Analysis and Design of an Interdigital Band-Pass Filter Developed with Distributed Elements Using Free Software

Developing band-pass filters in radio frequency circuits, especially with microstrip technology, is essential to compact the circuit design, reduce the signal spurious, and facilitate a transmission without or reduced noise. This paper presents the analysis and design of an interdigital band-pass filter developed with distributed elements (microstrip transmission lines) for applications in the UHF band. The development of the proposed filter includes design, simulation, implementation, and characterization for the radiofrequency IV band applications that belong to the frequency range between 470–584 MHz, according to the rules set up by the Ministry of Transport and Communications (MTC) of Peru. The band-pass filter passes many tests in a laboratory before obtaining an acceptable response between the simulation results with the open-source software QucsStudio and the implemented filter measurements. In the characterization and measurement process, the band-pass filter attenuates 5.23 dB in the central frequency settled in 515 MHz; In comparison, at the lower side-pass frequency of 492 MHz, it provides an attenuation of 5.89 dB, and at the higher frequency of 540 MHz, an attenuation of 8.69 dB has been achieved.