Miniaturisation and harmonic suppression method of parallel coupled-line filters using lumped capacitors and grounding

A new miniaturisation and harmonic suppression method of the parallel coupled-line filter using lumped capacitors and grounding is proposed. The method can dramatically reduce the size of the resonators in the parallel coupled-line filter. In addition to size reduction, an excellent suppression of spurious harmonic responses, which are inherent in this type of filter, is achieved with improved skirt characteristics.