We report the investigation of major dispersion mechanisms such as self-heating, trapping, current collapse, and floating-body effects present in AlGaN/GaN HFETs. These effects are analyzed using DC/Pulsed IV, load-pull, low-frequency noise systems, and a cryogenic probe station. This study leads to a better understanding of the device physics, which is critical for accurate large-signal modeling and device optimization.

We report in this paper, the performance of AlGaN/GaN HFETs in the context of high power, low noise and high temperature operations, along with a comparison of their characteristics with other conventional technologies. Finally, a single stage modulator driver for long haul optical communications is presented as an example of application of the GaN-based devices high power handling capabilities.

The first implementations of X-band AlGaN/GaN HEMT single-ended frequency doublers are presented in this paper. Two types of fundamental frequency signal reflector schemes have been demonstrated for the frequency doubler application. Open-circuited quarter-wavelength microstrip line at the fundamental frequency is utilized for the reflector in a conventional way. In the other architecture a printed antenna is employed as a radiator as well as a novel fundamental frequency reflector. A microstrip rectangular patch antenna operating at the second harmonic frequency of the doubler was designed and integrated with AlGaN/GaN HEMT based on active integrated antenna design concept. Using AlGaN/GaN HEMT with 1 mm gate periphery, two 4 to 8 GHz frequency doublers were designed by the described design methodologies, fabricated, and tested. For the conventional frequency doubler, a conversion gain of 0.6 dB and with an output power of 15 dBm was observed. A conversion gain of 5 dB and an output power of 25 dBm with embedded antenna gain were achieved at a drain voltage of 12 V for the doubler integrated with the patch antenna.

An ultra-low power 4.3 GHz Synchronous Oscillator (SO) is presented, integrated in a 0.25 µm BiCMOS SiGe technology, to act as the RF loop of an UMTS double-loop synthesizer. This SO is tunable in order to counteract technology discrepancies. Hence, the synchronization range is smaller, reducing unwanted synchronization and improving the frequency generation accuracy. This 1.8 V SO provides a -115 dBc/Hz phase noise at 100 kHz offset, consuming only 3.6 mW.

The fully integrated LC voltage controlled oscillator by 0.35 µm CMOS technology is demonstrated. It has 2 GHz oscillation frequency, 23.58 mW power consumption under 3 V biased and 9.1% frequency tuning. The layout optimization method of inductor to increase quality factor and also to reduce phase noise is used. A general method is proposed which is capable of making an effective prediction of F, device excess noise number, and acquiring the phase noise of oscillators accurately. From this proposed method, the low phase noise by calculation is attained. The phase noise of measured value which shows good match with calculating data is about -115.5 dBc/Hz at off set frequency 600 kHz.

A novel push-push oscillator taking advantages of "Double-Sided MIC Technology" is proposed. The oscillator incorporates microstrip lines on a dielectric substrate and a slot line on the reverse side. By integrating a slot line and microstrip lines, the push-push oscillator can be realized very easily. All the concerned undesired harmonic signals (f₀, 3f₀ and 4f₀) can be suppressed satisfactorily. Using these approaches, a push-push oscillator in K-band is designed and fabricated. The output power of +4.17 dBm at the frequency of 21.25 GHz is measured. All the undesired signals are sufficiently suppressed to be better than -30 dBc. The phase noise is -99.68 dBc/Hz at the offset frequency of 1 MHz.

In this paper, a novel circuit structure of Push-Push oscillator using λg/2 microstrip resonator is proposed, in which a common resonator plays two functions of frequency determining and power combining. This type of Push-Push oscillator is named "Dipole Resonator Push-Push oscillator" here, where an additional power combiner circuit required in conventional Push-Push oscillators can be eliminated. The Push-Push oscillator adopting this design concept has the advantages of the easy circuit design, the simple circuit structure and the miniaturization of the circuit size. As a most simple example of this design concept, a K-band Push-Push oscillator using a λg/2 microstrip resonator is designed and achieved. The high output power of +8.4 dBm at the frequency of 21.68 GHz (2f₀) is obtained with the phase noise of -100.5 dBc/Hz at the offset frequency of 1 MHz. Besides, a high suppression of the undesired fundamental frequency signal (f₀) of -26 dBc is realized.

A constant voltage/constant current (CV/CC) parallel operation heterojunction bipolar transistor (HBT) power amplifier (PA) configuration is presented, and its design method is described. A resistor base feed (CC mode) HBT is connected to an inductor base feed (CV mode) HBT in parallel, and compensates the gain expansion of the CV mode HBT due to near class-B operation. By adding CC mode HBT, the total quiescent current can be decreased from 32 mA to 23 mA with adjacent channel leakage power ratio (ACPR) < -40.0 dBc. At the maximum output power region, the fabricated PA achieves output power (P_out) of 26.8 dBm and power added efficiency (PAE) of 42.0% with ACPR of -40.0 dBc, and shows the comparable performances with a conventional PA using CV mode HBT.

