Miniaturised wide stopband rejected microstrip filter with coupled spur-lines

The miniaturised wide stopband rejected microstrip filter is proposed. In order to cause the wide stopband suppression, coupled spur-lines are taken into consideration for the newly proposed bandpass filter. The coupled spur-lines can provide an attenuation pole at the second harmonic to enhance the suppression and broaden the stopband. Design methods are also introduced, and the measurement of the fabricated example is presented for validating the filter configuration.