Miniaturized Dual-Mode Resonators with Improved Double Square Loop and Inter-Digital Couple for WLAN Dual-Bands

A novel dual-mode double square loop resonator (DMDSLR) for dual-band band-pass filter (BPF) is presented in this paper. The simple meander loop in DMDSLR is studied to improve the performance of the conventional DMDSLR. Significant size reductions over 33% are achieved. In addition, the designed meander-loop DMDSLR filter shows lower insertion loss (2.24 and 2.28 dB), higher rejection level (28/56 dB and 53/36 dB), wider bandwidth (about 8.5% and 28%) at the 2.47 and 5.47 GHz bands, respectively. Two transmission zeros are placed between the two pass-bands and result in a good isolation.