A microwave waveform measurement system below 18 GHz was developed and verified with a conventional RF measurement. The current and voltage RF waveforms of AlGaAs HBTs at the fundamental frequency of 1 GHz were directly measured with the system. A new direct method of sweeping and measuring dynamic RF load lines is proposed to measure the operating limits of the device. The maximum operating region was experimentally investigated with this method. The limits with a small input power are found to come from thermal runaway and the avalanche breakdown of the device. With a large input power, the HBT was found to operate beyond the DC limit of thermal runaway. The base ballasting resistance was also found to enhance large signal operating limits beyond those expected from the conventional DC theory.

A 270 GHz-band image rejection SIS mixer is developed. This mixer employs planer type image rejection configuration and is integrated into a single-chip as in MMIC's at microwave frequency. In order to use sapphire substrate at 270 GHz-band, CPW transmission lines are selected to realize 50-70Ω characteristic impedances. The fabricated MMIC SIS mixer performs 12-24 dB image rejection ratio with 450-780 K noise temperature at 270 GHz.

This paper presents an even harmonic mixer using self-biased anti-parallel diode pair (APDP). A proposed self-biased APDP is composed of a pair of diodes and self-bias series resistors. At high LO injection level, rectified current is generated by the diodes and reverse voltage is applied to the diodes by the self-bias resistor. Therefore, rapid degradation of conversion loss at high LO input level can be avoided. The effect of self-bias resistor is explained by using simplified behavior model and harmonic balance method, and is evaluated by the measurements of an L-band even harmonic type direct conversion mixer.

We present a physics-based circuit simulator employing the Monte Carlo (MC) particle technique, which serves as a bridge between the small-device physics and the circuit designs. Two different geometries of GaAs-MESFET's are modeled and analyzed by the simulator. The Y-parameters of the devices are extracted from the transient currents, and then translated into the S-parameters. The cut-off frequency (f_T) is estimated from the Y-parameters. The minimum noise figure (F_min) is also estimated by evaluating the fluctuation in the stationary current. The device, having the n⁺-region placed just at the drain side of the gate, exhibits the better performances in both f_T and F_min. The analysis on the equivalent circuit (EC) elements reveals that its better performances are mainly due to the reduced gate-source capacitance (C_gs) and the increased transconductance (g_m0), which result from the shortened effective gate length (L_g) caused by the termination of the depletion region at the gate edge. The termination of the depletion region, however, causes the increase of the electric field, which results in the higher heat generation rate near the gate edge. It is proven that the physics-based circuit simulator developed here is fully effective to see the inside of the small-device and to model it for the millimeter-wave circuit design.

An analysis method based on the FD-TD and radiation mode expansion methods and its simulation tool are developed for calculating circuit characteristics and parameter values of passive MMIC (Monolithic Microwave Integrated Circuits) elements having multilayer structure. For straight multilayer microstrip lines and coplanar waveguides, it is possible to calculate characteristic impedance, effective permittivity, transverse field distribution of guided modes, etc. For various multilayer microstrip and coplanar waveguide elements, it is possible to calculate scattering parameters, radiated power, radiation patterns, etc. As an example of application of the present technique, effects of inclusion of lower permittivity layer in the substrate on transmission and radiation characteristics are investigated for right-angled microstrip bends.

An 18 GHz-band Microwave Monolithic Integrated Circuit (MMIC) diode linearizer using a parallel capacitor with a bias feed resistance is presented. The newly employed parallel capacitor is able to control gain and phase deviations of the linearizer. This implies that the gain deviation of the linearizer can be controlled without changing the phase deviation. The presented linearizer can compensate the distortion of an amplifier sufficiently. The operation principle of the linearizer with the parallel capacitor is investigated. It is clarified that the gain deviation can be adjusted without changing the phase deviation by using the parallel capacitor. Two variable gain buffer amplifiers and the core part of the linearizer which consists of a diode, a bias feed resistor, and a capacitor are fabricated on the MMIC chip. The amplifiers cancel the frequency dependence of the core part of the linearizer to improve bandwidth of the MMIC. Further, the amplifiers contribute to earn low reflection and compensate insertion loss of the linearizer. The MMIC chip is size of 2.5 mm 1 mm. The linearizer has demonstrated improvement of 3rd Inter-Modulation Distortion (IMD3) of 12 dB at 18 GHz and improvement of more than 6 dB between 17.8 GHz and 18.6 GHz.

Weight divided adaptive control method for a microwave FeedForward Power Amplifier (FFPA) is presented. In this adaptive controller, an output signal of a power amplifier is used as reference signal. Additionally, reference signal is divided by the weight of adaptive filter, so that characteristics of the power amplifier, such as temperature dependence, do not have influence on the convergence performances. The proposed adaptive algorithm and the convergence condition are derived analytically and we clarify that the proposed weight divided adaptive algorithm is more stable than the conventional Normalized Least Mean Square (NLMS) algorithm. Then, the convergence condition considering phase calibration error is discussed. The effectiveness of the proposed algorithm are also verified by the nonlinear simulations of the FFPA having AM-AM and AM-PM nonlinearity of GaAsFET.

