High Dynamic-Range and Very Low Noise K-Band p-HEMT LNA MMIC for LMDS and Satellite Communication

An excellent noise figure and high linearity, K-band p-HEMT LNA MMIC, that incorporates single-bias configuration and negative feedback circuit, has be en developed for LMDS (Local Multi-point Distribution Service) and satellite communication. The third order intercept point (IP3) of this MMIC is 20 dBm, while output power at 1-dB gain compression is 8.5 dBm. The IP3 and noise figure is 19.5 +/- 1 dBm and 1.8 +/- 0.2 dB, respectively, at frequencies between 24 and 32 GHz. The die size of the MMIC is 1.9 mm. This MMIC shows a potential reliable application in high-speed wireless access system

Zero-field and Larmor spinor precessions in a neutron polarimeter experiment

We present a neutron polarimetric experiment where two kinds of spinor precessions are observed: one is induced by different total energy of neutrons (zero-field precession) and the other is induced by a stationary guide field (Larmor precession). A characteristic of the former is the dependence of the energy-difference, which is in practice tuned by the frequency of the interacting oscillating magnetic field. In contrast the latter completely depends on the strength of the guide field, namely Larmor frequency. Our neutron-polarimetric experiment exhibits individual tuning as well as specific properties of each spinor precession, which assures the use of both spin precessions for multi-entangled spinor manipulation.Comment: 12 pages, 4 figure

Superconductivity of Quasi-One-Dimensional Electrons in Strong Magnetic Field

The superconductivity of quasi-one-dimensional electrons in the magnetic field is studied. The system is described as the one-dimensional electrons with no frustration due to the magnetic field. The interaction is assumed to be attractive between electrons in the nearest chains, which corresponds to the lines of nodes of the energy gap in the absence of the magnetic field. The effective interaction depends on the magnetic field and the transverse momentum. As the magnetic field becomes strong, the transition temperature of the spin-triplet superconductivity oscillates, while that of the spin-singlet increases monotonically.Comment: 15 pages, RevTeX, 3 PostScript figures in uuencoded compressed tar file are appende

Manufacture of dense sintered bodies containing silicon nitride

Sintered bodies containing 1-32.5 Si oxide and 1.5 wt.% SiC (Si oxide/SiC wt. ratio 3/2) are prepared and kept in a 10-3000 kg/2 sq. cm. N (g) atmosphere at 1500-2300 degrees, while simultaneously maintaining the CO (g) partial pressure around the body lower than the nitrogenation equil. pressure to give a dense sintered body. The prepared dense sintered body has high strength at high temperatures. Thus, SiC 40, oxide 30 and Si3N4 30 wt% were fired to a body which was kept in 1500 kg/sq. cm. N (g) for 20 h at 2000 degrees to give a dense sintered body having high bending strength at high temperatures

Effects of Fe2O3 addition on the nitridation of silicon powder

The reaction of silicon powder and nitrogen was studied in the range of 1300-1400 C. When an addition of Fe2O3 was more than 0.8wt%, the reaction was linear and compared to samples with no Fe2O3, the reaction velocity increased 5 to 10 times. The reactions were mediated by the process of peeling and cracking in a thin layer of Si2N4 formed on the silicon particles or on the surface of the Fe-Si melts. As the addition of Fe2O3 increased, the reaction activation energy for highly pure samples decreased. Fe2O3 which exceeded the Si3N4 solubility limits was finally converted to d-Fe

Structure of isomeric states in 66As and 67As

Strong residual correlations between neutrons and protons in N ~ Z systems can lead to unusual structure. Using the spherical shell model, we show that a low-excitation shape isomer can occur in the odd-odd N=Z nucleus 66As. This extends the picture of shape coexistence beyond even-even nuclei. Furthermore, it is demonstrated that in 66As and in the N=Z+1 nucleus 67As, a new type of isomer, which we term j-isomer, can be formed. The underlying mechanism for the isomerism formation is structure change in the isomeric states, which involves either an alignment of a neutron-proton pair from the high-j intruder orbitals, or a simultaneous occupation of these neutron and proton high-j orbitals.Comment: 11 pages, 2 figure