**5. Conclusion**

In this chapter, the novel SLTR and SSIR UWB-bandpass filters with improved upper stopband performances have been presented and implemented. By properly forming SLTR and SSIR together with two interdigital coupled lines at both ends, the proposed filters are designed and constructed. The single-SLTR and SSIR filters show their performances in suppression of spurious responses. Also, two-SLTR and two-SSIR filters are designed and fabricated to show that they improve the passband and upper stopband performances with sharpened rejection skirts outside the passband and widened upper stopband. When comparing with SLTRs, we find that the SSIR structures are easier to design and fabricate and they also have better stopband characteristics. In addition, the SLTR and SSIR filters using embedded slot and embedded fold-slot with notched band, reduce size and improved upper stopband performances have been presented and implemented. The proposed filters demonstrate their capability in narrow notched band with the embedded slot, embedded fold-slot feed and suppression of spurious responses with slotted resonators. Also, the fabricated filters prove that they can create notched band and improve upper stopband performances with sharpened rejection and widen the upper stopbands.