10-Gbit/s wireless data transmission using 120-GHz millimeter-wave (MMW) photonic technologies is presented. For such high-data-rate transmission, we have newly developed a planar broadband receiver that employs a > 200-GHz Schottky diode and a slot-ring antenna with a 10-dB bandwidth of 30 GHz. The receiver achieves a high video sensitivity of 190 mV/mW at 120 GHz due to its optimized data output circuit. The MMW wireless link using the receiver and photonic transmitter has data transmission bandwidth of 8.5 GHz, and succeeded in 10-Gbit/s data transmission, which is the fastest ever achieved through a MMW wireless link.

This paper presents an advanced quad-band multi-chip power amplifier module with unique linear output power dependency to the control voltage. It was developed for GSM850/900 MHz and DCS1800/PCS1900 MHz handset applications. The module was made on 10 mm by 10 mm substrate, which combined an InGaP HBT GSM, and DCS power amplifier ICs, two integrated couplers, a dual-band logarithmic RF power detector and some additional passive components. The logarithmic RF power detector was implemented in the module using state-of-the-art Si technology to accomplish the linear power dependency. With the logarithmic RF power detector approach we achieved more than 50 dB linear output power control range. The output power in dBm is a linear function of a control voltage; therefore there is no need for the Original Equipment Manufacture to design a power control circuitry. This is a very desirable feature to many handset designers who want to significantly reduce the handset board size, design cost, and time-to-market. The approach allows the handset manufacturer to calibrate the output power at two points with error of less than 0.3 dB, thus significantly reducing test time in mass production. Under a low single supply voltage of 3.2 V the module provides 35 dBm output power, 55% PAE in GSM900 band and 33 dBm, 50% PAE in DCS1800 band.

A millimeter-wave radio access system has a number of features that makes it appealing as one approach to broadband communications. However, for a millimeter-wave system to come into wide use, it must be miniaturized and the associated costs reduced. We have succeeded in realizing a compact 156 Mbps radio transceiver with a 38 GHz band optimizing RF architecture. We also adopted newly developed three-dimensional laminated MCMs using low cost plastic composite materials. It was confirmed in the initial experiments that this millimeter-wave wireless LAN equipment can cover a sufficient service area for broadband telecommunications in an indoor environment.

This paper first presents an active integrated antenna configuration designed for broadband mobile wireless access systems using the 25-GHz band. This active integrated antenna comprises a microstrip antenna array and RF front-end circuits adopting spatial power combining schemes for reduced power consumption of the power amplifiers. Furthermore, the antenna and RF circuits are integrated into each side of a thick copper backing plate and both are connected through microstrip line /slot transitions. The developed active integrated antenna achieves the output power of 14.6 dBm and a noise figure of less than 5 dB. The wireless system using the developed active integrated antenna achieves a 6-dB improvement in the packet error rate compared to that using a passive antenna with the same array design as the active integrated antenna. Furthermore, we obtained the first license of the active integrated antenna for commercial use in high-speed wireless communication systems in Japan.

This paper focuses on the investigation of RoF link noise influence in an ubiquitous antenna system, which is composed of multiple radio base stations (RBSs) deployed over the service area, central control station (CCS) and radio-on-fiber (RoF) link that connects RBSs to the CCS. The ubiquitous antenna system is capable of receiving multiple mobile terminals simultaneously operating at the same frequency channel by making effective use of joint detection. However, in the ubiquitous antenna system, since signals are transmitted from RBSs to CCS via the RoF link, the noise generated at the RoF link, such as relative intensity noise, inter modulation distortion, optical shot noise and thermal noise, may become dominant factors degrading the performance. The performance evaluations considering optical link noise is given by computer simulations. Computer simulation results show that more than 19 dB of RoF link E_b/N₀ is required for achieving sufficient performance.

Microstrip antennas on various Uniplane Compact Photonic BandGap (UC-PBG) substrates are investigated. Particularly, anisotropic characteristics of UC-PBG is studied and applied to the design of microstrip diplexer antennas. Moreover, an Embedded UC-PBG (EUC-PBG) scheme is presented to overcome the strong backward radiation caused by the conventional UC-PBG antennas. Such antennas demonstrate the improved radiation properties over the conventional UC-PBG antennas, and the evidence on surface wave suppression is also demonstrated. Experimental results show very good agreement with theoretical predictions.

