**4.3 Mechanical switch**

The following introduces a high-isolation SPDT SIW mechanical switch in V and W bands. Four via holes with the ring and cross are used in each SIW path to block the waves, as shown in **Figure 30**. A copper pad is put on top of the via holes. When a copper pad touches the SIW, via holes connect the copper pad and top layer copper. Via holes begin to block waves. When lifting the copper pad, via holes are invisible, and the switch is off-state. The proposed switch has a more than 50 dB isolation [38].

**Table 3** shows the performance parameter of the switches following different technological approaches.

**Figure 30.** *(a) Mechanical SPDT switch (b) schematic of the proposed SPDT.*


**Table 3.**

*Comparisons with different switches.*
