The Master’s thesis by researcher Abbas Hassan Ali—supervised by Prof. Dr. Faleh Mahdi Mousa—was defended at the Department of Electrical Engineering, College of Engineering, University of Basrah. The thesis is titled: Design of a Sharp Microwave Band Pass Filter for Selective 5G Mid-Band Communication

In this thesis, a sharp band-pass filter (BPF) with enhanced pass-band and
stop-band specifications is presented. The filter can be utilized for 5G mid-
band applications along with LTE 42 and LTE 43, which occupy the
frequency range (3.4-3.8 GHz), to comply with the standards of different
countries. The initial design of the filter consists of a high impedance
transmission line connecting the filter’s two ports, which are terminated by
50Ω resistors. Although this design results in reasonable pass-band
characteristics, its stop-band and transition-band characteristics are
relatively weak. Due to this shortcoming, the stop-band specifications and
the sharpness of the transition band of this design are enhanced by
locating sharp transmission zeros within the stop-band to determine the
filter bandwidth and to significantly increase the stop-band attenuation.
These modifications are achieved by inserting a pair of shunt short and
open circuit stubs, a pair of short-circuited U-shaped parasitic elements,
and a central short circuited U-shaped element. The filter is
mathematically analyzed and modelled, and the design steps are also
demonstrated. The agreement between the simulation and measurements
is very reasonable. The suggested filter results in a reduced insertion loss
within the entire pass-band with a value equal to 0.35 dB at the center
frequency of the filter. The stop-band attenuation approaches 20 dB for the
entire stop band, while the transition bandwidth is within 10% with respect
to the center frequency of the filter. The measured pass-band of the filter
covers the frequency range (3.3- 3.82 GHz), which is very close to the
frequency range of the 5G mid-band applications. The proposed filter is
compared with other high-performance designs, and it shows a very good
balance between size, complexity, and performance of the filter