Design of Wideband Microstrip Bandpass Filter for S-Band Application

This paper describes the design of wideband parallel coupled microstrip bandpass filter (BPF) for S-Band application. S-Band is the range of frequency from 2 GHz to 4 GHz which is a part of microwave system and a partly combination between Ultra High Frequency (UHF) and Super High Frequency (SHF) which including Wireless Local Area Network (WLAN), High-Speed Downlink Packet Access (HSDPA), Bluetooth, Worldwide Interoperability for Microwave Access (WiMAX) and Long Term Evolution (LTE) applications. In order to satisfy the needs for many applications to be used at once, S-Band microstrip bandpass filter is proposed as it functions to remove out other frequencies from the passband using planar microstrip transmission topologies. To design the prototype, certain constraints had to be identified, the lumped element works well in low frequencies but at high frequency problems arises which the inductor and capacitors are only available for a limited range of values and the distance between the filter components at microwave frequency is not negligible. Hence, the microstrip transmission line is used in the design as it capabilities handling wide band of fabricated. The BPF will be designed using a parallel coupled line method which will be simulated using Advanced Design System (ADS) software, fabricated using FR4 substrate and analyzed using a network analyzer. The design is compared between ideal case design (lumped element) and parallel coupled line method for insertion loss, S21 and return loss, S11 The results is acceptable between simulation and measures values which -4.89 dB and -14.591 dB for S21 and S11 respectively.