Design and Fabrication of a Novel Compact Low-loss Microstrip Diplexer for WCDMA and WiMAX Applications

Abstract

In this paper, a novel miniaturized microstrip diplexer using two bandpass filters (BPFs) is designed and fabricated. The filters consist of stub loaded coupled lines. Additional stubs and Tshape feeding structures are added to miniaturize the size of the presented diplexer. With the adopted special structure, low insertion losses and compact size are obtained. The introduced diplexer operates at 2.12 GHz for WCDMA application and 3.94 GHz for WiMAX application. The obtained insertion losses are 0.25 dB at 2.12 GHz and 0.26 dB at 3.94 GHz. A design technique for analyzing the proposed resonator is introduced to tune the resonance frequencies and obtain a compact size. The size of the proposed diplexer is 23.4 × 16.9 mm 2 (0.038 λg 2). The measurement result of the fabricated diplexer validates the design technique and simulation results.

A Review on the Structure, Application and Performance of the Passive Microstrip Devices

“…M odern wireless communication systems widely need to microstrip passive devices such as filters, [1][2][3][4][5][6] diplexers, [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22] multiplexers (triplexers [23][24][25][26][27][28][29][30] and quadruplexers, [31][32][33][34][35][36][37] five-channel multiplexer [38] ), and couplers. [39][40][41][42][43][44][45][46][47][48][49] For all of these passive devices, it is very necessary to have small dimensions, low insertion loss (IL), low return loss (RL), suppressed undesired harmonics, sharp roll-off at the edge of passbands (high frequency selectivity), etc.…”

“…Several types of microstrip diplexers such as twochannel, multi-channel, bandpass-bandpass, and lowpassbandpass are presented in. [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22] They have three ports, called; port1, port2 and port3, which pass the desired signal through two different frequency channels. The channels are created among port1-port2 and port1-port3, so port1 is common.…”

Compact wide stopband microstrip diplexer with flat channels for WiMAX and wireless applications

“…However, it has a large size and losses. In [20], stub‐loaded coupled lines have been used to design a miniaturised microstrip diplexer with relatively large group delay. The proposed diplexers in [16, 18] have large insertion losses.…”

An Area-efficient Microstrip Diplexer with a Novel Structure and Low Group Delay for Microwave Wireless Applications

“…Microstrip diplexers are attractive devices for the frequency domain multiplexing in modern communication systems (Yahya, Rezaei and Nouri, 2020a). Several types of microstrip structures have been used to design diplexers for wireless applications Rezaei, Nouri and Mohammadi, 2019;Huang, et al, 2016;Rezaei, et al, 2019a;Jun-Mei, Zhou and Cao, 2016;Peng and Chiang, 2015;Rezaei, et al, 2019b;Salehi, et al, 2016;Rezaei and Noori, 2018;Chen, 2015;Xiao, 2015;Noori and Rezaei, 2017a;Mohamadi, 2017, Noori andRezaei, 2017b;Bui, et al, 2017;Guan, et al, 2014;Bukuru, Song and Xue, 2015;Yahya, Rezaei and Nouri, 2020b;. However, all of these diplexers occupy a large implementation area.…”

“…This diplexer could not suppress the harmonics whereas it has low frequency selectivity. In (Huang, et al, 2016), coupled stub loaded U-shape cells, in (Rezaei, et al, 2019a), coupled lines loaded by similar patch cells, in (Jun-Mei, Zhou and Cao, 2016), coupled U-shape structure, in (Peng and Chiang, 2015), meandrous close-loops connected to interdigital cells, in (Rezaei, et al, 2019b), coupled meandrous cells and in (Salehi, et al, 2016), and triangular open-loop resonators have been used to obtain dual-band band pass-band pass diplexers.…”