**4.2 Magnetic control switch**

There are many attempts to magnetically control using ferrite loading. A way to load is shown in **Figure 28**, which consists of rectangular ferrite slabs loaded on the

**Figure 28.** *Ferrite-loaded SIW switch.*

**Figure 29.** *(a) The proposed SIW switch (b) simulated e-fields within the switch(off-state) [37].*

sidewall slots of SIW [36]. By applying external magnetic bias on the ferrite slabs, the cutoff frequency of the waveguide can be changed. The proposed switch has an IL of less than 1 dB and an isolation of 20 dB.

**Figure 29a** shows another magnetic control SIW switch with loading ferrite. A dc magnetic bias is applied to control the propagation capability. A Ferrite slab is placed on the surface of the SIW. The surfaces of the ferrite slab are covered with silver except for the one touching the substrate. As shown in **Figure 29b**, when the switch is off-state, e-fields present a strong transverse field displacement, causing the cutoff in TE10 mode. This way is easy to be handled by PCB technology and achieves better performance.
