A Review of True Time Delay-Based Beamforming and Analysis of Some Practical Implications

True time delay (TTD) elements have been explored over phase shifters in wideband beamforming applications to overcome the effect of beam-squint. This paper reviews different true time delay architectures reported in literature. The paper then discusses non-ideal effects of TTD circuits on beam- pattern of timed antenna array receivers. This helps in understanding the inevitable beam-squints associated with practical TTDs. The paper then discusses quantification of these non-idealities which would help in designing good variable delay lines for TTD based beamforming.