As bandwidth is consumed at lower frequencies, the need for higher wireless data rates grows stronger, pushing wireless communications systems into the millimeter-wave (mmWave) frequency range. For wireless infrastructure systems such as base stations operating at mmWave frequencies in 5G wireless systems, antennas become a focal point in order to provide suitable gain, bandwidth, and field of view (FoV). On that front, a research team from The Eindhoven University of Technology (Eindhoven, The Netherlands) has combined technologies such as RF, in the form of a low-noise amplifier (LNA), and a photonic integrated circuit (PIC) to create a broadband mmWave antenna design with an optical beamformer to shrink the size of the feed system.
The hybrid antenna system shows potential for use in point-to-point backhaul systems, satellite communications (satcom) systems, and microwave and millimeter-wave 5G wireless infrastructure systems. The designers applied the focal-plane-array (FPA) concept to achieve high antenna gain and high effective isotropic radiated power (EIRP) with electronic beamsteering. By using a photonics beamformer, a broadband antenna for use from 20 to 40 GHz can be designed with a fiber-based interface to a central processing unit.
The novel antenna concept offers more than 40 dBi gain across a field of view of ±15 deg. at 28.5 GHz. The optical beamformer generates M beams simultaneously by using M laser diodes with separately tunable emission wavelengths. Optical phase shifters are used to achieve the phase shifts between the antenna elements. The hybrid antenna system is backed by several already-fabricated ICs, for several of the most critical functions in the system.
See “Building 5G Millimeter-Wave Wireless Infrastructure,” IEEE Antennas & Propagation Magazine, April 2019, pp. 53-62.