Simulation of band pass filters based on multilayer technology

One of the integral parts of modern radio transmitting devices are bandpass filters that limit the out-of-band spectrum of electromagnetic radiation and the side effect of electromagnetic radiation, which is important in the framework of the dense distribution of the radio frequency band between radio services. Similar functions of bandpass filters are made as part of radio receivers and placed at the input. At the same time, they also perform the functions of a matching device between the radio receiving connection and the antenna-feeder path. Currently, there are known methods for the development of bandpass filters based on microstrip technology, which has such advantages as: a broad theoretical base, manufacturability, a wide selection of dielectric bases, and the possibility of simulation without using expensive software. At the same time, the disadvantage of microstrip technology is the need to expand the area of dielectric bases with an increase in the number of frequency-selective elements. Currently, a promising direction in the implementation of bandpass filters is their design based on a multilayer technology, which makes it possible to increase the number of frequency-selective elements without expanding the area of dielectric bases. Purpose of the study. The purpose of this article is to study the frequency-selective properties of design options for a bandpass filter based on multilayer technology, the basic element of which is a microstrip transition. Materials and methods. For the considered designs of the bandpass filter, a numerical electrodynamics simulation was carried out in the ANSYS HFSS software with an estimate of the dependence of the S-parameters in the frequency range of 0.2-4 GHz. The graphical distribution of the electromagnetic field in the microstrip transition was obtained. Results. From the results of the simulation it follows that the considered designs of the bandpass filter are characterized by good matching with a wave impedance of 50 Ohm (VSWR no more than 1.5 in a wide frequency range), low attenuation at the center frequency (no more than 0.5 dB), and by significant suppression of a signal outside its bandwidth (more than 30 dB). Conclusion. The simulation results prove the possibility of practical application of bandpass filters, developed on the basis of multilayer technology, as part of radio transmitting devices of radar and radio navigation systems.