Miniaturized Microstrip Lowpass Filter with Ultra-Wide Stopband Performance Using Trapezoid Patch Resonators

A new miniaturized microstrip lowpass filter with ultra-wide stopband performance using trapezoid patch resonators is investigated. To achieve compact design and ultra-wide band rejection, trapezoid patch resonators are employed in the filter. To further reduce the circuit size of the filter, a meander transmission line is also introduced in the design. A demonstration filter with 3 dB cutoff frequency at 0.50 GHz has been designed, fabricated, and measured. Results indicate that the proposed filter is able to suppress the 26th harmonic response referred to a suppression degree of 15 dB. Furthermore, the proposed filter exhibits a small size of 0.122 lambda(g) x 0.109 lambda(g), where lambda(g) is the guided wavelength at 0.50 GHz.