Examenspresentation av Sohaib Chaudhry

Supervisors: Viktor Chernikov and Artem Vilenskiy (Chalmers) and Sam Agneessens and Lars Manholm (Ericsson)
Examiner: Marianna Ivashina

Abstract
The advent of 5G and 6G technologies has significantly increased the performance demands in wireless communication. Higher frequencies are being utilized by Radio Access Networks (RAN) to enhance channel capacity, and wireless backhaul networks are exploring the possibility of operating at even higher frequencies to enable high-capacity networks. Recent trials have shown that W-band (92GHz-114GHz) can perform at the same level as E-band and is expected to provide more untapped spectrum for high-capacity wireless transport. However, high-gain antennas are required to enable long-distance, high-capacity, and robust W-band links, and their installation poses great challenges for tower stability requirements. Vinnova funded Project at Chalmers University of Technology focuses on a novel solution i.e., a high-gain electronically steerable antenna system operating in FDD (Frequency Division Duplex) configuration for backhaul links. The objective of this research is to enable FDD configuration in electronically steerable antennas through the design and integration of a compact W-band diplexer assembly.
The main objective of this master thesis is to design and optimize a compact W-band diplexer utilizing the K-Impedance Inverter and Coupling Matrix Method. The design features ten iris coupled resonator cavities assembled with a power divider in a T-junction topology, resulting in a 5th order Chebyshev type frequency response centered at 95.5GHz and 107.5GHz, respectively. Each diplexer channel has an effective bandwidth of 3GHz, with maximum passband return loss of -15dB and insertion loss of less than 1dB. To achieve the desired performance, the design underwent multiple optimization strategies, with the primary goal of reducing overall volume while maintaining low sensitivity to manufacturing tolerances i.e., ±15um. Various strategies were studied, including symmetrical and asymmetrical inductive and capacitive iris-based filters, dual-mode and higher-order-mode cavity resonators, H-plane junction, and evanescent mode filters. The strategy of using higher-order (TE102) mode filters was finalized, resulting in a compact diplexer assembly that was manufactured using precision CNC-milling and performance is validated through lab measurements. A competitive analysis between available designs in the literature and this research work was carried out to evaluate the advantages and drawbacks of the implemented design technique. Finally, the diplexer assembly was optimally integrated with the available Focal Plane Array, and a 3D Electromagnetic (EM) Model is generated.

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Sohaib and Marianna