Miniaturized Microstrip Diplexer Based on FR4 Substrate for Wireless Communications

Abstract

In this paper, the miniaturized microstrip diplexer has been designed for dual channels based on FR4 substrate material. It consists of two bandpass filters (BPFs) functioning under dissimilar frequency bands coupled with a unified junction. Every BPF has been created by a meandered line resonator, step impedance resonator, uniform impedance resonator, and input/output feed lines. The AWR electromagnetic simulator has been used for characterizing the frequency responses of the projected diplexer. Noble scattering parameter results with narrow band responses and negative group delay values are obtained for the proposed diplexer. The microstrip diplexer has an interesting band isolation between the two filters around 31 dB. The device has been successfully fabricated and verified with the simulations.

Design and analysis of a compact microstrip lowpass–bandpass diplexer with good performance for wireless applications

“…Some designers obtained negative group delays out of −3 dB passband frequencies [12, 13]. A negative group delay does not break causality [13]. However, at the first resonance frequency of the presented diplexer in [13] we can see a very high group delay of 46.1 ns.…”

“…However, both of them have high frequency ratios, while in [7] the bandpass channel is narrow. Some designers obtained negative group delays out of −3 dB passband frequencies [12, 13]. A negative group delay does not break causality [13].…”

A New Design Approach for a Compact Microstrip Diplexer with Good Passband Characteristics

“…In the comparison table, the data of these works: (Hussein, Mezaal and Alameri, 2021), (Yahya, Rezaei and Nouri, 2020), (Tahmasbi, Razaghian and Roshani, 2021), , (Shirkhar and Roshani, 2021), ), (Fernandez-Prieto, et al, 2018, and (Noori and Rezaei, 2017) are based on simulation results and the others are based on the measured results. As shown in Table I, our diplexer has low loss, compact size, good harmonic attenuation, and reasonable isolation.…”

“…Each channel is used for receiving or sending signals from an antenna (Majdi and Mezaal, 2022). Several types of microstrip diplexer are introduced in (Hussein, Mezaal and Alameri, 2021;Chen, et al, 2021;Yahya, Rezaei and Nouri, 2020;Lu, et al, 2020;Su, et al, 2020;Tahmasbi, Razaghian and Roshani, 2021;Shirkhar and Roshani, 2021;Zhanga, Zhu and Li, 2018;Rezaei, Yahya, Noori and Jamaluddin, 2019;Dembele, et al, 2019;Yousif and Ezzulddin, 2020;Fernandez-Prieto, et al, 2018;Guan, et al, 2019;Guan, et al, 2014;Noori and Rezaei, 2017). However, all of them occupy large area.…”

“…However, all of them occupy large area. Two bandpass filters (BPFs) consisting spiral cells and coupled lines are integrated for obtaining a microstrip diplexer in (Hussein, Mezaal and Alameri, 2021). It has some disadvantages such as undesired harmonics and high losses at both channels.…”