The new hybrid antenna structures having external high-impedance-plane (HIP) shield are proposed. These antennas consist of normal patch or dipole antenna, working as a radiator, and HIP shield working as a reflector. The external HIP shield helps to reduce the undesired backward radiation. Generally, metal shield should be placed a quarter wavelengths apart from the antenna, but HIP shield can be placed close to the antenna and low profile structure can be obtained. In addition, compared with single-layer HIP antennas, having a patch surrounded by HIP structure, these hybrid antennas have the advantage of installation because the shielding effect can be obtained by attaching the external shield under the existing antenna. We fabricated HIP boards and combined with a microstrip patch or a regular dipole. The hybrid patch antenna with HIP shield improves the front-to-back radiation ratio (F/B ratio) similar to the single-layer HIP antenna or the hybrid patch with metal shield. But the dipole antenna with HIP shield, the F/B ratio is worse than the dipole with metal shield. These results indicate the TM mode antenna is suitable for the HIP shield in terms of the F/B ratio improvement.

We developed a phase controlled magnetron (PCM) with high DC-RF conversion efficiency and with phase control to steer a microwave beam in order to realize the final space Solar Power Station (SPS) system. For the PCM, we use injection locking technique and PLL feedback to anode current. We can stabilize and control a frequency and a phase of a microwave of the PCM. However, we have a power loss after the PCM for the SPS use because of a size of the antenna (> km) and of a microwave power (> GW). In order to decrease power loss after PCM, we newly propose a concept of "sub phase shifter" which can change only 1 or 2 bits of a phase and has low loss. We can keep high beam collection efficiency when we control a beam to a twice larger direction in the SPS system. With this concept, we developed a PCM array called SPORTS (Space Power Radio Transmission System) in FY2000 and FY2001 in Kyoto University.

Microwave Power Transmission (MPT) technology is one of the most essential parts for Solar Power Station/Satellite (SPS). We study on application of magnetrons as DC-RF converters for the MPT transmitting system. Magnetrons cost much cheaper, have much higher DC-RF efficiency over 70% and much lighter system weight per 1 watt RF output than semiconductor amplifiers although they have wider bandwidth of the fundamental frequency and spurious noises in various frequencies. Spurious noises are radiated from the transmitting system and interfere in the other communication systems both in space and on the Earth. The objective of this study is the improvement of the spurious noises generated from magnetrons. Experimentally, magnetrons driven by DC stabilized power supply had not only narrower bandwidth of the fundamental frequency but also lower spurious noise levels when filament current is turned off than when it is turned on. Some spurious noises are probably caused by the intermodulation between the low frequency spurious noises, which frequency is below 1 GHz, and the fundamental or the harmonics. We also verified that the harmonics levels of the measured magnetron in our measurement system were below -70 dBc, which are comparable to or better than those of some semiconductor amplifiers, and that the harmonics were not improved greatly when the filament current was turned off because the source of the harmonics is the distortion of the fundamental.

In this paper, a practical adaptive TuCM scheme is proposed, and its adaptive method is described. With some hardware considerations, a suboptimal optimization algorithm which shows that the number of fading regions is variable is put forward. The proposed adaptive TuCM comes within 3 dB of fading channel capacity, exhibits about 3 dB power gain over conventional adaptive TCM, and is easy to realize by hardware. Considering delay and channel estimation error, the BER performance of adaptive TuCM is analyzed and simulated. In the performance analysis, the method of data fitting is applied to obtain the BER expression for TuCM, and a fitting mathematical model is proposed. Results show that adaptive TuCM is very sensitive to delay and channel estimation error. To alleviate these problems, we proposed an improved power adaptation that can make adaptive TuCM practical.

A pilot needs operational information about wind over sea as well as wave height to provide safety of hydroplane landing on water. Near-surface wind speed and direction can be obtained with an airborne microwave scatterometer, a radar designed for measuring the scatter characteristics of a surface. Mostly narrow-beam antennas are applied for such wind measurement. Unfortunately, a microwave narrow-beam antenna has considerable size that hampers its placement on flying apparatus. In this connection, a possibility to apply a conventional airborne radar altimeter as a scatterometer with a nadir-looking wide-beam antenna in conjunction with simultaneous range Doppler discrimination techniques for recovering the wind vector over sea at low speed of flight is discussed, and measuring algorithms of sea surface wind speed and direction are proposed. The principle considered and algorithms proposed in the paper can be used for creation an airborne radar system for operational measurement of the sea roughness characteristics and for safe landing of a hydroplane on water.

An attenuation measurement system, which employs a traceable inductive voltage divider (IVD) at 1 kHz as a reference standard and dual channel intermediate frequency (IF) substitution method, is developed as an attenuation standard in the frequency range of 5 GHz to 12 GHz. The basic properties of the system are experimentally investigated and the expanded standard uncertainty of the system is estimated to be 0.0018 dB for 20 dB and 0.026 dB for 80 dB attenuation.

Electronics packaging evolution involves both systems, technology & materials considerations. In this paper, we present a novel 3D integration approach for system-on-package (SOP) based solutions for wireless communication applications. This concept is proposed for the 3D integration of a C band Wireless LAN (WLAN) RF front-end module by means of stacking LCP (Liquid Crystal Polymer) substrates using µBGA technology. LCP substrates fabrication, high Q inductor design and the associated physical based modeling are detailed. Then stacking techniques using µBGA technology is presented. Characterization and modeling of RF vertical board-to-board transition, using µBGA process are detailed and show that this vertical transition is suitable for C-band wireless communication applications.

