Design of Modified Z-Shaped and T-Shaped Microstrip Filter Based on Transfer Function Analysis

作者：Karimi Gh^*; Siahkamari H; Hamedani F Khamin; Lalbakhsh A

来源：Wireless Personal Communications, 2015, 82(4): 2005-2016.

DOI：10.1007/s11277-015-2328-z

• Micriostrip lowpass filter
• Ultra wide stopband
• Transfer function
• Transmission zero

A new microstrip lowpass filter with compact size, ultra-wide stopband and sharp cutoff frequency is proposed. To achieve an ultra-wide stopband and sharp cutoff frequency, two Z-shaped resonators are added to the filter. To reduce the circuit size of the filter, cursive transmission line is also introduced. Moreover, exact equation for the most important transmission zeroes are obtained based on LC equivalent circuit and transfer function. A demonstration filter with 3 dB cut-off frequency at 1.89 has been designed, fabricated and measured. The results show a relative stopband bandwidth of 166.3%(referred to suppression degree of 25 dB), and a high figure of merit of 32,613.

• 出版日期2015-6