Diplexers Based on Microstrip Line Resonators With Loaded Elements

Abstract

Abstract-In this paper, microstrip line resonators with loaded elements are proposed and studied to design microstrip diplexer. To demonstrate the design ideas, the equivalent circuits of the proposed resonators are built and studied. It is found that the different loads on different positions of the proposed half-wavelength resonator make the resonator have different features, which will easily control the characteristic of the diplexers. And here, resistor, open stub, and shorted stub are used as loaded elements. It is found the resistor loaded on the center of the microstrip line resonator can extremely reduce the unloaded quality factor of even-mode resonant frequency, which can be used to suppress the harmonics of the diplexer. The loaded open stub not only can reduce the size of the diplexer, but also can control the frequency ratio between the fundamental frequency and second harmonic of a resonator, which can increases the frequency ratio between the two passbands of the diplexer. As for the loaded shorted stub, it can enlarge the size of the diplexer. To demonstrate the design ideas, three diplexers are presented. The comparisons between the loaded and unloaded diplexers are given. The experimental results agree well to the theoretical predictions and simulations.

Synthesis of Microwave Resonator Diplexers Using Linear Frequency Transformation and Optimization

“…The nonzero coupling matrix element M pq are used as optimized variables and varying their values causes the response to change. The aim of the coupling matrix synthesis process is to select coupling matrix which produce a diplexer response by (9) coincide with the response obtained from (2). To this purpose, the cost function is proposed as…”

“…The most employed distribution network used today may be the T-junction (as in [1][2][3][4][5]) connecting the T X and RX filters. The diplexer with the T-junction configuration has drawbacks of large volume and time-consuming.…”

A novel microstrip diplexer design with tunable bandwidths and switchable channels for 4.5G applications

“…To date, many microstrip diplexers or triplexers have been studied by various researchers [7][8][9][10][11][12][13]. These works have focused on obtaining multiple channels, low insertion losses at all channels, and high isolation between the output ports [8][9][10][11][12][13].…”

Design of Compact Quadruplexer Based on Defected Stepped Impedance Resonators

“…In [4], the authors presented a triplexer with high isolation at the cost of increasing circuit size due to the additional matching network based on the stepped-impedance resonators. In [5], novel microstrip line resonators were proposed to design a microstrip diplexer. Those novel resonators can be used to control the characteristic of the diplexers but with the penalty of additional loaded elements.…”

“…In these communication systems, the multiplexers are an essential component for channel separation in microwave front-end systems. Recently, much research has been focused on developing various kinds of multiplexers [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19].…”