A new technique to reduce the isolation network's size in a Marchand balun needed for perfect all-port matching and isolation is proposed. The proposed isolation circuit is realized using a coupled-line phase-inverter in place of the bulky 180line section that has been previously proposed. Analysis of the proposed circuit yields the required relationship between coupling coefficient and electrical length of the coupler. Based on the design equations, the circuit is experimentally demonstrated at 1.8 GHz and has shown excellent results. The obtained output return loss and isolation loss are more than 18 dB and 40 dB, respectively. The proposed balun was then applied to the application of a doubled-balanced ring-diode mixer. The designed mixer achieves a low conversion loss of 6 dB at its operating frequency, which is 1.5 dB lower than for a doubled-balanced diode mixer using a conventional impedance-transforming Marchand balun. The RF-IF and LO-IF isolations are well below 25 dB and 18 dB across 1 GHz RF operating bandwidth, respectively.

A technique for the design of circular- and racetrack-shaped NRD guide ring resonators was developed based on the mode coupling theory. Besides the operating mode, a parasitic mode is generated at curved sections of the resonator as a result of the mode conversion. Resonance of the NRD guide ring resonator is derived by characteristic equations of the coupled modes and then employed in making the design diagrams, which are useful for determining the dimensions of the ring resonators. It is shown that the discrepancy between the experimental results and previous theory can be resolved by using the present theory. Low loss, small-sized ring resonators with curvature radii of less than 5.3 mm were fabricated at 60 GHz and a band rejection performance of more than 30 dB was observed. Moreover, a procedure for the design of the channel dropping filter was developed and a 2-pole filter, which has great advantages such as a low insertion loss of 1.2 dB and a compact size smaller than that of a golf ball, was successfully developed by using two racetrack-shaped ring resonators.

The design, fabrication, and characterization of monolithic analog phase shifters based on barium-strontium-titanate (BST) coated sapphire substrates with continuously variable 180and 360phase-shift ranges are presented. The phase shifter using a single series resonated termination can provide 180phase shift with the chip area of 4 mm 4 mm. A double series resonated termination in a parallel connection can reach over 370phase shift with better than 6.8 dB-loss at 2.4 GHz. Also, an all-pass network phase shifter composed of only lumped LC elements was described here. This phase shifter demonstrated 160phase shift with an insertion loss of 3.1 dB 1 dB and return loss of better than 10 dB at 2.4 GHz. The total size of the phase shifter is only 2.4 mm 2.6 mm, which is the smallest reported BST phase shifter operating at S-band, to the best of the authors' knowledge.

In this paper we describe the investigation of design methodology of a planar duplexer consisting of BPFs using mixed tapped resonators. Firstly, we propose the planar duplexer consisting of bandpass filters (BPFs) using a tapped open-ended λ/2 resonator and a tapped λ/4 resonator. The duplexer is designed based on the general filter theory with narrow band approximation and tap-coupling technique. The actual duplexer is fabricated using a coplanar waveguide (CPW). Secondly, downsizing of the planar duplexer is carried out based on the BPF using stepped impedance resonators (SIRs). Lastly, another type of duplexer consisting of different BPFs using mixed tapped resonators is investigated in the same manner. The results of this study lead us to the conclusion that the design methodology is useful for realizing the high-performance planar duplexer fabricated without increasing the number of elements.

The millimeter wave bandpass filter using the Whispering-Gallery mode (WG mode) dielectric disk resonators is presented in this paper. A 4 stage maximally flat bandpass filter is constructed with the PTFE disk resonators. For the filter design, the coupling coefficients of this mode in the coupled disk resonators are calculated by an approximated separation of variables method. Furthermore, the external Q values of the disk resonator excited by a dielectric waveguide are investigated experimentally. Designed center frequency is 60 GHz and 3 dB band width is 150 MHz. Furthermore, as an attempt to improve the spurious characteristics, another filter structure which consists of some kinds of dielectric disk is tested. As a result, some spurious responses are reduced considerably.

On a transmission line lowpass filter fabricated on a printed circuit board using open-circuited microstrip straight-line stubs, the frequency at the edge of a passband or stopband tends to be higher than the frequency determined by the filter synthesis theory. One of the reasons for this is thought to be the interconnection of a low-impedance straight-line stub and transmission lines. The length of a constituent transmission line cannot be determined precisely because of the finite width. Therefore, as a means of avoiding the frequency shift between a trial circuit and a theoretical one, we first introduce a radial-line stub, and then show the equivalency of a radial-line stub to a straight-line stub in a range of zero to the first resonant frequency from the view point of their input impedances. Dimensional data of radial-line stubs corresponding to low-impedance straight-line stubs are investigated with respect to examples of three-, five- and seven-element Butterworth and Chebyshev filters. It was found that frequency characteristics of trial lowpass filters using radial-line stubs agree well with theoretical characteristics known as the Butterworth or Chebyshev.

