Multilayer Radome Design And Experimental Characterization Of Scattering and Propagation Properties for Atmospheric Radar Applications

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Wednesday, 7 January 2015
Phoenix Convention Center - West and North Buildings
Jose Diaz, NCAR, Boulder, CO; and J. L. Salazar-Cerreno, A. Mancini, and J. G. Colom
Manuscript (2.7 MB)

Handout (37.0 MB)

In general, any radome should provide electromagnetic transparency and structural strength to protect the antenna. Electromagnetic transparency consists of low reflections, low transmission loss, and minimum distortion of polarization-dependent antenna patterns. Structural strength is related to wind loading, stability, and integrity for mitigating environmental conditions such as temperature, humidity, and pressure. For operational systems, the radome is the essential component since it minimizes the high wind load, reduces the need for a heavy and expensive pedestal, and provides consistent nominal temperatures that facilitate the operation and maintenance and improves the life cycle cost of the system. One adverse effect of the radome is the performance degradation of radio signals when they operate in the presence of water or ice. Water accumulated on the radome surface can significantly affect the radar signal. Depending on the frequency of operation, rain and wind conditions, shape, and material, a radome can significantly attenuate, reflect, and depolarize the radar or communication signals.

A novel analytical method for evaluating the electrical performance of a flat tilted radome for a dual-polarized radar antenna under rain conditions was proposed by the (J. Salazar, V. Chandrasekar et al. 2013). Attenuation, reflections, and induced cross-polarization were evaluated for different rainfall conditions and radome types. The authors presented a model for estimating the drop distribution on a radome surface based on skin surface material, area, inclination, and rainfall rate. Then a multilayer radome model based on the transmission line equivalent circuit model is used to characterize the radome's scattering parameters. Numerical results were compared with radar data obtained in NEXRAD and CASA systems and good agreement is found.

The purpose of this paper is to present a new experimental approach to accurately characterize the scattering and propagation properties of multilayer radome under artificial rain conditions. The main goals are: 1) Present the development of a unique and automated radome station test. 2) Characterize the effective dielectric constant, tangent loss, attenuation, reflections, and induced cross-polarization for a multilayer sandwich radome for X-band under the influence of controlled artificial rain, and 3) Use the measured results to validate the analytical model proposed for estimating the drop distribution on a radome surface based on skin surface material, and area, inclination.