Equivalent circuit and analytical representation of double resonances in PCB striplines

Striplines present more than one resonance around frequencies at which multiples of half the wavelength of the propagated signals equal the spacing between fiber yarns along their path within a PCB. In this paper, a method to obtain the effective propagation constant and characteristic impedance considering this undesired effect is proposed. This allows the proper representation of striplines to assess the negative impact of the resonances in the performance of inter-layer interconnects on PCB. Data obtained using the new method shows excellent correlation with measurements up to 50 GHz. Furthermore, a methodology to implement the corresponding equivalent circuit of these interconnects is also shown, which allows to point out the simplicity and convenience of using the proposed method at microwave operation frequencies.