Phenomenological Implications of the Topflavor Model

We explore phenomenologies of the topflavour model for the LEP experiment at $m_{_Z}$ scale and the atomic parity violation (APV) experiment in the $C_s$ atoms at low energies. Implications of the model on the $Z$ peak data are studied in terms of the precision variables $\epsilon_i$'s. We find that the LEP data give more stringent constraints on the model parameters than the APV data.Comment: 23 pages (including 5 .eps figs), ReVTeX, the 1st revised version, to appear in Phys. Lett.

High-Gain Amplifier Module Integrating a Waveguide into the Module Case for Millimeter Wave Applications

A high-gain amplifier module with integrated waveguide (WG) has been presented for millimeter wave applications. In order to improve the isolation between the amplification stages in the multi-stage amplifier module, an isolated WG is integrated into the module case. It is possible to effectively suppress the oscillation occurring in the high gain stage. Microstrip line (MSL)-to-WG transitions are designed and fabricated on a 5 mil thick RT5880 substrate for interconnection of the isolated WG, input/output WG and amplifier PCB in a cascaded two-stage high gain amplifier module. The transition loss of −0.44 dB is obtained at 40 GHz and return-loss (S11) bandwidth below −10 dB is from 34.1 to 50 GHz. The fabricated high-gain amplifier module shows a high gain over 39.7 dB from 38 to 41 GHz. At 38.7 GHz, its maximum gain of 44.25 dB is achieved

LTCC-Based System-in-Package (SiP) Technology for Microwave System Integration

Monolithic low-temperature co-fired ceramic (LTCC) SiP modules have been presented for microwave applications. In order to integrate almost passive circuits of a radio system into the LTCC substrate, key technologies such as suppressing parasitic resonant modes, low-loss transitions and compact passive devices have been investigated. Well analyzed mechanisms on the parasitic resonant modes and their suppressing methods have been applied to high-isolation SiP structures. A strip line (SL) to CPW vertical transition using a stepped via structure embedding air cavities has been devised and has been used to design a SL BPF. A surface mount technology (SMT) pad transition has been developed by utilizing a modified coaxial line. A LPF composed of vertical plate capacitors and helical inductors and a 2 × 2 array antenna have been developed. A 61 GHz heterodyne transmitter LTCC SiP module has been implemented by monolithically embedding all passive circuits such as a SL BPF, 2 × 2 array antenna, SMT pads and feeding lines into it. A 60 GHz amplitude shift-keying (ASK) transceiver LTCC SiP module has been implemented as small as 17.8 × 17.9 × 0.6 mm3 by integrating a high-isolation via fence and a LPF. They have been characterized in terms of an output power, spectrum and link test