This paper presents the design technique and simulation of Duplexer for GSM 900 band applications using microstrip technology.Two band pass filters with unequal impedance are designed. One filter with the 890-915MHz band and other filter with the 935-960MHz. Then these two filters are combined together in parallel to act as a duplexer with the uplink frequency band as 890-915MHz and downlink frequency band as 935-960MHz.The simulation is done using ADS software. Next, tuning and optimization are applied to achieve the low insertion loss.The proposed duplexer is a proof of concept for realizing duplexer functions using microstrip technology. In general, duplexers are built using high quality factor cavity filters. However, to prove the concept, duplexer is fabricated using FR-4 material which is readily available in India.

1. Runqi Zhang, Lei Zhu, “Synthesis and Design of Dual- Wideband Bandpass Filters with Internally Coupled Microstrip Lines”, IET Microwave Antennas Propagation, 2014, Vol.8, Iss.8, PP.556-563.
2. Shreyasi Srivatsava, R.K.Manjunath, P.Shanthi, “Design, Simulation and fabrication of a Microstrip Bandpass Filter”, International Journal of Science and Engineering Applications, Vol.3, Issue-5, 2014.
3. Chang Chen, Rongguo Zhou, “Design of Dual-Band Microwave Duplexers”, Electronic letters, Vol.50, No.3, pp.219-221, 30th January 2014.
4. Wei Qiang, Huang Ying, “Design Method of X Band Co-axial Duplexer”, IEEE Conference, Published Year: 2012, ISBN No. 978-1-4673-2185-3/12.
5. S. Srinath, “Design of 4th Order Parallel Coupled Microstrip Bandpass Filter at Dual Frequencies of 1.8GHz and 2.4 GHz for Wireless Application”, International Journal of Innovative Research in Computer and Communication Engineering, Vol.2 Issue-6, June 2014.
6. M.Latrach, H.Bennis, “Microstrip Triangular Loop resonator Duplexer”, International Journal of Computer and Communication Engineering, Vol.2, No.4, July 2013.
7. Ching-Wen Tang, Po-Hsien Wu, “Design of Wide Pass band/Stop band Microstrip Bandpass Filters with Stepped Coupled Lines”,IEEE Transactions on Microwave Theory and Techniques, Vol.61.No.3, March 2013.

@article{Suresha04051002,
title = " Design and Fabrication of Duplexer for GSM900 Band Applications ",
journal = "International Journal of Science and Engineering Applications (IJSEA)",
volume = "4",
number = "5",
pages = "245 - 249",
year = "2015",
author = " Suresha L, Sunil Kn,Umesh Kumar A,Shashi Kumar K,R K Manjunath,Dr.Nagamani K ",
}