S-Shaped Conformal ArrayAs far as the S-shaped conformal array is concerned, once again the projection method proves to be an effective mean for pattern recovery. Figure 10 shows the absolute value of the co-polar component of the electric field jE / j of the S-shaped array without and with phase-compensation, normalized with respect to the peak value obtained through simulations for the corrected array: the co-polar component is shown, since the cross-polar one (i.e., jE h j) is well below 230 dB. First of all, as in the previous case it can be noticed that simulations and measurements from the realized prototype (represented in Fig. 11) agree. It can be seen that the main lobe direction changes from 08 to 98 with respect to the linear case, and that the side lobe level has consistently increased from 213.8 dB to 26 dB. The gain of the 1 3 4 undistorted linear array was 11:1 dB, when the array is deformed it becomes 10.5 dB in the new direction of maximum at h59 while it is only 8.2 dB for h50 (the original direction of maximum); after compensation the gain in the desired direction of maximum (i.e., h50 ) increases to 10.8 dB. Applying the projection method the radiation pattern can be recovered: the main lobe direction moves back to 08 and the side lobe level decreases to 211 dB. CONCLUSION

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As the usage of wireless technology grows, it demands more complex architectures and conformal geometries, making the manufacturing of radio frequency (RF) systems challenging and expensive. The incorporation of emerging alternative manufacturing technologies, like additive manufacturing (AM), could consequently be a unique and cost-effective solution for flexible RF and microwave circuits and devices. This work presents manufacturing methodologies of 3D-printed conformal microstrip antennas made of a commercially available conductive filament, Electrifi, as the conductive trace on a commercially available nonconductive filament, NinjaFlex, as the substrate using the fused filament fabrication (FFF) method of AM technology. Additionally, a complete high frequency characterization of the prototyped antenna was studied and presented here through a comparative analysis between full-wave simulation and measurements in a fully calibrated anechoic chamber. The prototyped antenna measures 65.55 × 55.55 × 1.2 mm3 in size and the measured results show that the 3D-printed Electrifi based patch antenna achieved very good impedance matching at a resonant frequency of 2.4 GHz and a maximum antenna gain of −2.78 dBi. Finally, conformality performances of the developed antenna were demonstrated by placing the antenna prototype on five different cylindrical curved surfaces for possible implementation in flexible electronics, smart communications, and radar applications.

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