In this paper, a novel flexible photonic microwave filter architecture based on the use of laser arrays and the periodicity of N N arrayed waveguide gratings (AWG) optical response is proposed. Independent filter response coarse and fine tuning as well as reshaping of each transversal filter response have been experimentally demonstrated showing an excellent agreement with theory.

This paper presents a novel mm-wave and THz device concept, with a detailed physical modeling and quantitative performance evaluation, called as CW HTS (high temperature superconductive) photomixer/antenna. Optical heterodyne photomixing in the DC-biased HTS strip has been employed to create mm-wave and THz signal, and the size of strip on the grounded dielectric substrate is designed to have an efficient broadside radiation. Incorporating the HTS microstrip configuration as both photomixing media and radiation element at the same time not only increases the CW photocurrent but also the radiation power, while it reduces the radiation loss associated with the patch antenna. Two possible configurations called as longitudinal and transversal will be introduced and their photomixing efficiency and output radiation power will be compared. The detailed analysis along with the optimum design of the geometrical parameters of the microstrip structure shows that the transversal scheme exhibits higher radiation power. The typical nW output power can be obtained by mW laser pump power for frequencies up to the gap frequency of the HTS material. The output power of the proposed device is theoretically higher than the experimentally available data from a Low-Temperature-Grown (LTG) GaAs photomixer integrated with dipole or bow-tie antenna reported in the literature.

We report on the first demonstration of single sideband (SSB) modulated time stretch system. In addition, we present an analytical model relating the system performance to the phase and amplitude mismatches in the SSB modulator. The results show that, fortuitously, the system is tolerant to such mismatches. In particular, using commercially available components,the dispersion induced power penalty can be kept below 2.5 dB over 4-20 GHz bandwidth for any stretch factor. The experiments demonstrate 120 Gsample/s real-time capture of a 20 GHz SSB-modulated microwave signal.

This paper presents a modified microwave radio-thermometer (MRTM) with material characteristic estimator and multiple temperature conversion tables to measure subcutaneous temperature of a living body. This estimator provides a temperature retrieval unit with material characteristics such as permittivity, conductivity, thickness and geometry of the living body. The temperature retrieval unit with multiple temperature conversion tables can select one of the tables and compute temperature value corresponding to measured radiation power. In the experiments, it was shown that the radio-thermometer could reduce measurement errors of about 0.82 to 7.68 for the cases of distilled water and mixed liquid # 5 with thickness of 29.5 cm and 9.5 cm at the temperature of 37.

An ultra-small (0.4 0.4 mm2) radio frequency identification (RFID) chip named µ -chip has been developed for use in a wide range of individual recognition applications. The chip is designed to be 0.06 mm thick so that it can be applied to paper and to thin paper-like media, which have been used widely in retailing to create certificates that have monetary value, as well as to token-type devices. The µ-chip has been designed and fabricated using 0.18 µm standard CMOS technology with 3-layer aluminum metallization. The chip has a 128-bit memory. The memory data is easily read by applying a 2.45 GHz microwave radio frequency identification circuit technique. The minimum operating voltage of the chip's digital circuits is 0.5 V. This chip has attached to a thin-film external antenna. The chip terminals are connected to the antenna by an anisotropic conductive film (ACF). This type of structure results in a 0.15 mm thin transponder. The maximum communication distance between the µ -chip and a reader is 300 mm at a reader power of 300 mW.

In this paper, we propose a passive imaging system for noise-source identification using time-domain waveform sampling. The fundamental concepts are based on optics theory. A waveform of a diffracted field over an entrance pupil is obtained by a digitizing oscilloscope. The phase distributions over the entrance pupil for each frequency are calculated by using Fourier transform of the acquired waveforms. Thus, an image on the focal plane is reconstructed by using inverse Fresnel transform. The most significant advantage of the proposed method is that an image for each frequency can be obtained separately. We confirmed that the proposed method can be used for practical noise-source identification, by experimentally obtaining images for an emission from personal computers.

Antennas for Japanese terrestrial microwave relay links have been developed since the1950's and put into commercial use up to now in Japan. In particular, the path-length lens antennas developed in 1953 represents a monumental achievement for terrestrial microwave relay links, and the offset antenna for 256 QAM radio relay links developed in 1989 has the best electrical performance in the world. This paper reviews the antennas for Japanese terrestrial microwave relay links that have historical significance and describes the antenna design technologies developed in Japan.

