小型化高隔离度微带双工器的研究

【作者】 纪玉雪；

【导师】 吴文； 陈春红；

【作者基本信息】 南京理工大学 ， 机械电子工程， 2012， 硕士

【摘要】 微波双工器是用来完成现代无线多频多服务收发系统共用一个天线的一个至关重要的部件,其性能的优劣会直接影响到整个射频前端的工作性能。现代无线通信系统要求双工器具有重量轻、体积小、高阻带抑制和高隔离度的特性。阶梯阻抗谐振器(SIR)因具有结构简单与电学特性可调的特点,被广泛的应用在微波元件的设计中。本文通过对SIR特性的研究,提出了两种改进型的SIR结构,加载螺旋紧致谐振单元结构(SCMRC)的SCMRC-SIR与开槽阶梯阻抗谐振器SSIR。这两种改进型的SIR结构比传统的SIR结构具有更优良的性能。本文主要工作包括如下两个部分：利用慢波结构SCMRC替换传统SIR结构的低阻抗部分,提出了一种新型的SCMRC-SIR结构。相对于传统的SIR结构,本文提出的SCMRC-SIR结构具有更紧凑的电路尺寸,并且可在高于基波谐振频率处一个有限的传输零点。基于提出的SCMRC-SIR结构,设计了两个四阶切比雪夫响应带通滤波器。两个带通滤波器分别工作在GSM系统的上行频段和GPS系统工作频段,带宽都为8%。仿真结果显示这两个滤波器都有非常紧凑的电路尺寸、陡峭的过渡带与高抑制度的阻带等优点。基于这两个小型化高性能的带通滤波器,将他们通过T_型结连接起来,设计了一个微带双工器。该双工器具有很紧凑的电路尺寸0.12λg×0.21λ。测试结果表明该双工器在900MHz具有-50dB的隔离度,在1570MHz具有-55dB的隔离度。通过在传统的SIR谐振器的低阻抗部分刻蚀槽线,提出了一种结构紧凑的开槽阶梯阻抗谐振器结构(SSIR)。与SCMRC-SIR相比较,SSIR的尺寸进一步减小,并且具有更好的杂散频率抑制特性。基于提出的SSIR结构,设计了两个带宽都为10%、分别工作在GSM系统上行频段和GPS系统工作频段的四阶切比雪夫响应带通滤波器。仿真结果显示这两个带通滤波器都有非常紧凑的电路尺寸、陡峭的过渡带与高抑制度的阻带等优点。通过T-型结将这两个小型化高性能的带通滤波器连接起来,设计了一个微带双工器。与基于SCMRC-SIR结构的双工器相比较,该双工器具有更加紧凑的电路尺寸(0.11λg×0.14λg)和更高的隔离度(优于-60dB)。并且,与目前国内外文献报导相比较,在实现相当隔离度的情况下,该双双工器的尺寸最小。更多还原

【Abstract】 Microwave diplexer is an essential component to make the modern multi-band multi-service transceiver system have the ability to use a common antenna, and its property will affect the performance of overall RF system directly. The modern wireless system requires the diplexer have the characteristic of light weight, compact size, deep stopband rejection and high isolation. Due to its simple topology and tunable electrical property, the stepped impedance resonator (SIR) has been widely used in the design of microwave components. Through studying the characteristic of the conventional SIR, two improved SIRs are proposed in this paper, one using spiral compact microstrip resonant cell (SCMRC) instead of the low impedance section of SIR and the other with slotted line in the low impedance section of SIR. These two improved SIRs have much better performance than the conventional SIR. The main work of this paper includes two sections:By using the slow-wave structure SCMRC instead of the low impedance section of the conventional SIR, a novel structure called SCMRC-SIR is proposed. Compared to the conventional one, the SCMRC-SIR has a lower fundamental resonant frequency and has the ability to generate a finite transmission zero above its fundamental resonant frequency. Based on the proposed SCMRC-SIR, two fourth-order chebychev response bandpass filter are designed. Two filters operate at the GSM uplink band and GPS bands, and have a same fractional bandwidth of 8%. The simulated results show that two filters have compact size, sharp transition band and deep stopband rejection. By using a T-junction to connect these two compact and high performance bandpass filters, a microstrip diplexer is built. The fabricated diplexer has a compact size of 0.12λg×0.21λg. The measured results show that the fabricated filter has a high isolation of -50dB at 900MHz and -55dB at 1570MHz.By etching slotted lines in the low impedance section of the conventional SIR, a novel structure called SSIR is proposed. Compared to the abovementioned SCMRC-SIR, the SSIR has a compacter size and better spurious frequency rejection. Based on the proposed SSIR, two chebychev response bandpass filter with the same fractional bandwidth of 10% and operating at GSM uplink band and GPS band are designed. These two filters have the advantage of compact size, sharp transition band and deep stopband rejection. By using a T-junction to connect these two compact and high performance bandpass filters, a high performance diplexer is designed, simulated and fabricated. Compared to the diplexer utilizing SCMRC-SIR, the diplexer based on SSIR has a compacter size (0.11λg×0.14λg) and higher isolation (-61dB at 900MHz and-57dB at 1570MHz). Furthermore, as the author known, this diplexer has the smallest circuit area in the case of realizing about the same isolation compared to the reported ones.更多还原