A Comparative Analysis of Power Losses in Time-Modulated Arrays with Uniform, Non-Uniform and Optimized Time-Modulation

Suppression of unwanted harmonic radiation, known as sideband radiation (SR) is the major issue in time-modulated arrays (TMAs) as it leads to wastage of power and interferes with other communication systems operating at the same frequency. For optimized TMAs with uniform period of modulation (UPM),this sideband radiation is minimized by suppressing maximum sideband level (SBL) by optimizing the on-off time sequence of the antenna elements using evolutionary algorithms. However, recently it is investigated that SBL can be suppressed significantly for TMAs with non-uniform period of modulation (NUPM). In this paper, with the detail analysis of the power losses for TMA with UPM (TMA-UPM), TMA with NUPM (TMA-NUPM), it is shown that sideband suppression always may not lead to realize reduced harmonic power losses. Further it is observed that, power loss for optimized TMA (OTMA) is less as compared to both TMA-UPM and TMA-NUPM.