Direction Finding Using a Single Antenna With Blade Modulation

Abstract

A single top-hat antenna using blade modulation is presented for direction finding (DF). Unlike conventional DF techniques requiring an antenna array with multiple elements, the fixed single antenna is utilized to receive incoming signals. To enhance radiation pattern diversity and perform direction of arrival estimation, four rotating blades are placed around four corners of the antenna. The antenna is designed to operate at the frequency where the incoming wave is in resonance with the metallic blades. The incoming signals are recorded as blades rotating with an angle from 0 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^\circ $</tex-math></inline-formula> to 180 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^\circ $</tex-math></inline-formula> . To validate the radiation pattern diversity at the resonant frequency and out of the operational frequency band, correlation coefficients of amplitude and phase of complex radiation patterns between the antennas with different blade rotation angles are investigated. DF accuracy in azimuth directions of the proposed single antenna with blade modulation is demonstrated by Cramer–Rao bound using the complex radiation patterns at different frequencies.