Design of absorptive filter integrated switch using lossy resonators at 2.4 GHz ISM band

• Main Author: Zobilah, Abdullah Mohammed Saghir
• Format: Thesis
• Language: English; English
• Published: 2021
• Subjects: T Technology (General); TK Electrical engineering. Electronics Nuclear engineering
• Online Access: http://eprints.utem.edu.my/id/eprint/26040/1/Design%20of%20absorptive%20filter%20integrated%20switch%20using%20lossy%20resonators%20at%202.4%20GHz%20ISM%20band.pdf; http://eprints.utem.edu.my/id/eprint/26040/2/Design%20of%20absorptive%20filter%20integrated%20switch%20using%20lossy%20resonators%20at%202.4%20GHz%20ISM%20band.pdf; http://eprints.utem.edu.my/id/eprint/26040/; https://plh.utem.edu.my/cgi-bin/koha/opac-detail.pl?biblionumber=121178
• Institution: Universiti Teknikal Malaysia Melaka

Radio frequency (RF) and microwave switches are important components in RF front end, as they control the signal circulation path. Up to now, many different types of RF and microwave switches have been designed. They usually have a very wide passband with no specific band selectivity. With the increasingly complex spectrum environment and the increased communication modes, the traditional design method has the drawback of large circuit size, high impedance matching loss, and high fabrication cost. Researchers have recently become interested in a microwave switch with integrated filtering response, which has the potential to solve these issues. Thus, several research works have been done to develop a filter integrated switch (FIS). Based on the literature, most of the previous studies introduced reflective FISs having a problem of extremely low reflection coefficient at the ports that are not switched to the antenna or called OFF-state ports. In this research work, a reconfigurable resonator-based absorptive filter integrated switch (FIS) was presented for the industrial, scientific, and medical (ISM) band. Three types of reconfigurable resonators were utilized (L-shape, ring, and T-shape resonator). The FIS was made up of two absorptive resonators, reconfiguring between band-stop and band-pass responses, and integrated with a single pole double throw (SPDT) switch. In particular, the FIS circuit was designed for the purpose of switching between the transmitter (Tx) mode and the receiver (Rx) mode, as well as to filter both the transmitted and received signals. A simple mathematical analysis of isolation and insertion loss of filter integrated SPDT switch was discussed. PIN diodes were used as the switching elements for the SPDT switch and to reconfigure between the band-stop and band-pass responses. The band-stop response was the ultimate reason for the isolation between the transmitter (Tx) and receiver (Rx). While the bandpass response was the ultimate reason for selecting the wanted signal. The proposed absorptive FIS design could be used for ISM band applications at an operation frequency of 2.45 GHz. As a result, the proposed FIS design exhibited 2 dB of insertion loss and better than 38 dB of isolation. The measurement results showed a good agreement with the simulation results. Therefore, the key advantages of the proposed FIS design include low insertion loss, high isolation and good reflection coefficient at both ON- and OFF-state ports. In addition, the proposed FIS has an absorptive feature with a smaller number of PIN diodes while maintaining a compact size.