ACCURATE CLOSED-FORM EXPRESSIONS FOR CHARACTERISTIC IMPEDANCE OF COUPLED-LINE WITH SLICED COAXIAL-CABLE

Based on a rigorous analysis of finite element and curve fitting techn iques, a set of accurate closed-form formulas are presented for the ev en and odd mode characteristic impedances of the coupled-lines made of two sliced coaxial cables. Compared with the rigorous solutions of th e impedances, the values from the general expressions give an accuracy of >1% for a wide-range of cut depths and are suitable for all couple d lines with cables whose outer-inner conductor diameter ratio is betw een 1.4 and 10. These formulas can be applied to industrial applicatio ns of coupled lines.