Diakoptics Modelling Applied to Flying Bird-Shape NGD Microstrip Circuit

This brief develops a diakoptics modelling of a flying bird topology constituted by interconnected piece-wises of admittance or Y-matrices. The diakoptics principle is established with passive system teared into several simplex elements as transmission and coupled lines (TLs and CLs). After introduction of subsystem Y-matrix, the global system Y- and S-matrices are established. To verify the model effectiveness, parametric analyses enabling to understand bandpass negative group delay (NGD) behavior of the flying bird topology. Furthermore, a microstrip circuit is designed, fabricated and tested. The modeled, simulated and measured NGD circuit responses are in excellent agreement. NGD value about -2.2 ns under transmission and reflection coefficients better than -2 dB and -13 dB is measured around 1.15 GHz.