Katsumi Fujii

Development of Complex Relative Permittivity Measurement System Based on Free-Space in 220–330-GHz Range

For measuring complex relative permittivity of more than 300 GHz in the THz region, time-domain spectroscopy (TDS) is usually used. On the other hand, a free-space method using a vector network analyzer (VNA) is used below 300 GHz. However, these methods have not been compared and continuity of complex relative permittivity measurement around 300 GHz has not been evaluated. We developed a system for measuring complex relative permittivity that can be operated at 220-330 GHz. This system is based on the free-space method. We compared the complex relative permittivity using a VNA and by TDS to evaluate our system and the continuity of complex relative permittivity measurement in the frequency domain. We first compared relative permittivity and dielectric loss between both methods. We then evaluated the measurement uncertainty in consideration of the thickness of materials under test (MUT), time span of the time-domain gating, linearity, stability, aperture alignment, and measurement repeatability. The dispersion in MUT thickness measurement was found to be the dominant source of uncertainty in measuring complex relative permittivity measurement. The maximum difference in relative permittivity and dielectric loss between both methods was less than 0.22 and 0.17 when MUT E was measured. For the measurement result with expanded uncertainty, the relative permittivity of VNA was 3.92±0.44 and that of TDS was 3.70±0.16, the dielectric loss of VNA was 0.30±0.52 and that of TDS was 0.13±0.02, respectively. The measured complex relative permittivity by using the VNA and by TDS were observed within the expanded uncertainty. We verified the availability of the measured complex relative permittivity by using our measurement system and the continuity of complex relative permittivity measurement at 300-GHz band.

Demonstration of 20-Gbps wireless data transmission at 300 GHz for KIOSK instant data downloading applications with InP MMICs

We present 20-Gbps wireless ASK data transmission at 300 GHz with an all-electronic transmitter and receiver for KIOSK instant data downloading applications. The transmitter and receiver MMICs are based on 70-nm indium-phosphide-based high electron mobility transistor technologies of which the cut-off frequency (fmax) is approximately 700 GHz. For an experiment, the transmitter and receiver were packaged in a split-block waveguide and dedicated metallic housing, respectively. With 30-dBi and 25-dBi horn antennas for the transmitter and receiver, error free data transmission (bit error rate <; 1 × 10-9) was achieved up to 80-cm link distance.

A novel standard loop antenna for antenna calibration in the MF and HF bands

Measuring loop antennas used in the frequency band below 30 MHz have been generally calibrated with the standard field method, where a standard loop antenna generates a well-defined magnetic field at an antenna under calibration. However, it is very difficult to evaluate the strength of the generated field with great accuracy. To cope with this problem, the present paper newly develops a calculable loop antenna consisting of a loop element and a 180 degrees hybrid junction. This antenna can be used as a standard transmit antenna as well as a standard receive antenna. Thus, it is applicable to other calibration methods, such as standard antenna method and three-antenna method, which can improve the accuracy of the antenna calibration. As an example, a calibration system is proposed for the standard field method, where the proposed calculable antenna is used as a standard transmit antenna. The strength of the generated field is rigorously evaluated by measurements of the reflection coefficient and the supplied power at the transmit antenna input. From experimental measurements using the proposed calibration system, it is ensured that the proposed system can provide antenna calibration with accuracy within 0.3 dB in almost all the frequency range from 1 to 30 MHz

Standards Research in Japan: Latest Development of Millimeter-Wave and Submillimeter-Wave Measurements

In recent communication networks, 100 Gb/s passive optical Ethernet networks have been established and started becoming widely used. In consumer broadcasting, the use of high-definition television in studio and live-relay broadcasts has been planned by the Japanese government. These high-speed wireless technologies require the millimeter-wave frequency band from 30 to 300 GHz to provide sufficient bandwidth. In a wireless link system, spurious signals must be identified and managed in accordance with Japanese Radio Law relating to the recommendations by the International Telecommunication Union Radio section (ITUR). According to the regulations for spurious domain emission in ITU-R SM 329-10 (02/2003), limits on spurious domain emissions for radio equipment over the range of 9 kHz to 300 GHz must be currently considered and tested before being applied. The recommended frequency ranges of spurious domain measurement depend on the fundamental frequency in the wireless link system.

Measurement of complex permittivity of insulating materials for THz telecommunication modules

Measurement methods of complex permittivity of dielectric materials from 20 GHz to 3 THz are introduced. The dielectric properties of a liquid crystal polymer were not affected by environmental conditions, thus liquid crystal can become a candidate for insulating materials used in THz communications.

Equivalent capacitance substitution method for monopole antenna calibration

The International Special Committee on Radio Interference (CISPR) has included in the draft standard CISPR 16-1-6, the equivalent capacitance substitution method (ECSM) for the calibration of monopole antennas below 30 MHz. To provide background information on the ECSM for CISPR 16-1-6 currently discussed, the present paper investigates the principle and uncertainty analysis of the ECSM in detail.

20-Gbit/s ASK wireless system in 300-GHz-band and front-ends with InP MMICs

We present a 20-Gbit/s ASK wireless system in the 300-GHz band for kiosk data downloading. The front-ends (transmitter and receiver) are manufactured by using InP-based monolithic microwave integrated circuits with high electron mobility transistors. We successfully demonstrate 20-Gbit/s data transmission using these front-ends at link distances from 50 cm to 1 m. The measured bit error rate is less than 10-6 up to the distance of 1 m.

Uncertainty analysis for three antenna method and standard antenna method

CISPR SC-A has investigated EMC antenna calibration for many years to establish a new standard, CISPR-16-1-6, specifying calibration methods and providing appropriate procedures for uncertainty evaluation. This paper gives the essential ideas required for the uncertainty evaluation.

Impact of electromagnetic noises from PCs on the performance of MB-OFDM UWB systems

The impact of electromagnetic noises from a PC on the bit error rate (BER) performance of a multiband orthogonal frequency division multiplexing (MB-OFDM) ultra wideband (UWB) communication system equipped on the PC is analyzed. The results of numerical simulation indicate that the PC noise consisting of the harmonic components of the PC clock causes considerable bit error rate (BER) degradation in the UWB system particularly those systems operated in high data-rate communication modes. It is also found that the frequency modulation of a PC clock signal, the so-called spread spectrum clocking (SSC), has no effect on mitigating BER degradation, although SSC techniques are commonly used in PCs for reducing the power spectral density of radiated noise. An interference mitigation scheme using Viterbi decoding with channel state information (CSI) is proposed on the basis of a novel receiver structure in which a reference PC clock signal is fed into the UWB receiver by the PC in order to accurately estimate the instantaneous frequency of interfering clock harmonics.

New Connecting Structure for Waveguides with Special Connectors

This paper introduces new connecting structure for waveguides. The structure, similar to that of the SMA connector shell, especially shows its advantages for high-frequency and small waveguides. Compared to conventional waveguide connecting structures such as flanges, the proposed structure is easier to connect/disconnect and does not occupy spaces. Additionally, authors clarify that the connection performance of the proposed structure is almost the same as the conventional connecting structure.