Kazuoki Matsugatani

A novel FET model including an illumination intensity parameter for simulation of optically controlled millimeter-wave oscillators

This paper demonstrates an illuminated FET model including an illumination-intensity parameter for simulation of optical characteristics of microwave and millimeter wave integrated circuits (MMICs). Modeling for an illuminated GaAs MESFET and an InP high electron-mobility transistor (HEMT), and analysis and experimental results from optically controlled microwave and millimeter-wave hybrid integrated circuit (HIC) and MMIC oscillators are discussed. The proposed illuminated FET model was able to explain the photoresponse of both the GaAs MESFET and the InP HEMT, and the photooperation of their circuits.

Surface wave distribution over electromagnetic bandgap (EBG) and EBG reflective shield for patch antenna

Surface wave distribution over electromagnetic bandgap (EBG) plate is measured and suppression of surface wave propagation over the EBG is investigated. We used a micro current probe that detects Hfield strength of the propagating transverse magnetic (TM) microwave up to 6 GHz. By scanning with the probe over the EBG, we visualized surface wave distribution at various frequencies. This visualized map shows that the EBG plate suppresses the surface wave propagation within the bandgap frequency. We utilized this effect for the antenna reflective shield. By combining the EBG with a microstrip patch antenna, this EBG works as a reflective shield and the front-to-backward radiation ratio of antenna is increased. In this experiment, we fabricated three types of shield board: mushroom type of EBG that has hexagonal textured patches connected with via-holes, textured surface without via-holes, and plane metal. By comparing the surface wave distributions and beam patterns of antenna with various shields, we found that the visualized map of TM surface wave gives us direct and intuitive information and helpful tips in designing the EBG reflective shield for patch antenna.

Microstrip patch array antenna coupled with parasitic patches using one dimensional EBG structures

A novel planar microstrip array antenna is proposed and fabricated. This antenna is composed of one active or fed microstrip patch and two parasitic microstrip patches. Two parasitic patches are coupled with active patch via one-dimensional electromagnetic bandgap (1D-EBG) structures. 1D-EBG structures, maintaining the resonation of active patch, supply microwave power to parasitic patches then no feeding circuits are needed and compact antenna is realized. Because of enhancement of coupling between active and parasitic patches, this antenna performs high gain of 10.8 dBi at 5.8 GHz, comparable to ideal three active patch array.

Broadband Planar Antenna Combining Monopole Element with Electromagnetic Bandgap

New structure of broadband planar antenna, combining monopole elements with electromagnetic bandgap (EBG) structures, is proposed. The antenna has a simple single layer structure and unique beam pattern. Antenna is fabricated on a surface of a single layer dielectric substrate and back side of the substrate is covered with metal layer. At the center of the substrate, an inverted L monopole strip is fabricated and on both sides of this monopole, EBG unit cells are placed. By tuning monopole length and EBG bandgap frequency, the monopole resonates even if metal layer exists close to the monopole radiator. Three types of EBG, one dimensional (1D), square two dimensional (2D) and hexagonal 2D, are tested. By combining monopole strip with hexagonal 2D-EBG, the bandwidth of prototype antenna, whose return loss is less than 10dB, is 840MHz in 5GHz band. To control beam patterns of antenna, parasitic elements are placed close to the monopole radiator and EBGs. These parasitic elements work as directors of quasi Yagi-Uda antenna and radiation gain at lower tilt angles is improved.

Optical Tuning of CPW InP MMIC Oscillator by Illumination from Back Side of Substrate Using 1.5 μm Semiconductor Laser

This paper describes the experimental results of the optically controlled InP based MMIC oscillator with illumination from the back side of the wafer. The oscillator consists of the InP HEMT and the CPW. The optical frequency shift of the InP MMIC oscillator illuminated from the front side and the back side with 1.5 μm optical source were 28 MHz and 46 MHz around 38 GHz, respectively. It was found that enhancement of the optical tuning with the 1.5 μm laser can be realized by the illumination from the back side of the InP substrate.

A broadband planar patch array resonator antenna

A new microstrip antenna with an improved bandwidth is discussed. The new antenna is built with an array of patches on a thin grounded substrate. The number of patches and the individual patch size can be adjusted for desired antenna performance. A twelve-cell patch array resonator with a unit cell size of 5.5 mm and the total antenna area of 25times16 mm2 was fabricated on a 1.27 mm-thick substrate with dielectric constant of 9.8 for a measurement at 6.8 GHz. The measured planar patch array resonator antenna showed 10-dB return-loss bandwidth of 6.6 percent compared to 1.7 percent of a single square patch antenna.

Automotive Radar Signal Source Using InP Based MMICs

This paper describes a millimeter wave signal source for automotive radar developed with microwave/millimeter-wave integrated circuits (MMIC). It describes the principles of the frequency modulated continuous wave radar, the structure and performance of the high electron mobility transistors, the design of the MMIC and the performance of the signal source. Potential applications for millimeter wave radar include intelligent cruise control and collision avoidance systems.

Critical Layer Thickness of n-In0.52Al0.48As/In0.8Ga0.2As/In0.52Al0.48As Pseudomorphic Heterostructures Studied by Photoluminescence

Photoluminescence (PL) analysis on n-In0.52Al0.48As/In0.8Ga0.2As/In0.52Al0.48As/InP pseudomorphic heterostructures grown by molecular beam epitaxy has been carried out to investigate the critical layer thickness. Crystal quality degradation is followed by the relaxation of the lattice-mismatched layer. The critical layer thickness for this material system that is measured by PL is found to agree with the value from the energy balance model.