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An experimental study is described on the natural propagation of UHF band radio waves in straight subterranean galleries. An extensive measurement project took place in five underground localities and, based on the experimental data, an empirical model of radio wave transmission was derived. The model was calibrated according to the measurement data and compared with the theoretical waveguide approach to propagation prediction. The presented results can be used for the practical planning of wireless communications in speleology applications and as an experimental basis for further theoretical works. [ABSTRACT FROM AUTHOR]

Two dimensional microwave band gap structures have been constructed using lossy cylindrical glass samples (and). The power transmission spectra observed between 10 and 20 GHz for both square and triangular structures with three different lattice spacing (2.5, 1.4 and 0.9 cm) are explained in terms of the lattice spacing, filling fraction and loss tangent. The experimental results and the theoretical values agree well for the structures having higher filling fraction. Also, the values predicted from the scaling procedure agree well with the experimental values. The appearance of acceptor modes due to the introduction of defects in these structures is also reported. [ABSTRACT FROM AUTHOR]

At millimeter-waves, home furniture's and objects' dimensions can be equal or superior to the wavelength. A comparison between propagation measurements conducted within a residential house for two configurations, furnished and empty, underscores the influence of the furniture on millimeter-wave propagation. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 39: 230–233, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.11177 [ABSTRACT FROM AUTHOR]

For design of optimum microcells on a university campus, it is necessary to determine the propagation characteristics within a propagation environment represented by a relatively large open space scattered with large buildings and many trees. In this paper, for the radiated waves from seven PHS base sites at 1.9 GHz experimentally installed on the campus of Hokkaido University from 1993 to 1994, a median received signal level measurement method is proposed that can be applied in unpaved garden areas (with glass and pebbles) as well as in areas with woods, vegetation, and hilly terrain, and its effectiveness is discussed. Next, for quantitative evaluations of the increase of the propagation loss due to trees in the propagation paths on the campus, a propagation model is proposed that consists of the loss layer model and the geometrical optics two-ray model. In the loss layer model, the loss due to trees is replaced with a loss per unit length of the propagation path. The estimated median received signal level and the measured value are compared to determine the effectiveness of the model. The increase of the propagation loss on the campus due to trees can be estimated if the loss per unit length of the tree layer by the present loss layer model is chosen to be about 0.1 dB/m for the base site antenna installed on the rooftop of the building and 0.07 to 0.09 dB/m for the antenna installed on the roof of the public phone box. © 2001 Scripta Technica, Electron Comm Jpn Pt 1, 84(8): 49–61, 2001 [ABSTRACT FROM AUTHOR]

A calibration scheme is presented for synthesizer phase fluctuations in virtual antenna array measurements for wideband mobile radio channel sounding. The standard deviation of the direction-of-arrival error is calculated from the Allan variance of frequency synthesizers. Estimated errors for a 5.3 GHz channel sounder are less than 1°. © 2000 John Wiley & Sons, Inc. Microwave Opt Technol Lett 26: 183–187, 2000. [ABSTRACT FROM AUTHOR]

In this correspondence, we first classify confined spaces, and then present some experimental data on the natural propagation radio signals. The effects of traffic in confined spaces on natural propagation are studied in terms of the additional loss. It is shown that the propagation losses due to confined spaces themselves are within several decibels per hundred meters, while the additional losses due to traffic could be very large. For instance, the additional loss at 900 MHz in two-lane road tunnels reaches 50 dB at 95% probability margin for the traffic density of 150 heavy trucks per hour. The measured additional loss is added to the existing model for more accurate path loss prediction. ©1999 John Wiley & Sons, Inc. Microwave Opt Technol Lett 23: 38–42, 1999. [ABSTRACT FROM AUTHOR]

Normal incidence broadband transmission measurements across different building materials have been made in the 5.8 GHz frequency band, and transmission coefficients have been computed. Several samples of each material have been measured, showing that a single sample is not enough to obtain a good characterization, and confidence bands are needed. ©1999 John Wiley & Sons, Inc. Microwave Opt Technol Lett 23: 7–12, 1999. [ABSTRACT FROM AUTHOR]

The attenuation due to rainfall in tropical regions has generated more concern in recent years. In Singapore, a microwave propagation experiment of line-of-sight communication has been conducted, and some experimental results have been obtained. The specific rainfall attenuation and rain attenuation duration temporal cumulative distributions over a ten-month period for 15 and 38.6 GHz are analyzed in this paper. The frequency scaling relationship between distributions is also discussed in detail. The results obtained in Singapore's tropical environment are found to be quite different from the CCIR's predictions. The results of our experiment can be employed to guide the design and application of terrestrial microwave communication systems, especially in tropical regions. ©1999 John Wiley & Sons, Inc. Microwave Opt Technol Lett 21: 470–473, 1999. [ABSTRACT FROM AUTHOR]

The fundamental leaky wave propagating in a microstrip array on a dielectric substrate is investigated with a concept of constructive interference. The advantages of the proposed technique over other more rigorous methods are its simplicity and physical insight. Based on such simple analysis, an experimental procedure is introduced for the verification of the existence of the fundamental leaky wave in a microstrip array structure. ©1999 John Wiley & Sons, Inc. Microwave Opt Technol Lett 20: 261–265, 1999. [ABSTRACT FROM AUTHOR]

Continuous current spectrum of an integrated open waveguide structure is identified as the branch cut contribution to singularity expansion of those currents in the complex axial transform plane. Those singularities in that plane include poles associated with the guiding structure and branch points contributed by layered background environments. The manner in which singularities in background environments manifest themselves as branch points in the complex axial transform plane is reviewed. Based on spectral integral equation formulation, approximate and analytical expression for spatial microstrip current is obtained. That approximation is based on Maxwellian distribution for the transverse current profile. This result is the representation of currents in terms of proper propagation mode spectrum. During the integration around branch cuts, singularities in the transverse transform plane migrate in a complicated manner. The trajectories of this migration are identified and suitably accommodated during the real axis integration in that plane. This overall procedure leads to a decomposition of the total currents into bound modes and continuous spectrum contributions. This representation is validated by real axis integration in the axial transform plane. The quasi TEM characteristic impedance of bound mode is calculated and validated by comparison with well-known empirical formula. [ABSTRACT FROM AUTHOR]