Millimeter-wave antenna beam forming by radio-over-fiber with 1.3 μm light source and variable delay line

Efficiently Accommodating High-frequency-band Wireless Systems by Using Analog Radio-over-fiber

“…When a wireless signal arrives at a base station with multiple antenna elements, each element receives a wireless signal with a phase difference. While this phase difference is maintained, the wireless signals received There are two conventional remote-beamforming technologies: one assigns a separate optical fiber (a separate core in the case of multi-core fiber) to each antenna element [3] and the other [4,5] uses chromatic dispersion *5 to switch the beam direction by changing the wavelength assigned to each antenna element. By overcoming the problems of these conventional technologies (by fixing the wavelength assigned to each antenna element), our remote-beamforming technology has four advantages: (i) only one optical fiber (core) is used; (ii) optical-fiber-distance information is unnecessary; (iii) control of the optical filter at the base station is unnecessary; and (iv) the format of the wireless signal is unrestricted even if a high-frequency band and long-distance optical fiber are used.…”