**4.3. Experimental verification**

312 Ultra Wideband – Current Status and Future Trends

(c) two-SLTR and (d) two-SSIR

**Figure 20.** Photographs of fabricated UWB-filters for notched band: (a) single-SLTR, (b) two-SLTR,

(a) (b)

(c) (d)

(a) (b)

**Figure 21.** Comparisons of measured and simulated responses of the filters: (a) single-SLTR,

(c) (d)

(b) single-SLTR with three slots, (c) two-SLTR, (d) two –SSIR

Fig. 20 shows the photograph of the fabricated SLTR and SSIR filters for notched band. Fig. 21 shows a comparison of measured and simulated responses of the SLTR and SSIR filters with a notched band. The measured and simulated results have shown good agreement with a notch is capable of narrowing notched band, having good insertion losses within the passband and also widening the upper stopband. The measured return and insertion losses are found to be lower than 10 dB and higher than 2 dB, respectively over desired UWBpassband. The notched frequency of about 5.6 GHz has a bandwidth of about 276 MHz. The proposed filters show narrow notched band and improved upper stopband performance with high insertion loss. The upper stopband with the insertion loss lower than 10 dB occupies an enlarged range of 14 to 18 GHz. The group delay of both filters slightly varies between 0.2 to 0.3 ns in the passband. These superior stopband performances are caused by the stopband characteristics of the proposed slotted resonator structure, and narrow notched band is caused by embedded fold-slot structure.
