A simplified and efficient approach for designing microstrip bandpass filters: Applications in satellite and 5G communications

Abstract

The C-band is extensively utilized in aviation radars and satellite communications (Satcom). Bandpass filters (BPFs) are crucial components in microwave systems operating within this frequency range. Therefore, it is important to develop a straightforward and effective method for designing BPFs with desired response characteristics. Currently, the prevailing approach for designing wideband microstrip BPFs involves employing multiple microstrip resonators and empirical techniques. However, some of these approaches lack comprehensiveness and a systematic design process. The design steps used for a specific type of microstrip filter with a particular cut-off frequency may not be directly applicable to developing a different filter with a distinct cut-off frequency. Conversely, having a systematic design process and software that can generate filter structures based on the filter order and response characteristics provides significant advantages in designing LC filters. Therefore, if we can design an LC filter with the desired response using conventional methods and subsequently convert it to a microstrip filter, we can achieve a more systematic design approach. The present paper proposes an innovative method to convert LC bandpass filters obtained using classical functions such as Elliptic, Butterworth, Chebyshev, and Bessel functions into microstrip BPFs. The designed microstrip BPFs offer a simple and repeatable design process and possess the flexibility to adjust the working frequency by employing a specific scaling factor. This adaptability makes the designed microstrip BPFs suitable for various applications, including Satcom and 5G systems.