# A Photonically-Excited Leaky-Wave Antenna Array at E-Band for 1-D Beam Steering
## 6 Discussion  
In this manuscript, we reported the premier work on the design, photonic integration, and characterization of a leaky-wave antenna array in PCB technology at E-band frequencies. The designed antenna exhibits beam steering with frequency and a scalable layout. Measurements of the radiation pattern are performed on a two-row array, adapted for probe excitation. A 22\({}^{\circ}\) scan range, including broadside, is shown across the frequency of operation of the antenna (75 GHz to 85 GHz), which is in agreement with full-wave simulations. Measurements of return losses are also in good agreement with simulations. In this respect, a method to de-embed the probe plus interconnection is described in the appendix. To the best of our knowledge, this is one of the few realizations of periodic 1-D structures in which the complete periodic structure shows adequate matching characteristics (\(S_{11}\) < -12 dB) at broadside. This is due to increased losses per period, which also helps to obtain a compact structure and higher radiation efficiency, and to enlarge the scanning range of the antenna from the backward quadrant to broadside and the forward quadrant. Furthermore, the antenna is tested in a wireless communications system, demonstrating error-free transmission at 2.15 Gbps and a 25 cm link distance. Finally, the application of the LWA antenna as a simple means to align mm-wave LoS links was outlined.  
Conceptualization, A.J.P.-G., R.S., L.E.G.-M., and D.G.-O.; methodology, A.J.P.-G., M.A., and G.C.D.B.; formal analysis, A.J.P.-G.; investigation, A.J.P.-G., M.A., G.C.D.B., L.B., and F.F.; writing--original draft preparation, A.J.P.-G.; writing--review and editing, L.E.G.-M., R.S., and D.G.-O.; supervision, G.C.D.B., R.S., L.E.G.-M., and [PERSON]-O.; funding acquisition, G.C.D.B., R.S., L.E.G.-M., and [PERSON]-O. All authors have read and agreed to the published version of the manuscript.  
Figure 11: (**a**) Hybrid interconnections in a data center; the continuous yellow lines represent wired fiber links whereas the dashed red lines illustrate reconfigurable wireless LoS links. (**b**) LWA set-up, co-located with the wireless transceivers, to enable alignment in a LoS link.  
**Funding:** A.J.P.-G., [PERSON]-O., and R.S. acknowledge funding by Labex CominLabs and by the European Union through the European Regional Development Fund (ERDF), and the French region of Brittany, Ministry of Higher Education and Research, Rennes Metropole and Conseil Departemental 35, through the CPER Project SOPHIE/STIC and Ondes. The work of [PERSON] and [PERSON] has been supported by the European Union's Horizon 2020 research and innovation programme under the [PERSON] grant agreement No 642355 FiWiN5G. [PERSON]-M. and G.C.D.B. acknowledge the Spanish Ministerio de Economia y Competitividad through Programa Estatal de Investigacion, Desarrollo e Inovacion Orientenda a los Retos de la Sociedad (grant iTWIT, TEC2016-76997-C3-3-R).  
**Acknowledgments:** The authors would like to thank [PERSON] (M2 ARS platform and Universite de Rennes 1), [PERSON] (Nano-Rennes platform and Universite de Rennes 1), and [PERSON] (Nano-Rennes platform and INSA de Rennes) for manufacturing the housing and for assistance in the assembly of the antenna. The authors are also grateful to [PERSON] (III-V Labs Thales-Alcatel) for lending the photodiode chip used in this work.  
**Conflicts of Interest:** The authors declare no conflict of interest.