Research Substrate Parameters On The Transmission Characteristics Of Microstrip Band-Pass Filter Effect

Microwave filter is the most important part of the radio technology, along with the rapid development of communication technology, microwave filter design technology with the needs of different applications, there have been many different filter circuit structures. Such as microstrip filters, coaxial filters, waveguide filters, surface acoustic wave (SAW) filters, ceramic filters and other media. Microstrip filters because of small size, low cost, light weight, high performance, easy to match with other integrated circuits and a series of advantages and with the current direction of the circuit design is used widely as a filter. It can be divided into parallel coupled microstrip filters, hairpin-type filter, mounting microstrip line filter, cross-coupled filter, parallel coupled line filters and other forms of split ring microstrip filter.With the developing of the computer and simulation software technology, the current microwave circuit design and simulation software are combined. In this article the ADS RF circuit simulation software is used to analyze the basic physical parameters, and simulate the basic structure of the circuit. And then to further optimize the circuit to match the required design technical parameters. Based ADS RF simulation software for circuit design can make the design process more concise, the circuit more accurate.The dielectric constant, loss, thickness and other parameters of microstrip filter substrate seriously influence the filter's transmission performance. Based on the basic theory and design methods of microstrip band pass filter, took parallel coupled microstrip band-pass filter as an example, this paper studied the influence of changing microstrip substrate parameters on microstrip band-pass filter's transmission performance, under different circumstances that dielectric substrate was epoxy resin, doped silicon and Rogers (RT/duroid) high-frequency substrates. The paper mainly researched different requirements on dielectric substrate parameters for filter design in microwave and millimeter wave band, and the performance of the designed filter at the same dielectric substrate and different frequency. For the same filter performance, circuit design was conducted by changing the thickness of dielectric substrate, and the corresponding filter frequency response was got. On the same PCB layout, by changing the loss tangent of dielectric substrate, the frequency response characteristics change of the filter circuit was analyzed, the influence of temperature on dielectric substrate's dielectric constant and doping concentration on filter circuit's frequency response characteristics was studied, in case of the phosphorus doped silicon—doped silicon substrate. The results have reference value for the design and production of modern microstrip band pass filter.