Compact Wideband Microstrip Bandpass Filter Using Quasi-Spiral Loaded Multiple-Mode Resonator

• Published in: IEEE microwave and wireless components letters Vol. 20; no. 11; pp. 607 - 609
• Main Authors: Nosrati, M, Mirzaee, M
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.11.2010; Institute of Electrical and Electronics Engineers
• Subjects: Applied sciences; Band pass filters; Bandpass filters; Bandwidth; Circuit properties; Electric, optical and optoelectronic circuits; Electronic circuits; Electronics; Estimates; Exact sciences and technology; Filtering theory; Frequency filters; Microstrip filters; Microwave circuits, microwave integrated circuits, microwave transmission lines, submillimeter wave circuits; Microwaves; Noise levels; Oscillators, resonators, synthetizers; Quasi-spiral loaded multi-mode resonator; Resonators; transmission zeroes; Tuning; Wideband; Wireless communication; Microstrip filters; Resonator; Wide band circuit; On line; Return loss; Compact design; Transmission zero; Ultra wide band; Quasi-spiral loaded multi-mode resonator; Transmission line; transmission zeroes; Insertion loss; On line processing; Band pass filter; Frequency response; Miniaturization; Passband
• ISSN: 1531-1309; 1558-1764
• DOI: 10.1109/LMWC.2010.2068570

In this letter, a new model for further reducing the size and increasing the bandwidth (BW) of a class of bandpass filter (BPF) utilizing multi-mode resonator is presented. A new technique based on spiral transmission line loading to achieve higher BW and further size reduction is analyzed for this class of BPF. A compact ultra wideband microstrip BPF is proposed by using this technique. The capability of tuning the transmission zeroes in the proposed model is also studied. Estimates for the frequencies of these transmission zeroes are directly presented. The overall BW of the proposed BPF is shown to be increased more than 12.6% and its size to be reduced more than 70% compared with the conventional ones. The proposed BPF provides a relatively wide 3 dB fractional bandwidth of 72.6% frequency response with two transmission zeros at the lower and upper stop-bands to provide a very sharp cutoff and low passband insertion-loss and good return-loss characteristics.