We have developed a 2 GHz band superconducting 8-pole tunable quasi-elliptic function filter on sapphire substrate. The tunable filter has a sharp skirt characteristic by transmission zeros. And the tunable filter uses a low-cost substrate of sapphire. An adjustment of center frequency for the filter is realized by a tunable technique with a piezoelectric bending actuator. The tunable filter realized center frequency shift of 7.62 MHz with conditions of bandwidth change of 0.5% and ripple change of 0.25 dB. Center frequency of the 8-pole quasi-elliptic function filter agreed with the designed value. Given these features, a superconducting filter with a sharp skirt characteristic for next-generation mobile RF applications is expected to be realized by applying these filters.

Unloaded Q of an image-type dielectric resonator is studied with the simulation and experiment. It is shown that a gap between the dielectric resonator and the shield case reduces both the dielectric loss and conductor loss. The gap moves the electric and magnetic field distributions in the different directions, so that the two losses are reduced. A half-cut image-type resonator with a dielectric spacer inserted into the gap is measured to verify the concept. The unloaded Q is improved by about two times from that without a gap. The proposed structure gives a new packaging method of a dielectric resonator.

This paper proposes a novel extraction method of line parameters for multi-coupled lines on high-speed and high-density PCBs, where it uses TDR measurement in time domain and S-parameter measurement in frequency domain. The accuracy of the proposed method have been verified experimentally by comparing the crosstalk noise in the time domain, where (1) the proposed method extracts RLGC matrices by measuring the test pattern, (2) the crosstalk noise is obtained through SPICE simulation using the extracted RLGC matrices, and (3) the SPICE-simulated crosstalk noise is compared with the measured crosstalk noise. From the crosstalk noise comparison, the proposed method is proven to be very accurate. For N-coupled lines, the proposed method doesn't require expensive 2N-port probe for N-coupled lines but only two-port probe, which provides a simple, accurate, and economic extraction method of line parameters for multi-coupled line on the PCB. In the early stage of PCB design, the proposed method is very useful, because it extracts accurate interconnection parameters of each test board and enables to compensate various side effects due to the variation of PCB fabrication process. Also, the proposed method is necessary to analyze the signal integrity of future high-density and high-speed digital system on PCBs.

This paper presents the design consideration of a polarization-transformation transmission filter, which is composed of a multilayered chiral slab. The optimal material parameters and thickness of each layer of the slab can be determined by using a genetic algorithm (GA). Substituting the constitutive relations for a chiral medium into Maxwell's equations, the electromagnetic field in the medium is obtained. A chain-matrix formulation is used to derive the relationship between the components of the incident, the reflected, and the transmitted electric fields. The cross- and co-polarized powers carried by the transmitted and reflected waves are represented in terms of their electric field components. The procedure proposed for the design of a polarization-transformation filter is divided into two stages. An ordinary filter without polarization-transformation and a polarization-transformation filter for the transmitted wave are designed with a multilayered non-chiral slab and a multilayered chiral slab at the first and the second stages, respectively. According to the specifications of the filters, two functionals are defined with the transmitted and reflected powers. Thus the optimal design of a polarization-transformation filter with the multilayered chiral slab is reduced to an optimization problem where the material parameters and thickness of each chiral layer are found by maximizing the functionals. Applying the GA to the maximization of the functionals, one can obtain the optimal material parameters and thicknesses of the multilayered chiral slab. Numerical results are presented to confirm the effectiveness of the two-stage design procedure. For three types of multilayered chiral slabs, optimal values of refractive indices, thicknesses, and chiral admittances are obtained. It is seen from the numerical results that the proposed procedure is very effective in the optimal design of polarization-transformation filters for the transmitted wave.

Whispering-Gallery mode resonator method has been presented for complex permittivity evaluation of low loss dielectric materials in millimeter wave region. As a problem, it has been found that the evaluation error slightly dependens on the frequency for a sample. It comes from approximated analysis which is used in the procedure. In this paper, a mode-matching method is applied to this evaluation technique to have improvement of the measrued results. It is confirmed experimentally that reliability of the presented method is improved for the millimeter wave permittivity measurement.

Two type measurement methods of the unloaded Q-factor of a microwave resonator, the insertion loss method and the return loss method, are reexamined theoretically and compared experimentally. An error formula is derived to estimate the errors between the unloaded Q-factors measured by the two different methods. Measured results of a stripline resonator verified well the derived formula, and proved that the return loss method is more accurate and reliable than the traditional insertion loss method.

So far, a lot of analyses have been performed on the edge-guide mode isolator with one short edge. However, the detailed characteristics such as the influence of shape of a metal strip and the thickness of a ferrite substrate have not been revealed. This paper clarifies the influence of the structure on the frequency response both experimentally and numerically. The numerical analysis is performed by the FDTD method. The numerical results indicate that the frequency response does not depend on the thickness of ferrite substrate but does on the shape of the metal strip. Furthermore, based on the numerical results, the experiment is carried out on the prototype isolator. All the results provide a theory of the optimum design on the isolator.

