• Journal of Satellite, Information and Communications
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• v.11 no.2
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• pp.69-73
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• 2016

In order to derive reliable propagation models for future millimeter-wave frequency indoor pico-cellular communications systems, accurate reflectivity data of building materials is necessary. The broad variety of building materials and construction codes makes accurate attenuation prediction very difficult without the support of specific construction data or measurements. This paper derives a transmission and reflection coefficient based on 13 GHz to 28 GHz measurement data. Transmission and reflection is measured by applying change in the reception angle of each building material, such as plasterboard. The transmission and reflection coefficient derived shows a correlation between frequency dependence and angle. As a result, as the reception angle is reduced, the reflected angle from the transmitter that could be received increases, showing that there is a correlation. In addition, the fundamental investigations carried out lay the foundation for radio channel-related research, which is essential for the development of future millimeter-wave communications systems.

• Journal of the Institute of Electronics Engineers of Korea TE
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• v.42 no.2
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• pp.23-28
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• 2005

This study was to suggest the propagation path loss and predictive model of propagation path analysis in order to apply the frequency in the millimeter-wave band to the real time inter-vehicle communication system. This study was to suppose the case of inter-vehicle communication on the one-way two-lanes road in the big cites with a lot of traffic jams in order to analyze the effect by the reflected wave of multipath. As a simulation of suggested model, it found out that the propagation path by the reflected wave was about 0.1[m]$\sim$5.1[m] longer than the one by the direct wave during the transmission of 100[m] wave direct path. Also, as a result of comparing the propagation path loss, the loss would be about -0.8[dB]$\sim$-4.2[dB] larger in case of wall reflection and -0.8[dB]$\sim$-1[dB] vehicle reflection. From the result above, this researcher found out that the path loss of reflected wave produced by the walls was about -3.2[dB] larger than the path loss produced by the adjacent vehicles.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.8
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• pp.1733-1739
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• 1997

An ultra-compact milimeter-wave broadband MMIC amplifier was designed using a direct-coupled topology combined with optimum feedback design. Significant reductionin the chip size was possible by employing the direct-coupled topology. Bias resistors required for the direct-coupled topology were also used as feedback elements. Feedback was optimized for millimeter-wave frequencies using reactive elements. The fabricated MMIC amplifier was realized in a chip size of 0.8mm$^{[-992]}$ and showed gains higher than 8 dB from 12 to 44 GHz. An output power of 30mW was achieved at 44 GHz with a drain efficiency of 10%.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.42 no.2
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• pp.323-330
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• 2017

The millimeter wave band is in the extremely high frequency band whose frequency and wavelength are 30-300GHz and 10-1mm respectively. When the obstacles block the propagation path which is not Line-of-Sight (LoS), due to a high propagation loss, it is hard to receive a signal in the millimeter wave band. Therefore When the path loss is measured in the millimeter wave band, the signal which is not distinguished from the noise is observed. Consequently, the path loss data which is limited in certain value is observed in the high propagation loss environment. If the original least square is implemented without taking the limitation of certain value into account, the path loss exponent may be underestimated. In this paper, the performance of Tobit Maximum Likelihood Estimation, Heckman Two-stage Model and Truncation Regression Model which can estimate properly in the censoring or truncated environments are compared.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.14 no.1
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• pp.161-167
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• 2014

This paper presents the results of permittivities of various materials by measurements of the dielectric properties for the materials in millimeter-wave band. Since the advantages of millimeter wave band include the miniaturization, weight reduction of component and a lot of information transfer, its study has received increasing attention of researches. Also, because of the characteristics of the band have the superior straightness and the small diffractive, in the band, the analysis for the reflection and transmission characteristics of the materials will be very important. Moreover, a low interference is one of characteristics of the band due to the fact that the millimeter wave is absorbed in the materials. Therefore, in this paper, the reflection and transmission characteristics of materials are measured in the band by using the free space method. Based on the presented result, the permittivities of the materials are derived by the calculation of Nicolson-Ross Weir method.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.6
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• pp.595-601
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• 2013

This paper presents an optimized design of a millimeter-wave on-chip dipole antenna using CMOS process. The serious flaw of the antenna using CMOS process is low radiation efficiency because of high permittivity and conductivity. To overcome the weakness, we need to widen radiation area in air and optimize distance between an antenna and a reflector. The radiation efficiency and bandwidth of the designed antenna are respectively 16.5 % and 22.3 % at 80 GHz. Systematic methods are attempt to analyze an effect on the antenna radiation efficiency. To widen radiation area in air, substrate cut angle and distance between the antenna and chip edge are adjusted. In addition, to optimize distance between an antenna and reflector, substrate thickness and distance between the antenna and a circuit ground plane are adjusted.

• ETRI Journal
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• v.36 no.3
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• pp.374-384
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• 2014

To achieve high-speed (giga-bit) connectivity for short-range wireless multimedia applications, the millimeter-wave (mmWave) wireless personal area networks with directional antennas are gaining increased interest. Due to the use of directional antennas and mmWave communications, the probability of non-interfering transmissions increases in a localized region. Network throughput can be increased immensely by the concurrent time allocation of non-interfering transmissions. The problem of finding optimum time allocation for concurrent transmissions is an NP-hard problem. In this paper, we propose two enhanced versions of previously proposed multi-hop concurrent transmission (MHCT) schemes. To increase network capacity, the proposed schemes efficiently make use of the free holes in the time-allocation map of the MHCT scheme; thus, making it more compact.

• Journal of electromagnetic engineering and science
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• v.1 no.1
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• pp.18-23
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• 2001

A fast-sweep broadband FM reflectometer system has been successfully developed and operacted at the DIII-D tokamak, producing reliable density Profiles with excellent spatial (1 $\leq$ cm) and temporal resolution (~100 $\mu$ s). The system uses a solid-state microwave oscillator and an active quadrupler, covering full Q-band frequencies (33~50 GHz) and providing relatively high output power (20~60 mW). The system hardware allows fu11band frequency sweep in 10 $\mu$ s, but due to digitization rate limit on DIII-D, sweep time was limited to 75~100 $\mu$ s. Fast frequency sweep has helped to reduce density fluctuation effects on the reflectometer phase measurements, thus improving reliability for individual sweeps. The fast-sweep system with high spatial and temporal resolution has allowed to measure fast-changing edge density profiles during plasma ELMS and L-H transitions, thus enabling fast-time sca1e physics studies.

• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2002.11a
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• pp.87-90
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• 2002

For the broad band wireless communications system, the composition of the millimeter wave system is needed. In other to commercialize that system, satisfaction of high frequency characteristic and low cost process is required. In this study, BPF which is very sensitive to the characteristic of fine line designed and fabricated using photoimageable thick film technology.

• Proceedings of the KIEE Conference
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• 2005.07c
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• pp.2383-2385
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• 2005

In this paper we discuss the design and fabrication of two millimeter wave filters, in bandpass and bandstop topologies for wireless communications applications. The filters are made using a high Q MMIC transmission line, which consists of a 100 micrometers tall, surface micromachined, air filled inverted microstrip structure on a quartz substrate, made by using a JSR THB-151N negative photoresist sacrificial layer mold and electroplating technology. The filter topologies include a new, very compact, four pole, cross-coupled filter, that presents a single transmission zero at the lower side of the passband, which provides a very sharp out of passband rejection at this region.