2026 Bhaskarareddy Microstrip Triplexer

The rapid proliferation of multi-standard fifth-generation (5G) New Radio sub-6 GHz systems have intensified the demand for compact, high-isolation multiplexing components capable of simultaneously routing multiple frequency channels through a single shared antenna port without cross-band interference. This paper presents the design and full-wave electromagnetic (EM) simulation of a compact microstrip triplexer operating at 2.2, 2.6, and 3.0 GHz for 5G sub-6 GHz applications. The proposed triplexer employs square open-loop resonators (SOLRs) arranged as three independent three-pole Chebyshev bandpass filter channels, yielding nine resonator poles in total. Each channel is synthesized from the standard normalized Chebyshev lowpass prototype with element values g₀ = g₄ = 1.0, g₁ = g₃ = 0.8516, and g₂ = 1.1032, with a fractional bandwidth of 3% per channel and 50 Ω system impedance. The three channels are integrated at a common input port via a T-junction, with connecting transmission line stubs dimensioned to enforce high inter-channel isolation. The triplexer is implemented on Rogers RT/Duroid 6010LM substrate with dielectric constant of 10.7, loss tangent of 0.0023, and thickness of 1.27 mm. Full-wave EM simulation results demonstrate return losses of 21.1 dB, 23.1 dB, and 22.8 dB; insertion losses of 1.08 dB, 1.01 dB, and 0.98 dB; and inter-channel isolations of 45.7 dB, 45.2 dB, and 45.7 dB for port pairs S₃₂, S₄₂, and S₄.