This paper newly proposes a hollow ferrite waveguide which consists of a microstrip line loaded on two ferrite slabs with adjacent air gap. Dispersion relation of magnetostatic surface wave in the waveguide is derived by the two dimensional analysis, and reciprocal behavior for parallel bias magnetic field and nonreciprocal behavior for antiparallel bias magnetic field are shown. Propagation characteristic of magnetostatic surface wave in the hollow ferrite waveguide are experimentally demonstrated under both parallel and antiparallel bias magnetic field directions. Strong nonreciprocal behavior in the hollow guide was found for case of antiparallel bias field configuration. These experimental results are mostly in agreement with the dispersion diagram. A nonreciprocal four port junction is demonstrated as an application of the hollow ferrite waveguide.

A general circuit model of a filter having one cross coupling path is analyzed, and a new theory is developed for the design of a filter with transmission zeros in its stopband. By using the derived formulas, the reactance element values in the cross coupling path are determined readily. The transmission zeros can thus be assigned at desired frequencies. Various design examples are provided, together with simulated results, which validate the proposed theory.

A microwave variable delay line using a membrane impregnated with liquid crystal was newly fabricated. By employing the membrane impregnated with liquid crystal to the liquid crystal layer of the delay line, the phase-shift response becomes fast independently of the liquid crystal thickness. Experimental results show that the phase-shift response time of 33 ms, which is two orders of magnitude faster than that of a conventional one, is obtained. The new delay line also exhibits a 270-degree phase-shift and non-dispersive delay characteristics over a wide microwave-frequency range, although a higher control voltage is needed. It is also clarified that the phase-shift characteristics to the control voltage depend on the pore size of the membrane. This membrane impregnated with liquid crystal also enables us to make the variable delay line thin and flexible.

A novel periodic element for the sandwich photonic bandgap (PBG) structure named as H-shape element is presented in this paper. Sandwich PBG structure is a kind of PBG structure whose periodic lattice is buried in the midmost of the substrate. There's no requirement to drill or suspend the substrate. The new H-shape element is made of a central block connected with a long and narrow block on either side, and possesses a quite deep forbidden gap, whose width and depth can be tuned by varying the dimension of the central block. Theoretical results, as confirmed experimentally, indicate that the maximum insertion loss in the stopband is up to 80 dB. This sandwich microstrip structure can be constructed using conventional printed-circuit-board fabrication processes and integrated with other microwave components in a multilayered circuit. An improved notch filter with chirped central blocks is presented. The length of the filter is reduced by 16.7%, and the fractional bandwidth is increased by 8.1% compared with that of a conventional sandwich microstrip notch filter on the same substrate. The experimental results agree well with the finite difference time domain (FDTD) simulations.

In this paper, a predistorter using low frequency intermodulation (IM) signals is proposed. The harmonic generator of the proposed predistorter that consists of a hybrid coupler and four diodes biased separately extracts a second order low frequency IM signal. And with multiplication of second order IM signals, fourth order IM signal is obtained. A vector modulator, modulate fundamental signal with low frequency IM signals, generates predistortion IM signals and controls amplitude/phase of them with modulation factors. As a result, this predistorter is suppressed individual order intermodulation distortion signals of power amplifier effectively. The suggested predistorter has been manufactured to operate in Korea PCS base-station transmitting band (1840-1870 MHz). The test results show that the third order IM is cancelled more than 20 dB and the fifth order IM is cancelled about 10 dB for CW two-tone signals. Also, it's improved the adjacent channel power ratio (ACPR) more than 10 dB for CDMA (IS-95) signals.

A grooved circular cavity is designed for the millimeter wave measurements of dielectric substrates. The grooves are introduced to separate the degenerate TE_01p and TM_11p modes in circular cavities. A rigorous mode-matching method is used to investigate the influence of grooves on both the TE_01p and TM_11p modes. The dimensions of the grooves are determined from the numerical results. Comparative experiments of circular cavities with and without grooves validate the design method.

The frequency dependence of surface resistance R_s of high temperature superconductor (HTS) films are measured by a novel measurement method using four TE_0mp modes in a sapphire rod resonator. At first, a loss tangent tan δ of the sapphire rod and R_s of the HTS films are evaluated separately from the results measured for the TE₀₂₁ and TE₀₁₂ modes with close resonant frequencies. Secondly, R_s values at two different resonant frequencies for the TE₀₁₁ and TE₀₂₂ modes are measured using a well-known relation for sapphire tan δ/f = constant, where f is a frequency. R_s values of HoBa₂Cu₃O_7-x thin films were measured in the frequency range of 10 to 43 GHz by using four sapphire rod resonators with different sizes. As a result, it is found that these measured results of R_s have a characteristic of frequency square.

