Novel microstrip bandpass filter based on defected ground structure and slotline coupling techniques

✍ Scribed by Wenjie Feng; Kuan Deng; Wenquan Che; Shiwei Dong

• Publisher: John Wiley and Sons
• Year: 2010
• Tongue: English
• Weight: 132 KB
• Volume: 52
• Category: Article
• ISSN: 0895-2477
• DOI: 10.1002/mop.24816

✦ Synopsis

Abstract

A novel microstrip bandpass filter integrating the defected ground structure and slotline coupling technique is presented in this letter. A slotline resonator with a length of three‐quarter wavelength at central frequency is etched on the ground, while a pair of radial stubs is centrally introduced. Two microstrip open stubs are then placed above the slotline resonator, saying, on the top plane of the dielectric substrate. By properly adjusting the lengths of the microstrip stubs, a wideband passband filter is thus implemented using coupling between 50‐Ω microstrip (on the top plane) and the slotline (on the bottom). A prototype is fabricated to validate the proposed design strategies. The experiments and simulations both indicate good performances. The measured fractional bandwidth of prototype is about 89%, the return loss is less than –15 dB in the whole passband. In addition, the measured rejection bandwidth at –25 dB is even higher up to 10 GHz, thus, demonstrating a very good harmonic suppression ability. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 4–6, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24816