Fundamental perspective of high power devices and amplifiers for use in wireless communication systems are described in this paper. First, high power devices and device modeling techniques are presented, focusing on the emerging device technologies such as wide bandgap devices (GaN, SiC) and SiGe devices. Then the commercially available device, circuit and system simulators for wireless communication applications are introduced. Recent active load-pull measurements have made a remarkable progress in fundamental, harmonic, and envelope frequencies for high efficiency and low distortion designs. In addition, pulsed DC/RF and on wafer load-pull measurements have also become popular, which are briefly reviewed. Finally the advances in high power amplifier design techniques for achieving high efficiency and low distortion are presented.

A phased array behavior of a unilaterally coupled active antennas has been investigated. The active antenna is composed of a patch antenna and a parallel feedback type oscillator which can be coupled unilaterally to other oscillators without other nonreciprocal components. Numerical calculations of the reduced equations describing the behavior of the coupled oscillators array demonstrated that the phase differences between the oscillators can be varied up to about π/2 by giving the frequency changes from the injection locking frequency to the oscillators except of the first one. The oscillator mounted with the varactor diode for wide tuning range exhibited the property suitable for constructing the unilaterally coupled array. In the experiments at X-band, the electromagnetic wave radiated from the five element array was successfully scanned.

In the FDTD simulation of microwave circuits, a device in very small size compared with the wavelength is often handled as a lumped element, but it may still occupy more than one cell instead of a wire structure without volume routinely employed in classical extended FDTD algorithms. In this paper, two modified extended FDTD algorithms incorporating a lumped element occupying more than one cell are developed directly from the integral form of Maxwell's equations based on the assumption whether displacement current exists inside the region where a device is present. If the displacement current exists, the modified extended FDTD algorithm can be represented as a Norton equivalent current-source circuit, or otherwise as a Thevenin equivalent voltage-source circuit. These algorithms are applied in the microwave line loaded by a lumped resistor and an active antenna to illustrated the efficiency and difference of the two algorithms.

A large part of our daily lives is spent surrounded by buildings and other structures. In this paper, we used an infinitelength, multilayered cylindrical model to rigorously analyze the microwave specific absorption rate (SAR) of a human standing near a 90corner wall. At frequencies above 1 GHz, the interactions between the microwaves, the human body (including layer resonance), and the corner cause complex changes in the average SAR. We have shown numerically that the SAR with a corner present is up to four times larger than when there is no corner, and that the average SAR of TE waves at frequencies below 1 GHz is up to 10 times greater than when there is no corner.

To measure temperature dependent complex permittivity of dielectric materials, a rectangular cavity resonator with a heating system has been developed. In the experiment, microwave power with the frequency of 2.45 GHz is applied to heat the dielectric material. In order to reduce the error of the complex permittivity of dielectric material obtained from the perturbation method, an electromagnetic (EM) field simulator is applied which uses the Transmission Line Modeling (TLM) method. The uniformity of the temperature is also discussed by the use of heat transfer equation which applies the results of TLM simulation. It is found from the results that the accurate temperature dependence of complex permittivity of the material can be obtained by the method presented here.

As an RF high Tc superconducting (HTS) front end for a microwave receiver, we propose a new design method for the broadband matching circuit composed of coplanar waveguide (CPW) meanderline resonators connecting a slot antenna with CMOS low noise amplifier (LNA). The parameters of the antenna sections with matching circuit are calculated and simulated with the circuit simulator and electromagnetic field simulator. CMOS LNA was designed and its input and output impedances and noise figure were obtained by SPICE simulation.

An attempt to derive the lethal dose for mice was made at 2.45 GHz for whole body exposure. Based on a numerical dosimetry result and an experimental death rate investigation, the lethal dose was estimated to be a whole body averaged specific absorption rate (SAR) with a level at double the mouse's basal metabolic rate.

