Dual Stopband Type NGD Network Design for True Time-delay Based Multi-beam Steerer Application

An original application of stopband (SB) type negative group delay (NGD) electronic function is introduced.The unfamiliar SB-NGD circuit is designed with RLC-network lumped passive topology.The SB-NGD circuit is exploited to operate as a true-time delay (TTD) device for smart dualbeam phased array design.The two-port passive topology for designing an SB-NGD circuit constituted by an RLC-network is described.The theory and design method of the employed SB-NGD passive circuit are detailed.The microwave theory of the SB-NGD topology is elaborated from S-matrix modelling.The SB-NGD canonical form is innovatively introduced in function of the expected specifications.The synthesis design equations allowing to determine the R, L, and C component values in function of the NGD specifications are formulated.The SB-NGD behavior is verified by comparison of calculated and simulated S-parameters from two different proofs-of-concept (POC).Illustrative results with a very good agreement showing SB-NGD behavior are observed around the arbitrarily chosen central frequencies f 1 = 0.7 GHz and f 2 = 1 GHz over a bandwidth of 50 MHz.The design principle of TTD-based smart dual-beam is described.The dual-band SB-NGD circuit is designed to operate as a dual-band TTD device with fixed delays at t 1 (f 1 ) = 357 ps and t 2 (f 2 ) = 875 ps, respectively.A radiation pattern showing the smart dual-beam steering operating system at f 1 and f 2 frequencies is discussed.