An Interpolation-Based Time-Modulated Antenna Array for Beam Scanning at Carrier Frequency

Abstract

The formula of the Fourier series for a periodic function indicates that traditional periodic time modulation only provides amplitude weighting at the carrier frequency of a time-modulated array (TMA). Therefore, beam scanning through time modulation technique could only be realized at harmonic frequencies. In order to achieve low sideband levels (SBLs) in harmonic beam scanning, a large number of modulation statuses are required in TMAs, which significantly increases the cost and complexity of the entire system. The intent of this work is to develop a novel TMA with array-interpolation aperture and ON–OFF time modulation to achieve beam scanning at the carrier frequency. By performing interpolation computation at the antenna array level, high-precision beam scanning with low SBLs can be realized with pseudorandom ON–OFF time modulation and a static 1-bit phase control. As compared with the state-of-the-art designs, the proposed TMA requires much fewer modulation statuses, and it significantly facilitates beam-scanning control. A forward design strategy is presented to analytically determine the time modulation sequences and the static 1-bit phase statuses for specified beam scanning angles and sidelobe levels (SLLs). Numerical and experimental results well demonstrate the effectiveness of the proposed TMA.