A microstrip bandpass filter using a symmetrical parallel coupled-line structure

This research proposes a new symmetrical bandpass filter structure based on micro strip parallel coupled-lines. Two bandpass filters have been computerized designed at the operating frequency about 1.9 GHz. Good agreement of experiment results and simulations have been obtained with low passband insertion loss (less than 1.5 dB) and high return loss (higher than 30 dB)at the center frequency. The proposed filters have small size, low insertion loss, high return loss and high rejection band, therefore they may be suitable for wireless communications.