Compact Microstrip Triple-Mode Bandpass Filters Using Dual-Stub-Loaded Spiral Resonators

Abstract

Two new microstrip triple-mode resonators loaded with T-shaped open stubs using axially and centrally symmetric spiral structures, respectively, are presented. Spiraled for circuit size reduction, these two halfwavelength resonators can both generate three resonant modes over a wide frequency band by loading two T-stubs with different lengths. Due to the structural symmetry, they can be analyzed by odd-and even-mode method. To validate the design concept, two compact bandpass filters (BPFs) using these two novel resonators with center frequencies of 1.76 GHz and 2.44 GHz for the GSM1800 and WLAN/Zigbee applications, respectively, have been designed, fabricated and tested. The center frequencies and bandwidths can be tunable through the analysis of resonant frequency responses, fractional bandwidths and external quality factor versus the resonator parameters. The final measured results have achieved good consistence with the simulations of these two BPFs. where he is now a Professor. He has authored and co-authored over 80 papers in peer-reviewed journals and conference proceedings. He received the UESTC Outstanding Graduate Award in 2004, and the Excellent Doctoral Dissertation Award of Sichuan Province of China in 2012. His research interests include antenna array design, array signal processing, and microwave imaging methods.Jing AI was born in Sichuan, China. He received the B.respectively, where he is currently working toward the Ph.D. degree in Electromagnetic Field and Microwave Technology. His recent research interests include microwave and millimeter-wave circuits and systems.

Design of Reactance-to-Reactance Impedance Transformers Based on Conjugately Characteristic-Impedance Transmission Lines (CCITLs) and Meta-Smith Charts (MSCs)

“…For example, a reactance can be occurred from reactive components especially at the load. Most of studies about reactance matching transformers are in the form of tuning stubs, which are widely used for size reduction of microwave devices [2][3][4][5][6][7][8][9]. For example, in [2][3][4] open-circuited stubs are proposed to miniaturize filters and couplers.…”

“…For example, in [2][3][4] open-circuited stubs are proposed to miniaturize filters and couplers. Changing stub shapes (such as triangle and arc) is another way for size reduction [5][6][7][8]. In addition, stubs can also be shorten by using fractal structures [9].…”

Super High-Selectivity Fifth-Order Bandpass Filter with Twelve Transmission Zeros

“…High-selectivity bandpass filters (BPFs) with low insertion loss in the passband and high rejection in the stopband are drawing increasing attentions to meet the requirement of the modern wireless communication systems [1]. Recently, some works have been reported on introducing transmission zeros (TZs) to improve the out-of-band suppression of BPFs [2][3][4][5][6][7][8][9][10][11][12][13]. In [2][3][4], signal interference techniques have been invented for the generation of multiple TZs due to the construction of multiple transmission paths.…”