Nanjing University of Aeronautics and Astronautics (NUAA) is one of China’s premier learning and research institutions and has developed into a comprehensive university especially focused on aerospace engineering. Established in 1952, NUAA strives to provide a world-level research and education system for its 24,600 students, 600 of who are international students from over 30 countries.
THE DESIGN CHALLENGE
NUAA was searching for a more user-friendly, integrated alternative to the current set of high-frequency design tools used in the classroom. To objectively evaluate AWR’s Microwave Office® RF and microwave design software, the university chose to redesign an existing compact and high selectivity dual-band, dual-mode bandpass filter for GPS and WLAN applications. The filter was designed using a short, stub-loaded folded resonator with source load coupling. The 3dB fractional bandwidths of the two passbands were about 3.4 percent at 1.57GHz and 9.9 percent at 5.2GHz. Because there was interference between the main signal path and the folded arms of the resonator, it was necessary to generate five transmission zeros near the passband edges and in the upper stopband in order to improve the frequency selectivity and stopband performance.