A 4-12 GHz 2 W GaAs HFET amplifier has been developed. It employs two novel circuit design techniques. One is a pre-matching circuit for dual gate-bias feed. It is comprised of two shunt LCR circuits, which makes dual gate-bias feed possible. The other one is a tapered power splitting/combining FET (tapered PS/PC FET), which makes amplitude and phase imbalance between FET cells small over a wide bandwidth. In this paper, the schematic diagram and impedance characteristic of the pre-matching circuit for dual gate-bias feed are described first, showing the conditions that the impedance of FETs becomes purely resistive. Then the amplitude and phase imbalance between FET cells are compared by electromagnetic simulation for both the conventional and tapered PS/PC FETs, demonstrating that the tapered PS/PC FET has smaller amplitude and phase imbalance. Furthermore, the MSG/MAG are compared by experiment for both FETs, confirming that the tapered PS/PC FET has higher MSG/MAG. Finally, the design, fabrication, and performance of the 4-12 GHz 2 W GaAs HFET amplifier using the pre-matching circuit for dual gate-bias feed and tapered PS/PC FETs are presented to make sure that two novel circuit design techniques introduced in this paper are useful for the design of wideband lossy match power amplifiers.

An L-Band high efficiency and low distortion multi-stage amplifier using self phase distortion compensation technique is presented. In this amplifier, the bias condition of the driver-stage transistor is tuned to compensate the phase distortion of the power-stage transistor, and the load and source impedances of the driver-stage and power-stage transistors are optimized to achieve the maximum efficiency with a specified adjacent channel leakage power (ACP) for multi-stage amplifier. The developed amplifier achieves a power added efficiency (Eadd) of 42.8% and an output power (Pout) of 26.8 dBm with an ACP of -38 dBc at 1.95 GHz for wide-band code-division multiple-access (W-CDMA) cellular phones.

The cutoff filter and circular window are critically important elements of circular waveguide TE11 mode transmission systems, but no detailed analysis of their characteristics has yet been undertaken. In order to gain a detailed understanding of return loss and other frequency characteristics, one must analyze the electromagnetic (E-M) fields in the waveguide cavity to the cutoff domain and higher mode oscillations. In this work we present a theoretical analysis employing a method in which E-M fields are represented in the form of transmission equations, and show that the results are in remarkably close agreement with experimental results obtained from a prototype device. It is also demonstrated that the results obtained by the proposed method are far more accurate than those obtained using conventional approximation theory.

An L-band low quiescent current and low distortion SiGe heterojunction bipolar transistor (HBT) driver amplifier having a self base bias control circuit is described. Since the size of this bias circuit is small and it does not need an external control circuit, it is easy to be integrated with the driver amplifier on a single chip. According to the output power level, the self base bias control circuit, which is the combination of a constant base voltage circuit and p-metal oxide semiconductor (MOS) FET current mirror with a constant current source, automatically controls the base voltage, and allows low quiescent current at low output power level and low distortion at high output power level. The simulated results show that the driver amplifier having the self base bias control circuit achieves 1 dB power compression point (P1 dB) improvement of 2.4 dB compared with the driver amplifier having a conventional constant base voltage under the same quiescent current condition. The fabricated driver amplifier with the proposed bias circuit shows high P1 dB of 15.0 dBm with low quiescent current of 15.3 mA.

A novel common emitter common collector transistor pair (CECCTP) mixer is presented. A LO pumped CECCTP enables even harmonic mixing operation, and a balanced CECCTP mixer configuration enables the suppression of both 2fLO and fIM2 which are undesirable component for direct conversion mixer. A 2 GHz-band balanced CECCTP mixer is fabricated in SiGe HBT process, and the direct conversion characteristics are measured. It performs conversion gain of 8.8 dB, NF of 14.9 dB and IIP2 of 42.3 dBm when LO power is -6 dBm, supplied voltage is 3 V and current is 5 mA.

We have measured the non line-of-sight (NLOS) propagation characteristics of microwave frequencies in an urban environment with a base station antenna situated well above the surrounding buildings. When these characteristics are compared with the results of measurements made in the same environment with a low base station antenna height, it can be seen that with a low base station antenna height the attenuation coefficient varies greatly between line-of-sight (LOS) and NLOS environments, whereas with a high base station antenna height there is no variation of this sort. This is because the waves arriving NLOS environments from a high base station antenna do so primarily as a result of rooftop diffraction, and the path loss does not vary much over regions of equal distance between the base station and mobile station. We have confirmed that the frequency characteristics of relative loss in NLOS environments with a high antenna height follow a relationship of 22.8 log f, which is more or less the same as the characteristic for the UHF band. By modifying the frequency terms of the Sakagami model (used for UHF band) based on this trend to allow it to handle microwave frequencies, a close correspondence is seen between the results of actual measurements and the values predicted by the extended model.