**4. Conclusions**

**Figure 30.** Normalized radiation pattern of the conformed-profile horn at frequency 12.5 GHz in (a) E-plane and (b) H-plane.

120 Emerging Microwave Technologies in Industrial, Agricultural, Medical and Food Processing

**Figure 31.** Pyramidal horn gain over broadband compared with simulation and commercial horn antenna from Flann.

Although benefits of additive manufacturing are well known to the engineer community, its real application to a particular field needs a detailed analysis, even more when considering a low-cost perspective. With the work presented throughout this chapter, it can be concluded that low-cost 3D printing presents great advantages for the microwave engineer. The promptness to print models of great quality or to implement traditionally unfeasible geometries may be used for two main applications: prototyping and manufacturing of functional devices. Both applications may also increase the quality of microwave engineering education, especially for institutions without extraordinary resources.

In order to successfully address a low-cost 3D printing process in the microwave field, it is necessary to first take into account several key aspects: to set the maximum achievable working frequency, the best way to perform a metallization process, and the most suitable structure segmentation. This work has described all of them, emphasizing the best solutions as per authors' knowledge.

In addition, several prototypes of state-of-the art designs have been presented, together with real passive waveguide devices—individual filters, a diplexer, and a branch-line coupler—and two horn antennas. Experimental results have been discussed to evaluate their use in real-world applications. In general terms, the results agree quite well with the expected response, yet the discrepancies have also been explained.

In summary, additive manufacturing, and, in particular, its low-cost version, has a very promising future in the engineering field. Although further research is required—for instance, to enhance conductivity—it is a powerful tool worth to be discovered.

[7] Saracho-Pantoja IO, Montejo-Garai JR, Ruiz-Cruz JA, Rebollar JM. Low-cost additive manufacturing: A new approach to microwave waveguide engineering education through 3D printing. International Journal of Engineering Education. 2017;**33**(2(A)):741-750

Additive Manufacturing of 3D Printed Microwave Passive Components

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