  A method is proposed to optimally design the Microstrip Nonuniform
Transmission Line (MNTLs) as lowpass filters. Some electrical and physical
restrictions are used to design MNTLs. To optimally design the MNTLs, their
strip width is expanded as truncated Fourier series, firstly. Then, the optimum
values of the coefficients of the series are obtained through an optimization
approach. The performance of the proposed structure is studied by design and
fabrication of two lowpass filters of cutoff frequency 2.0 GHz.
