Design and Performance of Microstrip Diplexers: A Review

The radiofrequency microstrip diplexers are widely demanded nowadays by modern wireless communication systems. Hence, several types of previously reported microstrip diplexers are reviewed and investigated in this work. Microstrip diplexers are three ports devices used for separating desired signals and delivering them through two (or more) different channels. The diplexers are investigated in three categories of dual-channel bandpass-bandpass diplexers, multichannel diplexers, and lowpassbandpass diplexers. The investigated multi-channel diplexers include a number of four-channel, six-channel, and eight-channel diplexers. Due to the hard design process, the number of reported diplexers with more than four channels is limited. The layout structures and theory design methods of the previously reported diplexers are studied. Moreover, their size and performance are compared while some explanations about their advantages and disadvantages are presented. This comparison includes insertion loss, return loss, fractional bandwidths, isolation, selectivity, and gaps between channels

Microstrip Diplexer Using Stepped Impedance Resonators

International audienceIn this paper, a compact diplexer based on coupled stepped impedance resonators (SIRs) is designed for Digital Communication System and the industrial, scientific and medical applications. The diplexer is composed from two band-pass filters operated at 1.8 and 2.45 GHz respectively. The size and the position of the SIR and the feed lines are determined through the theoretical design and the simulation. The diplexer has less than 2.2 dB insertion loss and more than 21 dB of isolation. The diplexer performances are investigated numerically by using Momentum ADS Agilent and CST microwave software.The electromagnetic simulated results of the proposed diplexer show a good agreement with the measured results