Wide stopband millimeter/terahertz lowpass filter using improved split ring resonator

Abstract

In this paper, an improved split-ring resonator (ISRR) cell is proposed to realize wide stopband and miniaturization. This cell comprises a transverse microstrip branch in middle and two gaps on both sides with tapped-line input and output. The transmission coefficient is derived for ISRR based on the distributed circuit theory and odd-even mode theory. Then the novel low-pass filter (LPF) is designed by cascading several ISRR cells in terahertz and millimeter. The ISRR LPF possesses great characteristics such as wide stopband, deep transmission zeros and small size. Finally, the proposed filter was processed and tested in millimeter. The measured results show that the proposed filter has low insertion loss from 0.5 to 0.7 dB in U-band and a stopband inhibition at 31.7 dB in 110 GHz.

Keywords:

• Millimeter and terahertz
• improved split-ring resonators
• low pass filter
• lumped parameter