High isolation microstrip bandpass diplexer for industry 4.0 communication

This paper presents a compact microstrip diplexer with high isolation for the new industry 4.0 communication. The proposed device consists of separating and combining signals having two widely different frequency bands. Moreover, the diplexer configuration is based on two bandpass filters, which are designed using interdigital lines. A T-shaped junction has been used to match between these filters and developed to miniature the diplexer. To validate the simulation results, we have fabricated the proposed diplexer. To justify the simulated and measured results, Monte Carlo simulation has been achieved. Experimental results show good performances, which are satisfactory return losses about of 11 dB, and the insertion losses are approximately 2.2 and 1.9 dB respectively of the two frequency bands [1.7-2.3] GHz and [3.2-4.2] GHz. The designed diplexer also exhibits high isolation, which is S-23 < - 60 dB between the two channels, and compact size is approximately 34 x 32 x 0.8 mm(3). These prove that proposed diplexer could be a good candidate for industry 4.0 communication.