A highly miniaturized low-pass filter using microstrip open-loop and semi-hairpin resonators is designed and analyzed to enhance the bandwidth and further size reduction of this kind of elements. Initially, two microstrip open ring resonators and separately, two semi-hairpin resonators are arranged and attached back-to-back to each other respectively. A compact LPF is designed and simulated using these modified resonators. The size reduction of this proposed filter is reported about 65% with 190% enhancement of bandwidth in analogy with the conventional low-pass filters.
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