This paper presents a 120-GHz-band amplifier module with a hermetic sealing structure for a broadband wireless system. The sealing structure for F-band waveguides is a laminate composed of two sealing plates and a spacer. Each sealing plate has a fused glass window and separates inside air from the ambient atmosphere. The design process of the sealing structure is simple and has good simulation fidelity. The hermetic sealing structure designed for an amplifier in a 120-GHz-band wireless link has an insertion loss of less than 1dB and a return loss of more than 15dB in the operating band. We made three kinds of sealed modules to evaluate the sealing function. The modules sealed with this technique meet the hermetic-seal standard in MIL-STD-883F. We then verified that the sealing structure on the sealed modules has a small enough effect for the transmittance of the intrinsic characteristics. In addition, we performed 10-Gbit/s data transmission using a sealed amplifier module with the bit error rate of less than 10-10.

A compact 120-GHz-band finline orthomode transducer (OMT) with high isolation between orthogonal ports (Iop) was designed and fabricated for bidirectional wireless data transmission with polarization multiplexing. To achieve high Iop, finline OMTs normally use a resistive card to decrease unwanted resonance, that occurs on the finline, but adding a resistive card complicates the fabrication process and raises the cost of fabrication. Our proposed finline OMT uses an improved finline design in which the resonance frequency is controlled in order to expel unwanted resonance from the operation bandwidth of the 120-GHz-band wireless link. The proposed finline design enables high Iop without using a resistive card, which simplifies the fabrication process and lowers the cost of fabrication. A square horn antenna, which is attached to the finline OMT, is also designed to suppress unwanted polarization rotation of reflected waves, which further improves Iop. The proposed finline OMT has a transmission loss of less than 1.2dB, return loss of more than 12dB, cross polarization discrimination of more than 30dB, and Iop of more than 50dB across the entire occupied bandwidth of the 120-GHz-band wireless link. These characteristics are sufficient not only for 10-Gbit/s bidirectional data transmission but also for 20-Gbit/s unidirectional 2-ch data transmission by polarization-multiplexing.

This paper presents 10-Gbit/s bidirectional and 20-Gbit/s unidirectional wireless data transmission systems using 120-GHz-band finline orthomode transducers (OMTs). A new finline OMT was fabricated with two improved designs, to adapt it to the data transmission characteristics of the 120-GHz-band wireless link. One improvement is higher isolation between orthogonal ports and the other is lower group delay variation. The measured isolation is more than 59dB at the carrier frequency of the 120-GHz-band wireless link, and the measured group delay variation is 43ps. Using the finline OMT, we developed 10-Gbit/s bidirectional and 20-Gbit/s unidirectional wireless equipment that can transmit two channels of 10-Gbit/s data using polarization multiplexing. With this wireless equipment, we succeeded in 10-Gbit/s bidirectional and 20-Gbit/s unidirectional wireless data transmission, which leads to successful seamless connection to 10 Gigabit Ethernet and 12-ch high definition television signal transmission.

This paper investigates space and polarization multiplexing for multichannel transmission in a 120-GHz band wireless link system. The 120-GHz-band wireless equipment employs Cassegrain antennas with a gain of about 49dBi and cross-polar discrimination of 23dB. When each of two 120-GHz wireless links transmits a 10-Gbit/s data signal in the same direction over a distance of 800m, a bit error rate (BER) of below 10-12 is obtained when the receivers are set 30m apart. When forward error correction and polarization multiplexing are used for each wireless link, we can set two wireless links within 1m of each other and obtain a BER below 10-12. Moreover, we have experimentally shown that the rain attenuation of V- and H-polarization 120-GHz-band signal is almost the same.

Superconducting Transition edge sensor (TES) coupled with a heavy metal absorber is a promising microcalorimeter for Gamma-ray (γ-ray) spectroscopy with ultra-high energy resolution and high detection efficiency. It is very useful for the non-destructed inspection of the nuclide materials. High resolving power of γ-ray peaks can precisely identify multiple nuclides such as Plutonium (Pu) and Actinides with high efficiency and safety. For this purpose, we have developed the TES coupled with a tin absorber. We suggest the new device structure using the gold bump post which connects a tin absorber to the thermometer of the superconducting Ir/Au bilayer. High thermal conductivity of the gold bump post realized strong thermal coupling between the thermometer and the γ-ray absorber, and it brought the benefit of large pulse height and fast decay time. Our TES achieved the good energy resolution of 84 eV FWHM at 59.5 keV. Using this TES device, we also succeeded to demonstrate the nuclear material measurements. In the measurement of a Pu sample, we detected the sharp γ-ray peaks from 239Pu and 240Pu, and of a Fission Products (FP) sample, we observed fluorescence X-ray peaks emitted by the elements contained in FP. The TES could resolve the fine structures of each fluorescence X-ray line like Kα1 and Kα2. In addition to that, we developed the TES coupled with tantalum absorber, which is expected to have higher absorption efficiency for γ-rays. This device reported the best energy resolution of 465 eV at 662 keV.

Many researchers have recently studied various applications such as Inter-Vehicle Communications (IVC) and Road-to-Vehicle Communications (RVC) for Intelligent Transport Systems (ITS). RVC is a key technology that can connect vehicles with the internet through Road Side Units (RSUs). Relative positions between vehicles vary within short periods of time. Neighboring vehicles and barriers cause shadowing that blocks communication for extended periods of time between RSUs and vehicles. We propose a fast scheme of Mobile IPv6 handover using dual-band communications in RVC. This scheme uses ISM and UHF dual bands. It switches to the UHF band during handover or in the shadowing period. We demonstrate that the proposed scheme can establish continuous communications through computer simulations.