JultikaUniversity of Oulu repository

Abstract

Modern communication systems look for higher operating frequencies to find more bandwidth to enable higher data rates. At a same time, these systems use larger and larger antenna arrays to compensate for the increased propagation losses by using antenna directivity. Often these systems use phased array approach for realizing steerable beam patterns. In phased arrays, the signal is usually divided in analogue domain to multiple transmit paths and combined in analogue domain from multiple receive paths. In this thesis, the aim is to generate a wideband modelling approach for analog signal routing in phased array transceivers that use radio frequency (RF) beamforming. In particular, the aim is to model the transfer functions of different signal paths from the sum node of all paths to the individual antennas and finally to the free space, to form a three-dimensional beam pattern that has frequency selective beam squint. The modelling approach and their behaviour in different symmetric and asymmetric beamforming architectures are presented and the performance of the system is observed through simulations by using beam patterns and equivalent amplitude responses in different directions. The impacts of array size, steering angle, and relative bandwidth are studied for the observed beam squint with different signal routing architectures to find their bandwidth limitations in different scenarios. The routing model also includes the impact of the dielectric materials of the circuit implementations.