Harmonic Beamforming Based on Modified Single-Sideband Time Modulated Phased Array and Its Enhanced Version

Recently, harmonic beamforming in the time-modulated array (TMA) has attracted much attention. In this study, two kinds of beamforming systems of TMA based on the single-sideband time-modulated phased array (STMPA) and enhanced STMPA are presented, and the +1 st harmonic beamforming is performed. Based on the basic structure of STMPA and ESTMPA, we transform the design of the I/Q modulator, then the modified STMPA (MSTMPA) and modified ESTMPA (MESTMPA) are presented. The two channels in an I/Q modulator are each connected to an antenna with other structures keep constant. Hence, the number of antennas can be multiplied, and the system complexity can be reduced with an increase in the number of antennas especially for large-scale applications. In addition, the array aperture is enlarged with the same number of I/Q modulators, and the performance of the beam pattern is improved. However, without the single sideband structure, the ( $4k-1\cap 3k)^{\mathrm {st}}$ and ( $8k-1$ ) st harmonics in STMPA and ESTMPA cannot be eliminated; therefore, the bandpass filter is used at the output of the system; thus, the +1 st harmonic can be extracted. The derivations and analysis are given in detail, and STMPA and ESTMPA compared. Finally, the effectiveness of the proposed systems is verified by simulation results and the +1 st harmonic can be formed in desired directions.