Wide Band Antenna with Ultra-smooth Spectral Characteristics

摘要

Understanding the evolution of Universe is, inthe forefront of, the modern day observational cosmology. Itrequires precise and accurate measurement of cosmologicalsignal, orders of magnitude weaker than the bright skybackground. Detection of such a signal having distinct spectralsignature, needs an antenna with frequency independentcharacteristics over more than an octave bandwidth. Aspherical monopole antenna has been designed to operate inthe frequency range 50-200 MHz with a spectral smoothness ofabout few parts in 104. The structure has been modeled andoptimized using WIPL-D, to minimize spectral features arisingout of abrupt reflections of surface currents and frequencydependent radiation patterns. A prototype has been built tovalidate the design. This paper presents the methodologyadopted in the overall antenna design, experiences in itsprototyping and simulation and the measurement results.