A Tutorial on Optical Feeding of Millimeter-Wave Phased Array Antennas for Communication Applications

Abstract

Given the interference avoidance capacity, high gain, and dynamical reconfigurability, phased array antennas (PAAs) have emerged as a key enabling technology for future broadband mobile applications. This is especially important at millimeter-wave (mm-wave) frequencies, where the high power consumption and significant path loss impose serious range constraints. However, at mm-wave frequencies the phase and amplitude control of the feeding currents of the PAA elements is not a trivial issue because electrical beamforming requires bulky devices and exhibits relatively narrow bandwidth. In order to overcome these limitations, different optical beamforming architectures have been presented. In this paper we review the basic principles of phased arrays and identify the main challenges, that is, integration of high-speed photodetectors with antenna elements and the efficient optical control of both amplitude and phase of the feeding current. After presenting the most important solutions found in the literature, we analyze the impact of the different noise sources on the PAA performance, giving some guidelines for the design of optically fed PAAs.

Structural optimization of optoelectronic components in millimeter-wave radio-transmitting modules

“…This makes optoelectronic control of PAA to be a solution for smart antennas in the millimeter and submillimeter ranges. However, the optoelectronic methods for PAA have serious problems associated with the integration of a high-speed photodetector with an antenna [9,10]. This requires careful design, in which particular attention should be paid to the analysis of energy balance.…”

“…Shown in Fig. 1 are some options for constructing modules to form radiation of a phased array, which are proposed for promising communication systems in MMR based on optoelectronic technologies [3,5,7,10].…”

“…Phase adjustment can be performed using the differential delay τ. For linear PAA, the condition of maximum gain [10]. The average output power of the RF signal can be defined as…”

Optical Beamforming Networks for Millimeter-Wave Wireless Communications

“…Conventionally, the beamforming and beamsteering of PAAs are implemented using electric beamforming networks that have analog and digital architectures. Analog architectures of electric beamforming generally utilize a phase shifter array that has a bulky size and narrow bandwidth, inducing a high cost and the beam squint problem [12,13]. Meanwhile, digital beamforming networks require that the numbers of high-speed digitalanalog converters (ADCs), analog-digital converters (DACs) and mixers are identical to those of antenna elements, which are too expensive to implement in PAAs with massive antenna elements [9,14].…”

“…Several application scenarios of OBFNs such as indoor coverage and mobile fronthaul have been proposed [29,[32][33][34][35][36][37][38]. Up to now, reviews about OBFNs have paid more attention on TTD architectures [8,12,15,20,21,39], but the roles and advancements of phase shifter architectures have not been discussed. Furthermore, relative advancements in materials, optical devices and electro-photonic integrations, which may improve the scalability of OBFNs, have not been discussed either.…”