6. Conclusion

In the chapter, we explored and demonstrated the effectiveness of using reconfigurable multiple-beam array feed network based on millimeter-wave integrated photonics beamformers for the phased array antennas, which were known for a long time in the radar technique, in the small cells of the incoming fifthgeneration mobile communication systems. The study was carried out using a specific example of designing an 88 optical Butler matrix-based photonics-steered beamforming network of a transmitting phased array antenna for a pico-cell remote station operating in the Ka/V-band with a 16% fractional bandwidth allocated as a promising one for future 5G systems. For this goal, we firstly reviewed the specialties of millimeter-wave photonics technique in 5G wireless networks of Radio-over-Fiber architecture. Then, to determine the input data for subsequent design, a theoretical background of array antenna beam steering using ideal models of phase shifters and true-time delay lines was presented. Comparison of the two most frequently used approaches to the design of multiple-beam antenna arrays based on Butler or Blass matrices showed the advantage of the first option for operation in the remote station of a 5G pico-cell.

A brief analysis of the available integrated millimeter-wave optical beamforming networks showed that the direction is at the initial stage of its development. A distinctive feature of the optical Butler matrix for designing beamformers is the

Design of Reconfigurable Multiple-Beam Array Feed Network Based on Millimeter-Wave… DOI: http://dx.doi.org/10.5772/intechopen.89076

simple possibility of reconfiguring the antenna system in two directions: frequency reconfiguration due to the rearrangement of the RF synthesizer and spatial reconfiguration due to the introduction of a multichannel optical switch at the input. As a result of the simulation experiments performed using VPIphotonics Design Suite and MATLAB software, for both the integrated optical Butler matrix itself and the beamformer based on it, an acceptable quality of beams formation in a particular 5G pico-cell was obtained.
