A simple procedure for designing a highly selective
microstrip bandpass filter of second order is presented in this
paper. The proposed filter is composed of two principal square
open-loop resonators and designed with planar structures on a Roger
substrate. It is intended for 5G applications, especially for
Sub-6 GHz range frequency [3.5–3.8 GHz]. The suggested band pass
filter has a very attractive compact size of
7 mm × 15.46 mm. The performance of this
simple miniaturized filter, which is characterized by high
selectivity in the band of interest, can be seen from its important
characteristics: Adaptation, Transmission and Coupling
Coefficients. The electromagnetic simulations and measurement
results are in good agreement, which validates the design idea and
procedure.