  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.
