Closely spacified wide dual-band microstrip band pass filter using coupled stepped-impedace resonators

This paper presents the design and implementation of a wide dual-band band pass filter using a new method. The proposed filter is developed with two stepped-impedance resonators. Both the ends of the two resonators are mutually coupled. Transmission zeros then appears on both sides of two pass bands and in the rejection bands. The two bands of the developed filter in the paper are centered at 1.22 GHz and 2 GHz. with bandwidths .72 GHz and .7 GHz. The first band frequency is used inbuilt in Mobile for global positioning system (GPS) at 1227.60 MHz and global systems for mobile communications (GSM) at 900 MHz application is presented in this paper. The simulated return loss is greater than 25 dB and insertion loss is less than .12 dB over the WB with center frequency 1.22 GHz. Whereas return loss is greater than 21 dB and insertion loss is less than .2 dB over the WB with center frequency 2 GHz. In addition, the isolations between the two pass bands are greater than 20 dB over the wideband. The group delay from port1 to port2 is flat and less than .8 ns over both the pass bands.