A compact high-temperature superconducting (HTS) bandpass filter (BPF) using coplanar waveguide (CPW) meander-line parallel-circuited resonators is proposed for microwave receiver applications. The design theory is presented based on a conventional filter theory with J-inverters. Also, analytical and numerical studies of the meander-line resonator are carried out in terms of equivalent circuit values, the resonant frequency, and the unloaded Q. Two- and four-stage 0.05 dB ripple Chebyshev BPFs at 2 GHz with relative bandwidth 60 MHz are fabricated with the metalorganic deposition (MOD)-derived YBCO films on LaAlO₃ substrates and their performance are demonstrated. The measured frequency characteristics and the unloaded quality factors agree well with the theoretical and numerical results and the validity of the design theory is confirmed.

The wavelet transform approach is applied to the boundary element method (BEM) for solving electromagnetic scattering from multiple scatterers. A matrix equation is first obtained by the BEM where the elements of the impedance matrix are arranged as smooth as possible along its columns and rows. Consequently, the matrix is divided into several minor matrices with continuous and periodic structures along their columns and rows. Next, the matrix equation is transformed by a wavelet matrix to sparsify the impedance matrix. The wavelet matrix is constructed to consist of minor wavelet matrices and makes the minor matrices of the impedance matrix be transformed independently. This approach reduces both the computation costs of performing the wavelet transform and solving sparse linear equations if it is compared with the conventional one.

A new formula on the Hermite expansion is presented in an explicit form. An application of the formula is given to a random boundary value problem: a plane wave reflection from a flat plane, of which position is randomly distributed in the normal direction, is presented. Several numerical results are given for a verification of the formula and for a discussion of the exact behavior of the fluctuation part of the reflection power.

It is shown that the glass structure change is a simple and widely applicable method to modify refractive index locally in various glass fibers. A small part of a glass fiber is heated immediately to above its melt temperature by arc discharge, and then the molten fiber undergoes rapid cooling, which freezes the change of the glass structure. Therefore the refractive index of the fiber is decreased partially by the glass structure change induced by rapid solidification. The index reduction in a fiber fabricated from multicomponent glasses is estimated to be more than 0.006. To clarify that rapid solidification works for various glasses including silica glasses, long-period gratings are written in a standard telecommunication fiber with various discharge currents and times. The peak loss of more than 25 dB is obtained within only 6 periods. The index change can be adjusted by the discharge conditions. The gratings are not degraded by heating the whole gratings at 700C for 2 hours, and are highly temperature-stable. It is shown that resonance wavelengths can be tuned by controlling the heating temperature and heating time.

Segmentation of a dielectric resonator enables one to control its spurious property. When a dielectric plate is divided into some planar pieces, the effective permittivity does not change appreciably along the divided plane, while it decreases quite an amount perpendicular to it. This anisotropy is useful for shifting the resonant frequencies of unwanted modes of a dielectric resonator. Since its eigen modes have their own electric field distribution, segmentation of a resonator along the electric line of force of a certain mode will not affect its resonant frequency. When the type of segmentation is changed, we can select the wanted mode, and thus control the resonant frequencies of the unwanted modes. Calculated results with an EM field simulator and experimental results of controlling the resonant frequency are shown for divided dielectric resonators.

In this paper, design of a new analog CMOS rank-order extractor with input expandable capability is described. An rth rank-order extraction is defined that identifies the rth largest magnitude of input variables, which is useful for fuzzy controller and artificial neural networks. The architecture is realized by using maximum circuit, winner-take-all circuit, and some auxiliary circuits. The limitations and design considerations of these circuits are analyzed in this paper. An experimental chip with seven inputs is fabricated using a 0.5 µm CMOS double-poly double-metal technology. The results of measurement show the extractor with 2 µA precision, and each rank-order extraction has about 2 µs response time. The power dissipation of the experiment chip under test includes input/output pads that has 7.2 mW for 3.3 V supply voltage. The chip area of the extractor is 600 µm 700 µm.

It is very difficult to simultaneously achieve power and cost reductions in address-driver circuits of a plasma-display panel (PDP) unit in which an energy-recovery scheme utilizing the resonance of a series-connected inductor and electrode parasitic capacitors is used. This is because an increase in parasitic capacitance and high-speed circuit operation become necessary as the display panel becomes larger in size and higher in resolution. In particular, low-power operation of address-driver ICs is key to avoiding the installation of heat sinks on the ICs. We propose herein new power-dispersion methods that can greatly reduce the power dissipation of address-driver ICs even when large parasitic capacitance is driven at high speed. The proposed methods enable a reduction in the power dissipation of address-driver ICs without deteriorating the operational speed by dispersing their powers into external resistors, and by supplying power to address-driver ICs in two voltage steps during both rising and falling time intervals when the address changes. Our results indicate that the power dissipation of address-driver ICs and the total cost of the address drive unit of a plasma-display panel can be reduced to 29% and 53%, respectively, compared with those of the ICs and the unit that are driven by the conventional address-driving method.