Design of Microstrip Triplexer Using Common Dual-Mode Resonator with Multi-Spurious Mode Suppression for Multiband Applications

Abstract

A triplexer is an important component for channel separation in microwave front-end systems. This paper proposes a triplexers designed with common dual mode resonator sections have been proposed. By exploiting the variable frequency response of the stepped-impedance resonator, resonators can be shared by the three filter channels of the desired triplexer if their fundamental and the first spurious resonant frequency are properly assigned. Triplexer design method for suppressing spurious responses in the stopband by choosing the constitutive resonators with the same fundamental frequency, but staggered higher order resonant frequencies. The design concept is demonstrated by three of third order parallel-coupled bandpass filters. The bandpass filter is composed of three different stepped impedance resonators for which a general design guideline had been provided in order have the same fundamental frequency and different spurious frequencies. The measured results are in good agreement with the simulated predictions, whereby the spurious responses in the upper stopband can be suppressed below-25dB up to 14 GHz, which can be quite useful for multiband and multiservice applications in future wireless communication systems.

A Compact Microstrip Triplexer With a Novel Structure Using Patch and Spiral Cells for Wireless Communication Applications

“…The suppressed harmonics of the proposed triplexer are compared with the previous triplexers, and the results are demonstrated in Table 2. As presented in Table 2, some of the previous works' triplexers such as in [10,16] and [7] could attenuate the harmonics better than ours. However, they are large and have high insertion loss and low return loss in all channels, as compared with our proposed triplexer.…”

“…Recently, compact and high-performance microstrip triplexers are highly attractive for multichannel wireless and mobile systems. Accordingly, several types of microstrip triplexers have been reported in [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23]. Their designs are based on various types of microstrip resonators.…”

“…Using coupled hairpins, coupled U-shape and T-shape cells, a lowpass-bandpass triplexer with good isolation has been proposed in [13]. High impedance sections, and coupled open-loop resonator [14], parallel coupled lines integrated by a T-junction cell [15], and coupled hairpins [16] are the other utilised structures. The coupled hairpins and coupled open loops are commonly used in triplexer structures.…”

Novel low-loss microstrip triplexer using coupled lines and step impedance cells for 4G and WiMAX applications

“…Despite its large return loss and weak frequency selectivity, a significant reduction in the insertion losses could be seen. Although the low insertion loss at resonance frequency is an important issue, most of the reported triplexers could not reduce it [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18]. These triplexers have been designed using various microstrip structures.…”

“…It resonates at 1.8 GHz for digital communication systems, 3.2 GHz for * Correspondence: leila noori62@yahoo.com WiMAX, and 4.4 GHz for C-band applications. In [8], third-order parallel-coupled bandpass resonators were integrated to design a wide stopband triplexer. In [9], a star junction cell was connected to microstrip hairpin cells to realize wide fractional bandwidths.…”