**4. Fabrication techniques**

**Figure 10** shows the fabrication process for the NWSIW. As explained in Section 2, this technology differs from classical SIW since it takes advantage of the porous AAO template for creating by electrodeposition metallic nanowires inside the pores in order to form equivalent metallic shielding walls as explained in sections 3.1 and 3.2.

#### **Figure 9.**

*Performances of tapered transition of Figure 8 as a function of taper length (left) and taper width (right). Top row: S11, bottom row: S21. Simulations are made for W = 6 mm and P = 50%.*

The first step is the deposition of a metallic layer (blue color) by electroplating on the back side of the AAO template, step 1 in **Figure 10**; this layer is used as cathode during the electrodeposition process.

Then in step 2 the areas where electrodeposition of NW is needed are defined; equivalently the areas where electrodeposition is unwanted are determined. As detailed in [19–21] two options are possible, named A and B. In option A, a metal layer is electroplated on top of AAO. Openings are created by laser etching this top metal layer in areas where electrodeposition of MNW is desired, to allow the penetration of the electrolytic solution inside pores that are not covered by the metal. Option B is dual/opposite; the areas where MNW are unwanted are selected by laser burning locally the surface of the AAO in order to destroy locally the porosity and clog the pores, making electrodeposition of MNWimpossible in these areas. The burned surface of AAO is represented as a magenta layer in **Figure 3B**. It remains present during step 3 to 5. The result of step 2 for both option A and B is step 3, where only open pores are available for electrodeposition. The result of step 2 for both option A and B is step 3, where only open pores are available for electrodeposition.

The last 2 steps are similar for option A and B. In step 4, electrodeposition process described in [21] is used to grow MNW in free pores in such a way that pores are slightly overfilled. By doing so, during step 5 when electroplating of top *Challenges and Perspectives for SIW Hybrid Structures Combining Nanowires and Porous… DOI: http://dx.doi.org/10.5772/intechopen.105148*

**Figure 10.**

*Steps of fabrication process for the NWSIW.*

metal layer occurs, good electrical contacts are created between top metal layer and upper end of MNW, forming efficient metallic shielding walls for the equivalent waveguide.
