Abstract
We present a novel photonic beamformer for a fully integrated transmit phased array antenna, together with an automatic procedure for tuning the delays in this system. Such an automatic tuning procedure is required because the large number of actuators makes manual tuning practically impossible. The antenna system is designed for the purpose of broadband aircraft-satellite communication in the Ku-band to provide satellite Internet connections on board the aircraft. The goal of the beamformer is to automatically steer the transmit antenna electronically in the direction of the satellite. This is done using a mix of phase shifters and tunable optical delay lines, which are all integrated on a chip and laid out in a tree structure. The Ku-band has a bandwidth of 0.5 GHz. We show how an optical delay line is automatically configured over this bandwidth, providing a delay of approximately 0.4 ns. The tuning algorithm calculates the best actuator voltages based on past measurements. This is the first time that such an automatic tuning scheme is used on a photonic beamformer for this type of transmit phased array antenna. We show that the proposed method is able to provide accurate beamforming (< 11.25{\deg} phase error over the whole bandwidth) for two different delay settings.
Highlights
B EAMFORMERS are used to steer the beam of a phased array antenna by controlling the phase added to the signal at each antenna element (AE) [1]
In order to get the same signal to each AE with a certain delay, a beamformer for a transmit phased array antenna consists of splitters and delay elements
In this work we describe the beamformer for the transmit phased array antenna from Fig. 2 together with its requirements, and we show how to tune this system with a different optimization algorithm
Summary
B EAMFORMERS are used to steer the beam of a phased array antenna by controlling the phase added to the signal at each antenna element (AE) [1]. In order to get the same signal to each AE with a certain delay, a beamformer for a transmit phased array antenna consists of splitters and delay elements These can be arranged in a tree structure to reduce the required number of delay elements [2]– [4]. In this work we describe the beamformer for the transmit phased array antenna from Fig. 2 together with its requirements, and we show how to tune this system with a different optimization algorithm. This online algorithm is not sensitive to model errors and can be used while the system is running
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