  We demonstrate significantly improved performance of a microwave true time
delay line (TTDL) based on an integrated micro-ring resonator (MRR) Kerr
optical comb source with a channel spacing of 49GHz, corresponding to 81
channels over the C-band. The broadband microcomb, with a record low free
spectral range of 49GHz, results in a large number of comb lines for the TTDL,
greatly reducing the size, cost, and complexity of the system. The large
channel count results in a high angular resolution and wide beam steering
tunable range of the phased array antenna (PAA). The enhancement of PAA
performance matches well with theory, corroborating the feasibility of our
approach as a competitive solution towards implementing compact low-cost TTDL
in radar and communications systems.
