metallic duct is below 103 ω m, and the shielding effect is in proportion to the cable length. Compared with a case of a shielding cable only, we found that the shielding cables in metallic ducts have larger shielding effects. We clarified that they are effective for shielding in areas with induced fields of high intensities.
Bit error rate analysis for frequency deviation companding and expanding FM (fredece FM)
Authors: Ohno Koji , Daikoku Kazuhiro , Ogose Shigeaki 
Published: July 2007

AbstractIn this paper, bit error rates (BERs) of Fredece FM are analyzed theoretically. The correlative code whose transmission bandwidth is preliminary limited by Nyquist filter, is used for obtaining the Fredece FM signal. The spectrum of the Fredece FM signal is compact enough to adopt for mobile radios. However, the correlative code generally requires a multilevel decision. In the demodulation process, the received signal is frequency‐multiplied prior to the differential detection. This makes it possible to perform the binary decision. It is noted that the BER performance of Fredece FM is the same as that of the case where a multilevel differential detection is performed without frequency multiplication. Therefore the frequency multiplication is regarded as linear amplification in the frequency region. It is easy to analyze theoretically BERs with the multilevel differential detection for Rayleigh fading. Then the BERs for nonfading are derived easily by using the property where the average BER for quasi‐static Rayleigh fading is related to that for nonfading through Laplace transform. Finally, the relationship between the modulation index and the irreducible error level is studied.
Experiments of diffraction error on MLS elevation guidance
Authors: Koremura Kazunobu 
Published: July 2007

AbstractIn the diffraction region of a microwave landing system (MLS) elevation guidance, the field strength fluctuates due to such objects as buildings and hence the measuring error increases. This paper describes experiments to determine the effect of diffraction caused by the upper edges of a building. The results show that the field has a typical diffraction characteristic which can be calculated by regarding the building as a knife edge. It was found that the diffraction error cannot be ignored when measuring an angle, since the scanning beam is sharp in the vertical direction and flat in the horizontal direction. Hence, both the component proportional to the amplitude of the diffraction wave and that proportional to the partial differentiation of its incident angle (slope diffraction component) increase. It was found also that the measurement error characteristic around the shadow boundary, calculated by using the uniform geometrical theory of diffraction taking account of the slope diffraction, agrees well with the observational results. Generally, this method can be applied to the diffraction field strength and its measuring error estimation such as hangers.
Exact radio link design in cellular mobile communication systems
Authors: Kanai Toshihito 
Published: July 2007

AbstractIn the design of a radio link for terrestrial mobile communication, the transmitter power and the cluster size are determined based on the specification derived from the quality requirement and the outage. In the traditional design, the required quality and the outage are allocated according to the two degrading factors, i.e., the noise and the co‐channel interference, and the transmitter power and the cluster size are determined independently. The method is employed widely because of its simplicity, even though there is a certain error in the designed values. By contrast, this paper proposes an exact design for the radio link, where the reliability of the designed value is emphasized, aiming at a more efficient utilization of the frequencies. The concept of the prescribed quality transmission curve which considers simultaneously the two degrading factors, is newly introduced. The expression for the outage is derived from the prescribed transmission quality curve and the joint probability of the carrier‐to‐noise power ratio (CNR) and the carrier‐to‐interference power ratio (CIR). The relations among the outage, transmitter power and the cluster size are determined. As a precise method of calculation, a method is presented which gives the graphical relation between the transmitter power and the outage, with the cluster size as the parameter. Using a design example, it is shown that the minimum cluster size, which has been 12 in the traditional method, is now 9 by the proposed method. Thus, the usefulness of the method in the frequency utilization is indicated.
A study on layered free access network
Authors: Shikata Yoshiaki , Funakawa Kimitoshi 
Published: July 2007

AbstractA layered free access network is proposed. This network is composed of multichannel circuits of bus type, such as LAN, satellite channel, etc., and traffic nodes which access multichannel circuits. By combining the nodes which can access all circuits and the circuits used only by a part of the nodes, a layered network structure can be constructed in accordance with the internode traffic distribution pattern. The number of access equipment in a node is evaluated and the existence of the optimum network configuration for an internode traffic distribution pattern is shown. An algorithm for obtaining the optimum network configuration is presented and an example of the optimum network configuration based on the traffic model is shown.
Optical fiber cable flexibility design under plastic deformation and its evaluation
Authors: Hayashi Akira , Mitsunaga Yutaka , Koga Hiroaki 
Published: July 2007

AbstractThis paper discusses the flexibility of a cable when it is bent to the range of plastic deformation of the cable material. Considering the situation where the cable material exhibits elastic or plastic deformation, the expression for the maximum bending moment, which represents the flexibility of the cable, is derived in terms of the following parameters: The strain‐hardening exponent n and the plastic modulus which are material parameters; and the outside and the inside radii r1 and r2, respectively, which are the structural parameters. As a method to determine the foregoing material parameters experimentally, the three‐point bending test is discussed. A method is presented which determines the strain‐hardening exponent n and the plastic modulus from the relation between the load P and flexion δ. The method is verified experimentally. The case is considered where the cable is composed of several materials such as sheath, core, and tension member, and it is demonstrated that the bending moment of the whole cable is given as a sum of the bending moments of the component materials. Thus, it is shown that if the material parameters of the cable components are known, the maximum bending moment of the whole cable, representing the flexibility, can easily be designed.
A direction‐finding algorithm of reflected waves using small‐sized data series measured in fresnel region and its evaluation
Authors: Wang Jianqing , Echigo Hiroshi , Takagi Tasuku , Sato Tsugio 
Published: July 2007

AbstractTo find the unwanted reflection characteristics of a Fresnel region wave from a building and a wall, it is necessary to know the direction of the reflection source. This paper proposes an algorithm which estimates successively the direction of arrival of the reflected wave in the Fresnel region, based on the study of the characteristics and the shape of the spatial series in that region. This algorithm is realized by a combination of the maximum entropy method in which a spectrum can be estimated at a high resolution with a few data and an error correction by the Newton‐Raphson method for solution of a nonlinear equation. To confirm the validity, a computer simulation and experimental results are shown. In the computer simulation results, the reflection direction was estimated with an error of 0.1° ‐ 2.9° from 40 measured data for an aperture of 5 wavelengths. In the experiment, the reflection direction was estimated with an error of less than 0.5°. From these results, it is found that this algorithm can be applied for direction finding of the reflected wave under an actual electromagnetic environment.