A novel microstrip lowpass filter is proposed to achieve a very wide stopband and high selectivity as well as compact size. This filter utilizes a resonator with symmetric structure that consists of a transmission line, loaded with open stubs. Each stub ends with a defected taper and these tapers are coupled two by two to generate enhanced capacitances and increase the selectivity. Two units of these resonators are then used in combination with open stubs and triangular shaped resonators to widen the stopband and form the final filter. This filter is then fabricated and measured. The measured and simulated results are in good agreement.