Public defence in Radio Science and Technology, M.Sc.(Tech.) Matti Kuosmanen

The title of the thesis: Studies on antenna arrays: advanced manufacturing methods and integration of microwave components

Thesis defender: Matti Kuosmanen
Opponent: Prof. Lars Jonsson, KTH Royal Institute of Technology, Sweden
Custos: Prof. Ville Viikari, Aalto University School of Electrical Engineering

Radars, electronic warfare devices, and telecommunication systems use antenna arrays to transmit and receive radio frequency (RF) signals. In comparison with a single antenna, antenna arrays can electrically modify their radiation pattern. Therefore, it is possible to strengthen signals from certain directions and attenuate them from other, non-desired directions. 

Along with the development of wireless systems using antenna arrays, also the requirements for antenna arrays have tightened. Larger bandwidth, smaller size, lower cost, and their suitability for various platforms are desired. This thesis provides solutions to these challenges by introducing novel manufacturing methods and presenting techniques for integrating microwave components into antenna arrays. 

One novel manufacturing method presented in this thesis is the use of hard plastic foam as a structural material of an antenna array. The actual antenna elements are metalized cavities that are milled inside a foam block. The antenna array made of foam is considerably lighter in weight than a conventionally manufactured array. The lower weight also makes the proposed antenna array suitable for various new platforms, such as unmanned aerial vehicles. The applicability and operation of the proposed array are investigated through computer simulations and the manufacturing of antenna prototypes. The integration of microwave components into an antenna array is studied from two aspects: the integration of wideband filters and amplifiers. The thesis presents a new method to integrate a band-pass or low-pass filter into antenna array elements. 

The integration of the filter does not increase the size of the antenna element, and the external front-end filter can be removed. This is beneficial especially with small RF systems that require a low weight and small size. Furthermore, the thesis investigates an active antenna array, where wideband, high-power amplifiers are integrated into antenna elements. This increases the integration level of the radio transmitter and potentially improves its bandwidth and efficiency.

Thesis available for public display 10 days prior to the defence at Aaltodoc.