Numerical Modeling and Analysis of a Cylindrical Reflector Antenna for Ground Penetrating Radar

Abstract -Since 1988, we have developed and commercialized various types of impulse ground penetrating radar (GPR) systems for locating buried structures and utility pipes. The performance of GPR systems depends mainly on the characteristics of radar antennas. In this paper, we propose a cylindrical reflector antenna fed by a resistively loaded Vshaped dipole as a new traveling wave antenna for GPR. We construct a numerical model of the antenna and analyze its characteristics using the method of moments based on RaoWilton-Glisson basis functions. The analysis results indicate that the new antenna's directivity is sharper and the ringing noise is less than in our commercialized GPR antennas, thus a weight saving can be achieved in the next GPR systems. Index Terms -Cylindrical reflector antenna, V-shaped dipole antenna, Ground penetrating radar

Modeling future wildlife habitat suitability: serious climate change impacts on the potential distribution of the Rock Ptarmigan Lagopus muta japonica in Japan’s northern Alps

Abstract Background The Rock Ptarmigan Lagopus muta japonica lives in the alpine zones of central Japan, which is the southern limit of the global distribution for this species. This species is highly dependent on alpine habitats, which are considered vulnerable to rapid climate change. This study aimed to assess the impact of climate change on potential L. muta japonica habitat based on predicted changes to alpine vegetation, to identify population vulnerability under future climatic conditions for conservation planning. We developed species distribution models, which considered the structure of the alpine ecosystem by incorporating spatial hierarchy on specific environmental factors to assess the potential habitats for L. muta japonica under current and future climates. We used 24 general circulation models (GCMs) for 2081–2100 as future climate conditions. Results The predicted potential habitat for L. muta japonica was similar to the actual distribution of the territories in the study area of Japan’s northern Alps (36.25–36.5°N, 137.5–137.7°E). Future potential habitat for L. muta japonica was projected to decrease to 0.4% of the current potential habitat in the median of occurrence probabilities under 24 GCMs, due to a decrease in alpine vegetation communities. Some potential habitats in the central and northwestern part of the study area were predicted to be sustained in the future, depending on the GCMs. Conclusions Our model results predicted that the potential habitats for L. muta japonica in Japan’s northern Alps, which provides core habitat for this subspecies, would be vulnerable by 2081–2100. Small sustainable habitats may serve as refugia, facilitating the survival of L. muta japonica populations under future climatic conditions. Impact assessment studies of the effect of climate change on L. muta japonica habitats at a nationwide scale are urgently required to establish effective conservation planning for this species, which includes identifying candidate areas for assisted migration as an adaptive strategy