**3.3 Ultra-wideband and wideband isolation PD**

Another filtering method is to load the slot line. As shown in **Figure 24**, two-slot lines are loaded on the SIW to get a third-order filtering response [30]. The isolation network consisting of the coplanar waveguide feeding line of Port 1, the interdigital capacitor, and the resistor is embedded in SIW, which expands the bandwidth of

**Figure 24.** *Proposed SIW FPD [30].*


#### **Table 2.**

*Comparisons with different power dividers.*

isolation and achieves lower insertion loss and good isolation. The proposed SIW FPD has isolation higher than 21 dB from 5.59 to 6.4 GHz.

**Table 2** shows the performance parameter of the power dividers following different technological approaches.
